diff --git a/README.md b/README.md
index fb94008d8..84f931595 100644
--- a/README.md
+++ b/README.md
@@ -96,6 +96,59 @@ exit status 1
 ```
 Please refer to the [secret pkg](./pkg/secret/secret.go)'s use of the validate method for more information.
 
+### BMC Package
+The BMC package can be used to access the BMC's Redfish API, run BMC's CLI commands or getting the systems' serial console. Credentials for both Redfish and SSH user, the SSH port and timeouts need to be passed as parameters of the New() method. E.g.
+
+```
+redfishUser := bmc.User{Name: "redfishuser1", Password: "redfishpass1"}
+sshUser := bmc.User{Name: "sshuser1", Password: "sshpass1"}
+timeOuts := bmc.TimeOuts{Redfish: 10*time.Second, SSH: 10*time.Second}
+
+bmc, err := bmc.New("1.2.3.4", redfishUser, sshUser, 22, timeOuts)
+```
+
+You can check an example program for the BMC package [here](usage/bmc/bmc.go).
+
+#### BMC's Redfish API
+The access to BMC's Redfish API is done by methods that encapsulate the underlaying HTTP calls made by the external gofish library. The redfish system index is defaulted to 0, but it can be changed with `SetSystemIndex()`:
+```
+const systemIndex = 3
+err = bmc.SetSystemIndex(systemIndex)
+if err != nil {
+    ...
+}
+
+manufacturer, err := bmc.SystemManufacturer()
+if err != nil {
+    ...
+}
+
+fmt.Printf("System %d's manufacturer: %v", systemIndex, manufacturer)
+
+```
+
+#### BMC's CLI
+The method `RunCLICommand` has been implemented to run CLI commands.
+```
+func (bmc *BMC) RunCLICommand(cmd string, combineOutput bool, timeout time.Duration) stdout string, stderr string, err error)
+```
+This method is not interactive: it blocks the caller until the command ends, copying its output into stdout and stderr strings.
+
+#### Serial Console
+The method `OpenSerialConsole` can be used to get the systems's serial console, which is tunneled in the an underlaying SSH session.
+```
+func (bmc *BMC) OpenSerialConsole(openConsoleCliCmd string) (io.Reader, io.WriteCloser, error)
+```
+The user gets a (piped) reader and writer interfaces in order to read the output or write custom input (like CLI commands) in a interactive fashion.
+A use case for this is a test case that needs to wait for some pattern to appear in the system's serial console after rebooting the system.
+
+The `openConsoleCliCmd` is the command that will be sent to the BMC's (SSH'd) CLI to open the serial console. In case the user doesn't know the command,
+it can be left empty. In that case, there's a best effort mechanism that will try to guess the CLI command based on the system's manufacturer, which will
+be internally retrieved using the Redfish API.
+
+It's important to close the serial console using the method `bmc.CloseSerialConsole()`, which closes the underlying SSH session. Otherwise, BMC's can reach
+the maximum number of concurrent SSH sessions making other (SSH'd CLI) commands to fail. See an example program [here](usage/bmc/bmc.go).
+
 # eco-goinfra - How to contribute
 
 The project uses a development method - forking workflow
diff --git a/go.mod b/go.mod
index 878d9a23a..11878ffac 100644
--- a/go.mod
+++ b/go.mod
@@ -54,6 +54,7 @@ require (
 	github.com/stmcginnis/gofish v0.15.0
 	github.com/stretchr/testify v1.9.0
 	github.com/vmware-tanzu/velero v1.12.1
+	golang.org/x/crypto v0.23.0
 	open-cluster-management.io/api v0.12.0
 )
 
@@ -192,7 +193,6 @@ require (
 	go.mongodb.org/mongo-driver v1.11.1 // indirect
 	go.starlark.net v0.0.0-20230525235612-a134d8f9ddca // indirect
 	go4.org v0.0.0-20200104003542-c7e774b10ea0 // indirect
-	golang.org/x/crypto v0.23.0 // indirect
 	golang.org/x/mod v0.15.0 // indirect
 	golang.org/x/oauth2 v0.15.0 // indirect
 	golang.org/x/sync v0.7.0 // indirect
diff --git a/pkg/bmc/bmc.go b/pkg/bmc/bmc.go
index 2069ae80e..6828bb037 100644
--- a/pkg/bmc/bmc.go
+++ b/pkg/bmc/bmc.go
@@ -1,18 +1,24 @@
 package bmc
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"time"
 
 	"github.com/golang/glog"
 	"github.com/stmcginnis/gofish"
 	"github.com/stmcginnis/gofish/redfish"
+	"golang.org/x/crypto/ssh"
 )
 
 const (
 	defaultTimeOut = 5 * time.Second
+
+	manufacturerDell = "Dell Inc."
+	manufacturerHPE  = "HPE"
 )
 
 var (
@@ -21,6 +27,12 @@ var (
 		Redfish: defaultTimeOut,
 		SSH:     defaultTimeOut,
 	}
+
+	// CLI command to get the serial console (virtual serial port).
+	cliCmdSerialConsole = map[string]string{
+		manufacturerHPE:  "VSP",
+		manufacturerDell: "console com2",
+	}
 )
 
 // User holds the Name and Password for a user (ssh/redfish).
@@ -44,14 +56,17 @@ type BMC struct {
 	host        string
 	redfishUser User
 	sshUser     User
+	sshPort     uint16
 	systemIndex int
 
 	timeOuts TimeOuts
+
+	sshSessionForSerialConsole *ssh.Session
 }
 
 // New returns a new BMC struct. The default system index to be used in redfish requests is 0.
 // Use SetSystemIndex to modify it.
-func New(host string, redfishUser, sshUser User, timeOuts TimeOuts) (*BMC, error) {
+func New(host string, redfishUser, sshUser User, sshPort uint16, timeOuts TimeOuts) (*BMC, error) {
 	glog.V(100).Infof("Initializing new BMC structure with the following params: %s, %v, %v, %v (system index = 0)",
 		host, redfishUser, sshUser, timeOuts)
 
@@ -72,6 +87,10 @@ func New(host string, redfishUser, sshUser User, timeOuts TimeOuts) (*BMC, error
 		errMsgs = append(errMsgs, "ssh user's name is empty")
 	}
 
+	if sshPort == 0 {
+		errMsgs = append(errMsgs, "ssh port is zero")
+	}
+
 	if sshUser.Password == "" {
 		errMsgs = append(errMsgs, "ssh user's password is empty")
 	}
@@ -105,6 +124,7 @@ func New(host string, redfishUser, sshUser User, timeOuts TimeOuts) (*BMC, error
 		host:        host,
 		redfishUser: redfishUser,
 		sshUser:     sshUser,
+		sshPort:     sshPort,
 		timeOuts:    timeOuts,
 		systemIndex: 0,
 	}, nil
@@ -347,3 +367,202 @@ func redfishGetSystemSecureBoot(redfishClient *gofish.APIClient, systemIndex int
 
 	return sboot, nil
 }
+
+// CreateCLISSHSession creates a ssh Session to the host.
+func (bmc *BMC) CreateCLISSHSession() (*ssh.Session, error) {
+	glog.V(100).Infof("Creating SSH session to run commands in the BMC's CLI.")
+
+	config := &ssh.ClientConfig{
+		User: bmc.sshUser.Name,
+		Auth: []ssh.AuthMethod{
+			ssh.Password(bmc.sshUser.Password),
+			ssh.KeyboardInteractive(func(user, instruction string, questions []string,
+				echos []bool) (answers []string, err error) {
+				answers = make([]string, len(questions))
+				// The second parameter is unused
+				for n := range questions {
+					answers[n] = bmc.sshUser.Password
+				}
+
+				return answers, nil
+			}),
+		},
+		Timeout:         bmc.timeOuts.SSH,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+
+	// Establish SSH connection
+	client, err := ssh.Dial("tcp", fmt.Sprintf("%s:%d", bmc.host, bmc.sshPort), config)
+	if err != nil {
+		glog.V(100).Infof("Failed to connect to BMC's SSH server: %v", err)
+
+		return nil, fmt.Errorf("failed to connect to BMC's SSH server: %w", err)
+	}
+
+	// Create a session
+	session, err := client.NewSession()
+	if err != nil {
+		glog.V(100).Infof("Failed to create a new SSH session: %v", err)
+
+		return nil, fmt.Errorf("failed to create a new ssh session: %w", err)
+	}
+
+	return session, nil
+}
+
+// RunCLICommand runs a CLI command in the BMC's console. This method will block until the command
+// has finished, and its output is copied to stdout and/or stderr if applicable. If combineOutput is true,
+// stderr content is merged in stdout. The timeout param is used to avoid the caller to be stuck forever
+// in case something goes wrong or the command is stuck.
+func (bmc *BMC) RunCLICommand(cmd string, combineOutput bool, timeout time.Duration) (
+	stdout string, stderr string, err error) {
+	glog.V(100).Infof("Running CLI command in BMC's CLI: %s", cmd)
+
+	sshSession, err := bmc.CreateCLISSHSession()
+	if err != nil {
+		glog.V(100).Infof("Failed to connect to CLI: %v", err)
+
+		return "", "", fmt.Errorf("failed to connect to CLI: %w", err)
+	}
+
+	defer sshSession.Close()
+
+	var stdoutBuffer, stderrBuffer bytes.Buffer
+	if !combineOutput {
+		sshSession.Stdout = &stdoutBuffer
+		sshSession.Stderr = &stderrBuffer
+	}
+
+	var combinedOutput []byte
+
+	errCh := make(chan error)
+	go func() {
+		var err error
+		if combineOutput {
+			combinedOutput, err = sshSession.CombinedOutput(cmd)
+		} else {
+			err = sshSession.Run(cmd)
+		}
+		errCh <- err
+	}()
+
+	timeoutCh := time.After(timeout)
+
+	select {
+	case <-timeoutCh:
+		glog.V(100).Info("CLI command timeout")
+
+		return stdoutBuffer.String(), stderrBuffer.String(), fmt.Errorf("timeout running command")
+	case err := <-errCh:
+		glog.V(100).Info("Command run error: %v", err)
+
+		if err != nil {
+			return stdoutBuffer.String(), stderrBuffer.String(), fmt.Errorf("command run error: %w", err)
+		}
+	}
+
+	if combineOutput {
+		return string(combinedOutput), "", nil
+	}
+
+	return stdoutBuffer.String(), stderrBuffer.String(), nil
+}
+
+// OpenSerialConsole opens the serial console port. The console is tunneled in an underlying (CLI)
+// ssh session that is opened in the BMC's ssh server. If openConsoleCliCmd is
+// provided, it will be sent to the BMC's cli. Otherwise, a best effort will
+// be made to run the appropriate cli command based on the system manufacturer.
+func (bmc *BMC) OpenSerialConsole(openConsoleCliCmd string) (io.Reader, io.WriteCloser, error) {
+	glog.V(100).Infof("Opening serial console on %v.", bmc.host)
+
+	if bmc.sshSessionForSerialConsole != nil {
+		glog.V(100).Infof("There is already a serial console opened for %v's BMC. Use OpenSerialConsole() first.",
+			bmc.host)
+
+		return nil, nil, fmt.Errorf("there is already a serial console opened for %v's BMC", bmc.host)
+	}
+
+	cliCmd := openConsoleCliCmd
+	if cliCmd == "" {
+		// no cli command to get console port was provided, try to guess based on
+		// manufacturer.
+		manufacturer, err := bmc.SystemManufacturer()
+		if err != nil {
+			glog.V(100).Infof("Failed to get redifsh system manufacturer for %v: %v", bmc.host, err)
+
+			return nil, nil, fmt.Errorf("failed to get redfish system manufacturer for %v: %w", bmc.host, err)
+		}
+
+		var found bool
+		if cliCmd, found = cliCmdSerialConsole[manufacturer]; !found {
+			glog.V(100).Infof("CLI command to get serial console not found for manufacturer for %v: %v",
+				bmc.host, manufacturer)
+
+			return nil, nil, fmt.Errorf("cli command to get serial console not found for manufacturer for %v: %v",
+				bmc.host, manufacturer)
+		}
+	}
+
+	sshSession, err := bmc.CreateCLISSHSession()
+	if err != nil {
+		glog.V(100).Infof("Failed to create underlying ssh session for %v: %v", bmc.host, err)
+
+		return nil, nil, fmt.Errorf("failed to create underlying ssh session for %v: %w", bmc.host, err)
+	}
+
+	// Pipes need to be retrieved before session.Start()
+	reader, err := sshSession.StdoutPipe()
+	if err != nil {
+		glog.V(100).Infof("Failed to get stdout pipe from %v's ssh session: %v", bmc.host, err)
+
+		_ = sshSession.Close()
+
+		return nil, nil, fmt.Errorf("failed to get stdout pipe from %v's ssh session: %w", bmc.host, err)
+	}
+
+	writer, err := sshSession.StdinPipe()
+	if err != nil {
+		glog.V(100).Infof("Failed to get stdin pipe from from %v's ssh session: %w", bmc.host, err)
+
+		_ = sshSession.Close()
+
+		return nil, nil, fmt.Errorf("failed to get stdin pipe from %v's ssh session: %w", bmc.host, err)
+	}
+
+	err = sshSession.Start(cliCmd)
+	if err != nil {
+		glog.V(100).Infof("Failed to start CLI command %q on %v: %v", cliCmd, bmc.host, err)
+
+		_ = sshSession.Close()
+
+		return nil, nil, fmt.Errorf("failed to start serial console with cli command %q on %v: %w", cliCmd, bmc.host, err)
+	}
+
+	go func() { _ = sshSession.Wait() }()
+
+	bmc.sshSessionForSerialConsole = sshSession
+
+	return reader, writer, nil
+}
+
+// CloseSerialConsole closes the serial console's underlying ssh session.
+func (bmc *BMC) CloseSerialConsole() error {
+	glog.V(100).Infof("Closing serial console for %v.", bmc.host)
+
+	if bmc.sshSessionForSerialConsole == nil {
+		glog.V(100).Infof("No underlying ssh session found for %v. Please use OpenSerialConsole() first.", bmc.host)
+
+		return fmt.Errorf("no underlying ssh session found for %v", bmc.host)
+	}
+
+	err := bmc.sshSessionForSerialConsole.Close()
+	if err != nil {
+		glog.V(100).Infof("Failed to close underlying ssh session for %v: %v", bmc.host, err)
+
+		return fmt.Errorf("failed to close underlying ssh session for %v: %w", bmc.host, err)
+	}
+
+	bmc.sshSessionForSerialConsole = nil
+
+	return nil
+}
diff --git a/pkg/bmc/bmc_test.go b/pkg/bmc/bmc_test.go
index 50c852f98..31ec26ef4 100644
--- a/pkg/bmc/bmc_test.go
+++ b/pkg/bmc/bmc_test.go
@@ -131,6 +131,10 @@ func createFakeRedfishLocalServer(secureBootEnabled bool, callbacks redfishAPIRe
 	return redfishServer
 }
 
+const (
+	defaultSSHPort = 22
+)
+
 var (
 	validUser     = User{"user1", "pass1"}
 	validTimeOuts = TimeOuts{Redfish: 1 * time.Minute, SSH: 15 * time.Second}
@@ -148,6 +152,7 @@ func TestBMC_New(t *testing.T) {
 		host           string
 		redfishUser    User
 		sshUser        User
+		sshPort        uint16
 		tiemeouts      TimeOuts
 		expectedErrMsg string
 	}{
@@ -156,6 +161,7 @@ func TestBMC_New(t *testing.T) {
 			host:        "",
 			redfishUser: User{},
 			sshUser:     User{},
+			sshPort:     defaultSSHPort,
 			tiemeouts:   TimeOuts{},
 			expectedErrMsg: "host is empty, redfish user's name is empty, redfish user's password is empty, " +
 				"ssh user's name is empty, ssh user's password is empty, redfish timeout is 0, ssh timeout is 0",
@@ -165,6 +171,7 @@ func TestBMC_New(t *testing.T) {
 			host:           "1.2.3.4",
 			redfishUser:    validUser,
 			sshUser:        validUser,
+			sshPort:        defaultSSHPort,
 			tiemeouts:      validTimeOuts,
 			expectedErrMsg: "",
 		},
@@ -173,6 +180,7 @@ func TestBMC_New(t *testing.T) {
 			host:           "",
 			redfishUser:    validUser,
 			sshUser:        validUser,
+			sshPort:        defaultSSHPort,
 			tiemeouts:      validTimeOuts,
 			expectedErrMsg: "host is empty",
 		},
@@ -181,6 +189,7 @@ func TestBMC_New(t *testing.T) {
 			host:           "1.2.3.4",
 			redfishUser:    User{Password: "pass1"},
 			sshUser:        validUser,
+			sshPort:        defaultSSHPort,
 			tiemeouts:      validTimeOuts,
 			expectedErrMsg: "redfish user's name is empty",
 		},
@@ -189,6 +198,7 @@ func TestBMC_New(t *testing.T) {
 			host:           "1.2.3.4",
 			redfishUser:    User{Name: "user2"},
 			sshUser:        validUser,
+			sshPort:        defaultSSHPort,
 			tiemeouts:      validTimeOuts,
 			expectedErrMsg: "redfish user's password is empty",
 		},
@@ -197,6 +207,7 @@ func TestBMC_New(t *testing.T) {
 			host:           "1.2.3.4",
 			redfishUser:    validUser,
 			sshUser:        User{Password: "pass1"},
+			sshPort:        defaultSSHPort,
 			tiemeouts:      validTimeOuts,
 			expectedErrMsg: "ssh user's name is empty",
 		},
@@ -205,14 +216,25 @@ func TestBMC_New(t *testing.T) {
 			host:           "1.2.3.4",
 			redfishUser:    validUser,
 			sshUser:        User{Name: "user2"},
+			sshPort:        defaultSSHPort,
 			tiemeouts:      validTimeOuts,
 			expectedErrMsg: "ssh user's password is empty",
 		},
+		{
+			name:           "ssh port is zero",
+			host:           "1.2.3.4",
+			redfishUser:    validUser,
+			sshUser:        validUser,
+			sshPort:        0,
+			tiemeouts:      validTimeOuts,
+			expectedErrMsg: "ssh port is zero",
+		},
 		{
 			name:           "invalid redfish timeout",
 			host:           "1.2.3.4",
 			redfishUser:    validUser,
 			sshUser:        validUser,
+			sshPort:        defaultSSHPort,
 			tiemeouts:      TimeOuts{Redfish: 0, SSH: 1 * time.Second},
 			expectedErrMsg: "redfish timeout is 0",
 		},
@@ -221,6 +243,7 @@ func TestBMC_New(t *testing.T) {
 			host:           "1.2.3.4",
 			redfishUser:    validUser,
 			sshUser:        validUser,
+			sshPort:        defaultSSHPort,
 			tiemeouts:      TimeOuts{Redfish: 1 * time.Second, SSH: 0},
 			expectedErrMsg: "ssh timeout is 0",
 		},
@@ -228,7 +251,7 @@ func TestBMC_New(t *testing.T) {
 
 	for _, testCase := range testCases {
 		t.Run(testCase.name, func(newT *testing.T) {
-			_, err := New(testCase.host, testCase.redfishUser, testCase.sshUser, testCase.tiemeouts)
+			_, err := New(testCase.host, testCase.redfishUser, testCase.sshUser, testCase.sshPort, testCase.tiemeouts)
 			if err != nil {
 				if err.Error() != testCase.expectedErrMsg {
 					newT.Errorf("Unexpected error. Got: %v, Want: %s", err, testCase.expectedErrMsg)
@@ -265,7 +288,7 @@ func TestBMC_SetSystemIndex(t *testing.T) {
 		},
 	}
 
-	bmc, err := New("1.2.3.4", validUser, validUser, DefaultTimeOuts)
+	bmc, err := New("1.2.3.4", validUser, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
@@ -297,7 +320,7 @@ func TestBMC_Manufacturer(t *testing.T) {
 	redfishAuth := User{"user1", "pass1"}
 
 	// No ssh credentials needed.
-	bmc, err := New(host, redfishAuth, validUser, DefaultTimeOuts)
+	bmc, err := New(host, redfishAuth, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -346,7 +369,8 @@ func TestBMC_ManufacturerTimeout(t *testing.T) {
 	redfishAuth := User{"user1", "pass1"}
 
 	// Set a maximum 100ms timeout from redfish api.
-	bmc, err := New(host, redfishAuth, validUser, TimeOuts{Redfish: 100 * time.Millisecond, SSH: 100 * time.Millisecond})
+	bmc, err := New(host, redfishAuth, validUser, defaultSSHPort,
+		TimeOuts{Redfish: 100 * time.Millisecond, SSH: 100 * time.Millisecond})
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -378,7 +402,7 @@ func Test_BMCSecureBootStatus(t *testing.T) {
 	redfishAuth := User{"user1", "pass1"}
 
 	// No ssh credentials needed.
-	bmc, err := New(host, redfishAuth, validUser, DefaultTimeOuts)
+	bmc, err := New(host, redfishAuth, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -418,7 +442,7 @@ func Test_BMCSecureBootStatus(t *testing.T) {
 	redfishAuth = User{"user1", "pass1"}
 
 	// No ssh credentials needed.
-	bmc, err = New(host, redfishAuth, validUser, DefaultTimeOuts)
+	bmc, err = New(host, redfishAuth, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -445,7 +469,7 @@ func Test_BMCSecureBootEnable(t *testing.T) {
 	redfishAuth := User{"user1", "pass1"}
 
 	// No ssh credentials needed.
-	bmc, err := New(host, redfishAuth, validUser, DefaultTimeOuts)
+	bmc, err := New(host, redfishAuth, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -485,7 +509,7 @@ func Test_BMCSecureBootDisable(t *testing.T) {
 	redfishAuth := User{"user1", "pass1"}
 
 	// No ssh credentials needed.
-	bmc, err := New(host, redfishAuth, validUser, DefaultTimeOuts)
+	bmc, err := New(host, redfishAuth, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -526,7 +550,7 @@ func Test_BMCSystemForceReboot(t *testing.T) {
 	redfishAuth := User{"user1", "pass1"}
 
 	// No ssh credentials needed.
-	bmc, err := New(host, redfishAuth, validUser, DefaultTimeOuts)
+	bmc, err := New(host, redfishAuth, validUser, defaultSSHPort, DefaultTimeOuts)
 	if err != nil {
 		t.Errorf("Failed to instantiate bmc: %v", err)
 	}
@@ -550,3 +574,80 @@ func Test_BMCSystemForceReboot(t *testing.T) {
 		t.Errorf("Unexpected error when getting manufacturer of non-existent system. Want: %v, Got: %v", expectedErrMsg, err)
 	}
 }
+
+func Test_BMCCreateCLISSHSession(t *testing.T) {
+	timeouts := TimeOuts{Redfish: 1 * time.Second, SSH: 10 * time.Millisecond}
+
+	bmc, err := New("1.2.3.4", validUser, validUser, defaultSSHPort, timeouts)
+	if err != nil {
+		t.Errorf("Failed to instantiate bmc: %v", err)
+	}
+
+	const expectedErrMsg = `failed to connect to BMC's SSH server: dial tcp 1.2.3.4:22: i/o timeout`
+
+	_, err = bmc.CreateCLISSHSession()
+	if err == nil {
+		t.Error("Err should not be nil.")
+	} else if err.Error() != expectedErrMsg {
+		t.Errorf("Unexpected error. Expected %v, Got: %v", expectedErrMsg, err.Error())
+	}
+}
+
+func Test_BMCRunCLICommand(t *testing.T) {
+	// Force SSH timeout to 10ms to make it fail faster.
+	timeouts := TimeOuts{Redfish: 1 * time.Second, SSH: 10 * time.Millisecond}
+
+	bmc, err := New("1.2.3.4", validUser, validUser, defaultSSHPort, timeouts)
+	if err != nil {
+		t.Errorf("Failed to instantiate bmc: %v", err)
+	}
+
+	const expectedErrMsg = `failed to connect to CLI: failed to connect to BMC's SSH server: ` +
+		`dial tcp 1.2.3.4:22: i/o timeout`
+
+	_, _, err = bmc.RunCLICommand("help", false, 5*time.Second)
+	if err == nil {
+		t.Errorf("Err should not be nil.")
+	} else if err.Error() != expectedErrMsg {
+		t.Errorf("Unexpected error. Expected %v, Got: %v", expectedErrMsg, err.Error())
+	}
+}
+
+func Test_BMCSerialConsole(t *testing.T) {
+	timeouts := TimeOuts{Redfish: 1 * time.Second, SSH: 10 * time.Millisecond}
+
+	bmc, err := New("1.2.3.4", validUser, validUser, defaultSSHPort, timeouts)
+	if err != nil {
+		t.Errorf("Failed to instantiate bmc: %v", err)
+	}
+
+	var expectedErrMsg = `failed to create underlying ssh session for 1.2.3.4: ` +
+		`failed to connect to BMC's SSH server: dial tcp 1.2.3.4:22: i/o timeout`
+
+	_, _, err = bmc.OpenSerialConsole("console com2")
+	if err == nil {
+		t.Errorf("Err should not be nil.")
+	} else if err.Error() != expectedErrMsg {
+		t.Errorf("Unexpected error. Expected %v, Got: %v", expectedErrMsg, err.Error())
+	}
+
+	// Test without cli command... A best effort is made to open it based on system's manufacturer.
+	expectedErrMsg = `failed to get redfish system manufacturer for 1.2.3.4: redfish connection error: ` +
+		`failed to connect to redfish endpoint: Get "https://1.2.3.4/redfish/v1/": context deadline exceeded`
+
+	_, _, err = bmc.OpenSerialConsole("")
+	if err == nil {
+		t.Errorf("Err should not be nil.")
+	} else if err.Error() != expectedErrMsg {
+		t.Errorf("Unexpected error. Expected %v, Got: %v", expectedErrMsg, err.Error())
+	}
+
+	expectedErrMsg = "no underlying ssh session found for 1.2.3.4"
+
+	err = bmc.CloseSerialConsole()
+	if err == nil {
+		t.Errorf("Err should not be nil.")
+	} else if err.Error() != expectedErrMsg {
+		t.Errorf("Unexpected error. Expected %v, Got: %v", expectedErrMsg, err.Error())
+	}
+}
diff --git a/usage/bmc/bmc.go b/usage/bmc/bmc.go
index 6bd7cc4de..de2988963 100644
--- a/usage/bmc/bmc.go
+++ b/usage/bmc/bmc.go
@@ -1,9 +1,12 @@
 package main
 
 import (
+	"bufio"
 	"flag"
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 	"time"
 
 	"github.com/openshift-kni/eco-goinfra/pkg/bmc"
@@ -14,12 +17,81 @@ var (
 	hostFlag        *string        = flag.String("host", "", "RedFish host name/ip")
 	sshUserFlag     *string        = flag.String("sshuser", "", "SSH user's name")
 	sshPassFlag     *string        = flag.String("sshpass", "", "SSH user's password")
+	sshPortFlag     *uint          = flag.Uint("sshport", 22, "SSH port")
 	redfishUserFlag *string        = flag.String("redfishuser", "", "Redfish user's name")
 	redfishPassFlag *string        = flag.String("redfishpass", "", "Redfish user's password")
 	timeoutFlag     *time.Duration = flag.Duration("timeout", 0, "Timeout (1s, 1m30s, ...)")
-	systemIndex     *int           = flag.Int("system-index", 0, "Redfish system index")
+	systemIndexFlag *int           = flag.Int("system-index", 0, "Redfish system index")
+
+	// Defaulted to false. If set, it will open the serial console at the end.
+	testSerialConsoleFlag *bool = flag.Bool("serialconsoletest", false, "Read the Serial Console for 10s")
 )
 
+// runCLICommand is a helper funct to run cli commands and print some traces.
+func runCLICommand(bmc *bmc.BMC, cmd string, combineOutput bool, timeout time.Duration) {
+	fmt.Printf("%v - Running CLI command %q:\n", time.Now(), cmd)
+
+	stdout, stderr, err := bmc.RunCLICommand(cmd, combineOutput, timeout)
+	if err != nil {
+		fmt.Printf("%v - Failed to run cmd: %v\n", time.Now(), err)
+	}
+
+	fmt.Printf("%v\nstdout:\n%v\nstderr:%v\n", time.Now(), stdout, stderr)
+}
+
+func testSerialConsole(bmc *bmc.BMC, readTime time.Duration) {
+	reader, writer, err := bmc.OpenSerialConsole("")
+	if err != nil {
+		fmt.Printf("Failed to open serial console: %v", err)
+		os.Exit(1)
+	}
+
+	exitFn := func(reason string) {
+		fmt.Printf("\n%s -> Closing serial port...\n", reason)
+
+		_ = bmc.CloseSerialConsole()
+	}
+
+	signalCh := make(chan os.Signal, 1)
+	signal.Notify(signalCh, os.Interrupt, syscall.SIGTERM)
+
+	go func() {
+		<-signalCh
+		exitFn("CTRL+C captured")
+		os.Exit(1)
+	}()
+
+	defer exitFn("Normal exit")
+
+	// Close serialconsole's input.
+	_ = writer.Close()
+
+	fmt.Printf("Reading from Serial Console obtained...\n")
+
+	go func() {
+		scanner := bufio.NewScanner(reader)
+
+		for {
+			if !scanner.Scan() {
+				time.Sleep(1 * time.Second)
+
+				continue
+			}
+
+			if scanner.Err() != nil {
+				fmt.Printf("Scanner error: %v", scanner.Err())
+
+				break
+			}
+
+			line := scanner.Text()
+			fmt.Printf("%v\n", line)
+		}
+	}()
+
+	time.Sleep(readTime)
+}
+
 // Use cli flags to create a BMC struct and get the system's manufacturer and secure boot status.
 // timeout flag is optional. If not provided, it's defaulted to bmc.DefaultTimeouts.
 // systemIndex flag is optional. If not provided, it's defaulted to 0.
@@ -38,13 +110,13 @@ func main() {
 
 	fmt.Printf("Getting redfish information from host %s, timeouts: %+v\n", *hostFlag, timeOuts)
 
-	bmc, err := bmc.New(*hostFlag, redfishUser, sshUser, timeOuts)
+	bmc, err := bmc.New(*hostFlag, redfishUser, sshUser, uint16(*sshPortFlag), timeOuts)
 	if err != nil {
 		fmt.Printf("Failed to create BMC struct: %v\n", err)
 		os.Exit(1)
 	}
 
-	err = bmc.SetSystemIndex(*systemIndex)
+	err = bmc.SetSystemIndex(*systemIndexFlag)
 	if err != nil {
 		fmt.Printf("Failed to set system index: %v\n", err)
 		os.Exit(1)
@@ -61,6 +133,21 @@ func main() {
 		fmt.Printf("Failed to get secure boot status on %v: %v\n", *hostFlag, err)
 	}
 
-	fmt.Printf("System %d Manufacturer       : %v\n", *systemIndex, manufacturer)
-	fmt.Printf("System %d SecureBoot enabled : %v\n", *systemIndex, sbEnabled)
+	fmt.Printf("System %d Manufacturer       : %v\n", *systemIndexFlag, manufacturer)
+	fmt.Printf("System %d SecureBoot enabled : %v\n", *systemIndexFlag, sbEnabled)
+
+	// Run the help command. We should see all the available CLI commands.
+	runCLICommand(bmc, "help", true, 10*time.Second)
+
+	// Run an invalid command.
+	runCLICommand(bmc, "wrongcommand", true, 10*time.Second)
+
+	// Another wrong command, but in this case we want to force a timeout.
+	runCLICommand(bmc, "anotherwrongcommand", false, 1*time.Millisecond)
+
+	// The rest of the code tests the ssh-tunneled serial console.
+	if *testSerialConsoleFlag {
+		fmt.Printf("Reading from Serial Console for 10 seconds. Use ctrl+c to stop it...\n")
+		testSerialConsole(bmc, 10*time.Second)
+	}
 }
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_arm64.go b/vendor/golang.org/x/crypto/chacha20/chacha_arm64.go
new file mode 100644
index 000000000..661ea132e
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_arm64.go
@@ -0,0 +1,16 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+package chacha20
+
+const bufSize = 256
+
+//go:noescape
+func xorKeyStreamVX(dst, src []byte, key *[8]uint32, nonce *[3]uint32, counter *uint32)
+
+func (c *Cipher) xorKeyStreamBlocks(dst, src []byte) {
+	xorKeyStreamVX(dst, src, &c.key, &c.nonce, &c.counter)
+}
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_arm64.s b/vendor/golang.org/x/crypto/chacha20/chacha_arm64.s
new file mode 100644
index 000000000..7dd2638e8
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_arm64.s
@@ -0,0 +1,307 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+#include "textflag.h"
+
+#define NUM_ROUNDS 10
+
+// func xorKeyStreamVX(dst, src []byte, key *[8]uint32, nonce *[3]uint32, counter *uint32)
+TEXT ·xorKeyStreamVX(SB), NOSPLIT, $0
+	MOVD	dst+0(FP), R1
+	MOVD	src+24(FP), R2
+	MOVD	src_len+32(FP), R3
+	MOVD	key+48(FP), R4
+	MOVD	nonce+56(FP), R6
+	MOVD	counter+64(FP), R7
+
+	MOVD	$·constants(SB), R10
+	MOVD	$·incRotMatrix(SB), R11
+
+	MOVW	(R7), R20
+
+	AND	$~255, R3, R13
+	ADD	R2, R13, R12 // R12 for block end
+	AND	$255, R3, R13
+loop:
+	MOVD	$NUM_ROUNDS, R21
+	VLD1	(R11), [V30.S4, V31.S4]
+
+	// load contants
+	// VLD4R (R10), [V0.S4, V1.S4, V2.S4, V3.S4]
+	WORD	$0x4D60E940
+
+	// load keys
+	// VLD4R 16(R4), [V4.S4, V5.S4, V6.S4, V7.S4]
+	WORD	$0x4DFFE884
+	// VLD4R 16(R4), [V8.S4, V9.S4, V10.S4, V11.S4]
+	WORD	$0x4DFFE888
+	SUB	$32, R4
+
+	// load counter + nonce
+	// VLD1R (R7), [V12.S4]
+	WORD	$0x4D40C8EC
+
+	// VLD3R (R6), [V13.S4, V14.S4, V15.S4]
+	WORD	$0x4D40E8CD
+
+	// update counter
+	VADD	V30.S4, V12.S4, V12.S4
+
+chacha:
+	// V0..V3 += V4..V7
+	// V12..V15 <<<= ((V12..V15 XOR V0..V3), 16)
+	VADD	V0.S4, V4.S4, V0.S4
+	VADD	V1.S4, V5.S4, V1.S4
+	VADD	V2.S4, V6.S4, V2.S4
+	VADD	V3.S4, V7.S4, V3.S4
+	VEOR	V12.B16, V0.B16, V12.B16
+	VEOR	V13.B16, V1.B16, V13.B16
+	VEOR	V14.B16, V2.B16, V14.B16
+	VEOR	V15.B16, V3.B16, V15.B16
+	VREV32	V12.H8, V12.H8
+	VREV32	V13.H8, V13.H8
+	VREV32	V14.H8, V14.H8
+	VREV32	V15.H8, V15.H8
+	// V8..V11 += V12..V15
+	// V4..V7 <<<= ((V4..V7 XOR V8..V11), 12)
+	VADD	V8.S4, V12.S4, V8.S4
+	VADD	V9.S4, V13.S4, V9.S4
+	VADD	V10.S4, V14.S4, V10.S4
+	VADD	V11.S4, V15.S4, V11.S4
+	VEOR	V8.B16, V4.B16, V16.B16
+	VEOR	V9.B16, V5.B16, V17.B16
+	VEOR	V10.B16, V6.B16, V18.B16
+	VEOR	V11.B16, V7.B16, V19.B16
+	VSHL	$12, V16.S4, V4.S4
+	VSHL	$12, V17.S4, V5.S4
+	VSHL	$12, V18.S4, V6.S4
+	VSHL	$12, V19.S4, V7.S4
+	VSRI	$20, V16.S4, V4.S4
+	VSRI	$20, V17.S4, V5.S4
+	VSRI	$20, V18.S4, V6.S4
+	VSRI	$20, V19.S4, V7.S4
+
+	// V0..V3 += V4..V7
+	// V12..V15 <<<= ((V12..V15 XOR V0..V3), 8)
+	VADD	V0.S4, V4.S4, V0.S4
+	VADD	V1.S4, V5.S4, V1.S4
+	VADD	V2.S4, V6.S4, V2.S4
+	VADD	V3.S4, V7.S4, V3.S4
+	VEOR	V12.B16, V0.B16, V12.B16
+	VEOR	V13.B16, V1.B16, V13.B16
+	VEOR	V14.B16, V2.B16, V14.B16
+	VEOR	V15.B16, V3.B16, V15.B16
+	VTBL	V31.B16, [V12.B16], V12.B16
+	VTBL	V31.B16, [V13.B16], V13.B16
+	VTBL	V31.B16, [V14.B16], V14.B16
+	VTBL	V31.B16, [V15.B16], V15.B16
+
+	// V8..V11 += V12..V15
+	// V4..V7 <<<= ((V4..V7 XOR V8..V11), 7)
+	VADD	V12.S4, V8.S4, V8.S4
+	VADD	V13.S4, V9.S4, V9.S4
+	VADD	V14.S4, V10.S4, V10.S4
+	VADD	V15.S4, V11.S4, V11.S4
+	VEOR	V8.B16, V4.B16, V16.B16
+	VEOR	V9.B16, V5.B16, V17.B16
+	VEOR	V10.B16, V6.B16, V18.B16
+	VEOR	V11.B16, V7.B16, V19.B16
+	VSHL	$7, V16.S4, V4.S4
+	VSHL	$7, V17.S4, V5.S4
+	VSHL	$7, V18.S4, V6.S4
+	VSHL	$7, V19.S4, V7.S4
+	VSRI	$25, V16.S4, V4.S4
+	VSRI	$25, V17.S4, V5.S4
+	VSRI	$25, V18.S4, V6.S4
+	VSRI	$25, V19.S4, V7.S4
+
+	// V0..V3 += V5..V7, V4
+	// V15,V12-V14 <<<= ((V15,V12-V14 XOR V0..V3), 16)
+	VADD	V0.S4, V5.S4, V0.S4
+	VADD	V1.S4, V6.S4, V1.S4
+	VADD	V2.S4, V7.S4, V2.S4
+	VADD	V3.S4, V4.S4, V3.S4
+	VEOR	V15.B16, V0.B16, V15.B16
+	VEOR	V12.B16, V1.B16, V12.B16
+	VEOR	V13.B16, V2.B16, V13.B16
+	VEOR	V14.B16, V3.B16, V14.B16
+	VREV32	V12.H8, V12.H8
+	VREV32	V13.H8, V13.H8
+	VREV32	V14.H8, V14.H8
+	VREV32	V15.H8, V15.H8
+
+	// V10 += V15; V5 <<<= ((V10 XOR V5), 12)
+	// ...
+	VADD	V15.S4, V10.S4, V10.S4
+	VADD	V12.S4, V11.S4, V11.S4
+	VADD	V13.S4, V8.S4, V8.S4
+	VADD	V14.S4, V9.S4, V9.S4
+	VEOR	V10.B16, V5.B16, V16.B16
+	VEOR	V11.B16, V6.B16, V17.B16
+	VEOR	V8.B16, V7.B16, V18.B16
+	VEOR	V9.B16, V4.B16, V19.B16
+	VSHL	$12, V16.S4, V5.S4
+	VSHL	$12, V17.S4, V6.S4
+	VSHL	$12, V18.S4, V7.S4
+	VSHL	$12, V19.S4, V4.S4
+	VSRI	$20, V16.S4, V5.S4
+	VSRI	$20, V17.S4, V6.S4
+	VSRI	$20, V18.S4, V7.S4
+	VSRI	$20, V19.S4, V4.S4
+
+	// V0 += V5; V15 <<<= ((V0 XOR V15), 8)
+	// ...
+	VADD	V5.S4, V0.S4, V0.S4
+	VADD	V6.S4, V1.S4, V1.S4
+	VADD	V7.S4, V2.S4, V2.S4
+	VADD	V4.S4, V3.S4, V3.S4
+	VEOR	V0.B16, V15.B16, V15.B16
+	VEOR	V1.B16, V12.B16, V12.B16
+	VEOR	V2.B16, V13.B16, V13.B16
+	VEOR	V3.B16, V14.B16, V14.B16
+	VTBL	V31.B16, [V12.B16], V12.B16
+	VTBL	V31.B16, [V13.B16], V13.B16
+	VTBL	V31.B16, [V14.B16], V14.B16
+	VTBL	V31.B16, [V15.B16], V15.B16
+
+	// V10 += V15; V5 <<<= ((V10 XOR V5), 7)
+	// ...
+	VADD	V15.S4, V10.S4, V10.S4
+	VADD	V12.S4, V11.S4, V11.S4
+	VADD	V13.S4, V8.S4, V8.S4
+	VADD	V14.S4, V9.S4, V9.S4
+	VEOR	V10.B16, V5.B16, V16.B16
+	VEOR	V11.B16, V6.B16, V17.B16
+	VEOR	V8.B16, V7.B16, V18.B16
+	VEOR	V9.B16, V4.B16, V19.B16
+	VSHL	$7, V16.S4, V5.S4
+	VSHL	$7, V17.S4, V6.S4
+	VSHL	$7, V18.S4, V7.S4
+	VSHL	$7, V19.S4, V4.S4
+	VSRI	$25, V16.S4, V5.S4
+	VSRI	$25, V17.S4, V6.S4
+	VSRI	$25, V18.S4, V7.S4
+	VSRI	$25, V19.S4, V4.S4
+
+	SUB	$1, R21
+	CBNZ	R21, chacha
+
+	// VLD4R (R10), [V16.S4, V17.S4, V18.S4, V19.S4]
+	WORD	$0x4D60E950
+
+	// VLD4R 16(R4), [V20.S4, V21.S4, V22.S4, V23.S4]
+	WORD	$0x4DFFE894
+	VADD	V30.S4, V12.S4, V12.S4
+	VADD	V16.S4, V0.S4, V0.S4
+	VADD	V17.S4, V1.S4, V1.S4
+	VADD	V18.S4, V2.S4, V2.S4
+	VADD	V19.S4, V3.S4, V3.S4
+	// VLD4R 16(R4), [V24.S4, V25.S4, V26.S4, V27.S4]
+	WORD	$0x4DFFE898
+	// restore R4
+	SUB	$32, R4
+
+	// load counter + nonce
+	// VLD1R (R7), [V28.S4]
+	WORD	$0x4D40C8FC
+	// VLD3R (R6), [V29.S4, V30.S4, V31.S4]
+	WORD	$0x4D40E8DD
+
+	VADD	V20.S4, V4.S4, V4.S4
+	VADD	V21.S4, V5.S4, V5.S4
+	VADD	V22.S4, V6.S4, V6.S4
+	VADD	V23.S4, V7.S4, V7.S4
+	VADD	V24.S4, V8.S4, V8.S4
+	VADD	V25.S4, V9.S4, V9.S4
+	VADD	V26.S4, V10.S4, V10.S4
+	VADD	V27.S4, V11.S4, V11.S4
+	VADD	V28.S4, V12.S4, V12.S4
+	VADD	V29.S4, V13.S4, V13.S4
+	VADD	V30.S4, V14.S4, V14.S4
+	VADD	V31.S4, V15.S4, V15.S4
+
+	VZIP1	V1.S4, V0.S4, V16.S4
+	VZIP2	V1.S4, V0.S4, V17.S4
+	VZIP1	V3.S4, V2.S4, V18.S4
+	VZIP2	V3.S4, V2.S4, V19.S4
+	VZIP1	V5.S4, V4.S4, V20.S4
+	VZIP2	V5.S4, V4.S4, V21.S4
+	VZIP1	V7.S4, V6.S4, V22.S4
+	VZIP2	V7.S4, V6.S4, V23.S4
+	VZIP1	V9.S4, V8.S4, V24.S4
+	VZIP2	V9.S4, V8.S4, V25.S4
+	VZIP1	V11.S4, V10.S4, V26.S4
+	VZIP2	V11.S4, V10.S4, V27.S4
+	VZIP1	V13.S4, V12.S4, V28.S4
+	VZIP2	V13.S4, V12.S4, V29.S4
+	VZIP1	V15.S4, V14.S4, V30.S4
+	VZIP2	V15.S4, V14.S4, V31.S4
+	VZIP1	V18.D2, V16.D2, V0.D2
+	VZIP2	V18.D2, V16.D2, V4.D2
+	VZIP1	V19.D2, V17.D2, V8.D2
+	VZIP2	V19.D2, V17.D2, V12.D2
+	VLD1.P	64(R2), [V16.B16, V17.B16, V18.B16, V19.B16]
+
+	VZIP1	V22.D2, V20.D2, V1.D2
+	VZIP2	V22.D2, V20.D2, V5.D2
+	VZIP1	V23.D2, V21.D2, V9.D2
+	VZIP2	V23.D2, V21.D2, V13.D2
+	VLD1.P	64(R2), [V20.B16, V21.B16, V22.B16, V23.B16]
+	VZIP1	V26.D2, V24.D2, V2.D2
+	VZIP2	V26.D2, V24.D2, V6.D2
+	VZIP1	V27.D2, V25.D2, V10.D2
+	VZIP2	V27.D2, V25.D2, V14.D2
+	VLD1.P	64(R2), [V24.B16, V25.B16, V26.B16, V27.B16]
+	VZIP1	V30.D2, V28.D2, V3.D2
+	VZIP2	V30.D2, V28.D2, V7.D2
+	VZIP1	V31.D2, V29.D2, V11.D2
+	VZIP2	V31.D2, V29.D2, V15.D2
+	VLD1.P	64(R2), [V28.B16, V29.B16, V30.B16, V31.B16]
+	VEOR	V0.B16, V16.B16, V16.B16
+	VEOR	V1.B16, V17.B16, V17.B16
+	VEOR	V2.B16, V18.B16, V18.B16
+	VEOR	V3.B16, V19.B16, V19.B16
+	VST1.P	[V16.B16, V17.B16, V18.B16, V19.B16], 64(R1)
+	VEOR	V4.B16, V20.B16, V20.B16
+	VEOR	V5.B16, V21.B16, V21.B16
+	VEOR	V6.B16, V22.B16, V22.B16
+	VEOR	V7.B16, V23.B16, V23.B16
+	VST1.P	[V20.B16, V21.B16, V22.B16, V23.B16], 64(R1)
+	VEOR	V8.B16, V24.B16, V24.B16
+	VEOR	V9.B16, V25.B16, V25.B16
+	VEOR	V10.B16, V26.B16, V26.B16
+	VEOR	V11.B16, V27.B16, V27.B16
+	VST1.P	[V24.B16, V25.B16, V26.B16, V27.B16], 64(R1)
+	VEOR	V12.B16, V28.B16, V28.B16
+	VEOR	V13.B16, V29.B16, V29.B16
+	VEOR	V14.B16, V30.B16, V30.B16
+	VEOR	V15.B16, V31.B16, V31.B16
+	VST1.P	[V28.B16, V29.B16, V30.B16, V31.B16], 64(R1)
+
+	ADD	$4, R20
+	MOVW	R20, (R7) // update counter
+
+	CMP	R2, R12
+	BGT	loop
+
+	RET
+
+
+DATA	·constants+0x00(SB)/4, $0x61707865
+DATA	·constants+0x04(SB)/4, $0x3320646e
+DATA	·constants+0x08(SB)/4, $0x79622d32
+DATA	·constants+0x0c(SB)/4, $0x6b206574
+GLOBL	·constants(SB), NOPTR|RODATA, $32
+
+DATA	·incRotMatrix+0x00(SB)/4, $0x00000000
+DATA	·incRotMatrix+0x04(SB)/4, $0x00000001
+DATA	·incRotMatrix+0x08(SB)/4, $0x00000002
+DATA	·incRotMatrix+0x0c(SB)/4, $0x00000003
+DATA	·incRotMatrix+0x10(SB)/4, $0x02010003
+DATA	·incRotMatrix+0x14(SB)/4, $0x06050407
+DATA	·incRotMatrix+0x18(SB)/4, $0x0A09080B
+DATA	·incRotMatrix+0x1c(SB)/4, $0x0E0D0C0F
+GLOBL	·incRotMatrix(SB), NOPTR|RODATA, $32
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_generic.go b/vendor/golang.org/x/crypto/chacha20/chacha_generic.go
new file mode 100644
index 000000000..93eb5ae6d
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_generic.go
@@ -0,0 +1,398 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package chacha20 implements the ChaCha20 and XChaCha20 encryption algorithms
+// as specified in RFC 8439 and draft-irtf-cfrg-xchacha-01.
+package chacha20
+
+import (
+	"crypto/cipher"
+	"encoding/binary"
+	"errors"
+	"math/bits"
+
+	"golang.org/x/crypto/internal/alias"
+)
+
+const (
+	// KeySize is the size of the key used by this cipher, in bytes.
+	KeySize = 32
+
+	// NonceSize is the size of the nonce used with the standard variant of this
+	// cipher, in bytes.
+	//
+	// Note that this is too short to be safely generated at random if the same
+	// key is reused more than 2³² times.
+	NonceSize = 12
+
+	// NonceSizeX is the size of the nonce used with the XChaCha20 variant of
+	// this cipher, in bytes.
+	NonceSizeX = 24
+)
+
+// Cipher is a stateful instance of ChaCha20 or XChaCha20 using a particular key
+// and nonce. A *Cipher implements the cipher.Stream interface.
+type Cipher struct {
+	// The ChaCha20 state is 16 words: 4 constant, 8 of key, 1 of counter
+	// (incremented after each block), and 3 of nonce.
+	key     [8]uint32
+	counter uint32
+	nonce   [3]uint32
+
+	// The last len bytes of buf are leftover key stream bytes from the previous
+	// XORKeyStream invocation. The size of buf depends on how many blocks are
+	// computed at a time by xorKeyStreamBlocks.
+	buf [bufSize]byte
+	len int
+
+	// overflow is set when the counter overflowed, no more blocks can be
+	// generated, and the next XORKeyStream call should panic.
+	overflow bool
+
+	// The counter-independent results of the first round are cached after they
+	// are computed the first time.
+	precompDone      bool
+	p1, p5, p9, p13  uint32
+	p2, p6, p10, p14 uint32
+	p3, p7, p11, p15 uint32
+}
+
+var _ cipher.Stream = (*Cipher)(nil)
+
+// NewUnauthenticatedCipher creates a new ChaCha20 stream cipher with the given
+// 32 bytes key and a 12 or 24 bytes nonce. If a nonce of 24 bytes is provided,
+// the XChaCha20 construction will be used. It returns an error if key or nonce
+// have any other length.
+//
+// Note that ChaCha20, like all stream ciphers, is not authenticated and allows
+// attackers to silently tamper with the plaintext. For this reason, it is more
+// appropriate as a building block than as a standalone encryption mechanism.
+// Instead, consider using package golang.org/x/crypto/chacha20poly1305.
+func NewUnauthenticatedCipher(key, nonce []byte) (*Cipher, error) {
+	// This function is split into a wrapper so that the Cipher allocation will
+	// be inlined, and depending on how the caller uses the return value, won't
+	// escape to the heap.
+	c := &Cipher{}
+	return newUnauthenticatedCipher(c, key, nonce)
+}
+
+func newUnauthenticatedCipher(c *Cipher, key, nonce []byte) (*Cipher, error) {
+	if len(key) != KeySize {
+		return nil, errors.New("chacha20: wrong key size")
+	}
+	if len(nonce) == NonceSizeX {
+		// XChaCha20 uses the ChaCha20 core to mix 16 bytes of the nonce into a
+		// derived key, allowing it to operate on a nonce of 24 bytes. See
+		// draft-irtf-cfrg-xchacha-01, Section 2.3.
+		key, _ = HChaCha20(key, nonce[0:16])
+		cNonce := make([]byte, NonceSize)
+		copy(cNonce[4:12], nonce[16:24])
+		nonce = cNonce
+	} else if len(nonce) != NonceSize {
+		return nil, errors.New("chacha20: wrong nonce size")
+	}
+
+	key, nonce = key[:KeySize], nonce[:NonceSize] // bounds check elimination hint
+	c.key = [8]uint32{
+		binary.LittleEndian.Uint32(key[0:4]),
+		binary.LittleEndian.Uint32(key[4:8]),
+		binary.LittleEndian.Uint32(key[8:12]),
+		binary.LittleEndian.Uint32(key[12:16]),
+		binary.LittleEndian.Uint32(key[16:20]),
+		binary.LittleEndian.Uint32(key[20:24]),
+		binary.LittleEndian.Uint32(key[24:28]),
+		binary.LittleEndian.Uint32(key[28:32]),
+	}
+	c.nonce = [3]uint32{
+		binary.LittleEndian.Uint32(nonce[0:4]),
+		binary.LittleEndian.Uint32(nonce[4:8]),
+		binary.LittleEndian.Uint32(nonce[8:12]),
+	}
+	return c, nil
+}
+
+// The constant first 4 words of the ChaCha20 state.
+const (
+	j0 uint32 = 0x61707865 // expa
+	j1 uint32 = 0x3320646e // nd 3
+	j2 uint32 = 0x79622d32 // 2-by
+	j3 uint32 = 0x6b206574 // te k
+)
+
+const blockSize = 64
+
+// quarterRound is the core of ChaCha20. It shuffles the bits of 4 state words.
+// It's executed 4 times for each of the 20 ChaCha20 rounds, operating on all 16
+// words each round, in columnar or diagonal groups of 4 at a time.
+func quarterRound(a, b, c, d uint32) (uint32, uint32, uint32, uint32) {
+	a += b
+	d ^= a
+	d = bits.RotateLeft32(d, 16)
+	c += d
+	b ^= c
+	b = bits.RotateLeft32(b, 12)
+	a += b
+	d ^= a
+	d = bits.RotateLeft32(d, 8)
+	c += d
+	b ^= c
+	b = bits.RotateLeft32(b, 7)
+	return a, b, c, d
+}
+
+// SetCounter sets the Cipher counter. The next invocation of XORKeyStream will
+// behave as if (64 * counter) bytes had been encrypted so far.
+//
+// To prevent accidental counter reuse, SetCounter panics if counter is less
+// than the current value.
+//
+// Note that the execution time of XORKeyStream is not independent of the
+// counter value.
+func (s *Cipher) SetCounter(counter uint32) {
+	// Internally, s may buffer multiple blocks, which complicates this
+	// implementation slightly. When checking whether the counter has rolled
+	// back, we must use both s.counter and s.len to determine how many blocks
+	// we have already output.
+	outputCounter := s.counter - uint32(s.len)/blockSize
+	if s.overflow || counter < outputCounter {
+		panic("chacha20: SetCounter attempted to rollback counter")
+	}
+
+	// In the general case, we set the new counter value and reset s.len to 0,
+	// causing the next call to XORKeyStream to refill the buffer. However, if
+	// we're advancing within the existing buffer, we can save work by simply
+	// setting s.len.
+	if counter < s.counter {
+		s.len = int(s.counter-counter) * blockSize
+	} else {
+		s.counter = counter
+		s.len = 0
+	}
+}
+
+// XORKeyStream XORs each byte in the given slice with a byte from the
+// cipher's key stream. Dst and src must overlap entirely or not at all.
+//
+// If len(dst) < len(src), XORKeyStream will panic. It is acceptable
+// to pass a dst bigger than src, and in that case, XORKeyStream will
+// only update dst[:len(src)] and will not touch the rest of dst.
+//
+// Multiple calls to XORKeyStream behave as if the concatenation of
+// the src buffers was passed in a single run. That is, Cipher
+// maintains state and does not reset at each XORKeyStream call.
+func (s *Cipher) XORKeyStream(dst, src []byte) {
+	if len(src) == 0 {
+		return
+	}
+	if len(dst) < len(src) {
+		panic("chacha20: output smaller than input")
+	}
+	dst = dst[:len(src)]
+	if alias.InexactOverlap(dst, src) {
+		panic("chacha20: invalid buffer overlap")
+	}
+
+	// First, drain any remaining key stream from a previous XORKeyStream.
+	if s.len != 0 {
+		keyStream := s.buf[bufSize-s.len:]
+		if len(src) < len(keyStream) {
+			keyStream = keyStream[:len(src)]
+		}
+		_ = src[len(keyStream)-1] // bounds check elimination hint
+		for i, b := range keyStream {
+			dst[i] = src[i] ^ b
+		}
+		s.len -= len(keyStream)
+		dst, src = dst[len(keyStream):], src[len(keyStream):]
+	}
+	if len(src) == 0 {
+		return
+	}
+
+	// If we'd need to let the counter overflow and keep generating output,
+	// panic immediately. If instead we'd only reach the last block, remember
+	// not to generate any more output after the buffer is drained.
+	numBlocks := (uint64(len(src)) + blockSize - 1) / blockSize
+	if s.overflow || uint64(s.counter)+numBlocks > 1<<32 {
+		panic("chacha20: counter overflow")
+	} else if uint64(s.counter)+numBlocks == 1<<32 {
+		s.overflow = true
+	}
+
+	// xorKeyStreamBlocks implementations expect input lengths that are a
+	// multiple of bufSize. Platform-specific ones process multiple blocks at a
+	// time, so have bufSizes that are a multiple of blockSize.
+
+	full := len(src) - len(src)%bufSize
+	if full > 0 {
+		s.xorKeyStreamBlocks(dst[:full], src[:full])
+	}
+	dst, src = dst[full:], src[full:]
+
+	// If using a multi-block xorKeyStreamBlocks would overflow, use the generic
+	// one that does one block at a time.
+	const blocksPerBuf = bufSize / blockSize
+	if uint64(s.counter)+blocksPerBuf > 1<<32 {
+		s.buf = [bufSize]byte{}
+		numBlocks := (len(src) + blockSize - 1) / blockSize
+		buf := s.buf[bufSize-numBlocks*blockSize:]
+		copy(buf, src)
+		s.xorKeyStreamBlocksGeneric(buf, buf)
+		s.len = len(buf) - copy(dst, buf)
+		return
+	}
+
+	// If we have a partial (multi-)block, pad it for xorKeyStreamBlocks, and
+	// keep the leftover keystream for the next XORKeyStream invocation.
+	if len(src) > 0 {
+		s.buf = [bufSize]byte{}
+		copy(s.buf[:], src)
+		s.xorKeyStreamBlocks(s.buf[:], s.buf[:])
+		s.len = bufSize - copy(dst, s.buf[:])
+	}
+}
+
+func (s *Cipher) xorKeyStreamBlocksGeneric(dst, src []byte) {
+	if len(dst) != len(src) || len(dst)%blockSize != 0 {
+		panic("chacha20: internal error: wrong dst and/or src length")
+	}
+
+	// To generate each block of key stream, the initial cipher state
+	// (represented below) is passed through 20 rounds of shuffling,
+	// alternatively applying quarterRounds by columns (like 1, 5, 9, 13)
+	// or by diagonals (like 1, 6, 11, 12).
+	//
+	//      0:cccccccc   1:cccccccc   2:cccccccc   3:cccccccc
+	//      4:kkkkkkkk   5:kkkkkkkk   6:kkkkkkkk   7:kkkkkkkk
+	//      8:kkkkkkkk   9:kkkkkkkk  10:kkkkkkkk  11:kkkkkkkk
+	//     12:bbbbbbbb  13:nnnnnnnn  14:nnnnnnnn  15:nnnnnnnn
+	//
+	//            c=constant k=key b=blockcount n=nonce
+	var (
+		c0, c1, c2, c3   = j0, j1, j2, j3
+		c4, c5, c6, c7   = s.key[0], s.key[1], s.key[2], s.key[3]
+		c8, c9, c10, c11 = s.key[4], s.key[5], s.key[6], s.key[7]
+		_, c13, c14, c15 = s.counter, s.nonce[0], s.nonce[1], s.nonce[2]
+	)
+
+	// Three quarters of the first round don't depend on the counter, so we can
+	// calculate them here, and reuse them for multiple blocks in the loop, and
+	// for future XORKeyStream invocations.
+	if !s.precompDone {
+		s.p1, s.p5, s.p9, s.p13 = quarterRound(c1, c5, c9, c13)
+		s.p2, s.p6, s.p10, s.p14 = quarterRound(c2, c6, c10, c14)
+		s.p3, s.p7, s.p11, s.p15 = quarterRound(c3, c7, c11, c15)
+		s.precompDone = true
+	}
+
+	// A condition of len(src) > 0 would be sufficient, but this also
+	// acts as a bounds check elimination hint.
+	for len(src) >= 64 && len(dst) >= 64 {
+		// The remainder of the first column round.
+		fcr0, fcr4, fcr8, fcr12 := quarterRound(c0, c4, c8, s.counter)
+
+		// The second diagonal round.
+		x0, x5, x10, x15 := quarterRound(fcr0, s.p5, s.p10, s.p15)
+		x1, x6, x11, x12 := quarterRound(s.p1, s.p6, s.p11, fcr12)
+		x2, x7, x8, x13 := quarterRound(s.p2, s.p7, fcr8, s.p13)
+		x3, x4, x9, x14 := quarterRound(s.p3, fcr4, s.p9, s.p14)
+
+		// The remaining 18 rounds.
+		for i := 0; i < 9; i++ {
+			// Column round.
+			x0, x4, x8, x12 = quarterRound(x0, x4, x8, x12)
+			x1, x5, x9, x13 = quarterRound(x1, x5, x9, x13)
+			x2, x6, x10, x14 = quarterRound(x2, x6, x10, x14)
+			x3, x7, x11, x15 = quarterRound(x3, x7, x11, x15)
+
+			// Diagonal round.
+			x0, x5, x10, x15 = quarterRound(x0, x5, x10, x15)
+			x1, x6, x11, x12 = quarterRound(x1, x6, x11, x12)
+			x2, x7, x8, x13 = quarterRound(x2, x7, x8, x13)
+			x3, x4, x9, x14 = quarterRound(x3, x4, x9, x14)
+		}
+
+		// Add back the initial state to generate the key stream, then
+		// XOR the key stream with the source and write out the result.
+		addXor(dst[0:4], src[0:4], x0, c0)
+		addXor(dst[4:8], src[4:8], x1, c1)
+		addXor(dst[8:12], src[8:12], x2, c2)
+		addXor(dst[12:16], src[12:16], x3, c3)
+		addXor(dst[16:20], src[16:20], x4, c4)
+		addXor(dst[20:24], src[20:24], x5, c5)
+		addXor(dst[24:28], src[24:28], x6, c6)
+		addXor(dst[28:32], src[28:32], x7, c7)
+		addXor(dst[32:36], src[32:36], x8, c8)
+		addXor(dst[36:40], src[36:40], x9, c9)
+		addXor(dst[40:44], src[40:44], x10, c10)
+		addXor(dst[44:48], src[44:48], x11, c11)
+		addXor(dst[48:52], src[48:52], x12, s.counter)
+		addXor(dst[52:56], src[52:56], x13, c13)
+		addXor(dst[56:60], src[56:60], x14, c14)
+		addXor(dst[60:64], src[60:64], x15, c15)
+
+		s.counter += 1
+
+		src, dst = src[blockSize:], dst[blockSize:]
+	}
+}
+
+// HChaCha20 uses the ChaCha20 core to generate a derived key from a 32 bytes
+// key and a 16 bytes nonce. It returns an error if key or nonce have any other
+// length. It is used as part of the XChaCha20 construction.
+func HChaCha20(key, nonce []byte) ([]byte, error) {
+	// This function is split into a wrapper so that the slice allocation will
+	// be inlined, and depending on how the caller uses the return value, won't
+	// escape to the heap.
+	out := make([]byte, 32)
+	return hChaCha20(out, key, nonce)
+}
+
+func hChaCha20(out, key, nonce []byte) ([]byte, error) {
+	if len(key) != KeySize {
+		return nil, errors.New("chacha20: wrong HChaCha20 key size")
+	}
+	if len(nonce) != 16 {
+		return nil, errors.New("chacha20: wrong HChaCha20 nonce size")
+	}
+
+	x0, x1, x2, x3 := j0, j1, j2, j3
+	x4 := binary.LittleEndian.Uint32(key[0:4])
+	x5 := binary.LittleEndian.Uint32(key[4:8])
+	x6 := binary.LittleEndian.Uint32(key[8:12])
+	x7 := binary.LittleEndian.Uint32(key[12:16])
+	x8 := binary.LittleEndian.Uint32(key[16:20])
+	x9 := binary.LittleEndian.Uint32(key[20:24])
+	x10 := binary.LittleEndian.Uint32(key[24:28])
+	x11 := binary.LittleEndian.Uint32(key[28:32])
+	x12 := binary.LittleEndian.Uint32(nonce[0:4])
+	x13 := binary.LittleEndian.Uint32(nonce[4:8])
+	x14 := binary.LittleEndian.Uint32(nonce[8:12])
+	x15 := binary.LittleEndian.Uint32(nonce[12:16])
+
+	for i := 0; i < 10; i++ {
+		// Diagonal round.
+		x0, x4, x8, x12 = quarterRound(x0, x4, x8, x12)
+		x1, x5, x9, x13 = quarterRound(x1, x5, x9, x13)
+		x2, x6, x10, x14 = quarterRound(x2, x6, x10, x14)
+		x3, x7, x11, x15 = quarterRound(x3, x7, x11, x15)
+
+		// Column round.
+		x0, x5, x10, x15 = quarterRound(x0, x5, x10, x15)
+		x1, x6, x11, x12 = quarterRound(x1, x6, x11, x12)
+		x2, x7, x8, x13 = quarterRound(x2, x7, x8, x13)
+		x3, x4, x9, x14 = quarterRound(x3, x4, x9, x14)
+	}
+
+	_ = out[31] // bounds check elimination hint
+	binary.LittleEndian.PutUint32(out[0:4], x0)
+	binary.LittleEndian.PutUint32(out[4:8], x1)
+	binary.LittleEndian.PutUint32(out[8:12], x2)
+	binary.LittleEndian.PutUint32(out[12:16], x3)
+	binary.LittleEndian.PutUint32(out[16:20], x12)
+	binary.LittleEndian.PutUint32(out[20:24], x13)
+	binary.LittleEndian.PutUint32(out[24:28], x14)
+	binary.LittleEndian.PutUint32(out[28:32], x15)
+	return out, nil
+}
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_noasm.go b/vendor/golang.org/x/crypto/chacha20/chacha_noasm.go
new file mode 100644
index 000000000..db42e6676
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_noasm.go
@@ -0,0 +1,13 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (!arm64 && !s390x && !ppc64le) || !gc || purego
+
+package chacha20
+
+const bufSize = blockSize
+
+func (s *Cipher) xorKeyStreamBlocks(dst, src []byte) {
+	s.xorKeyStreamBlocksGeneric(dst, src)
+}
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.go b/vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.go
new file mode 100644
index 000000000..3a4287f99
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.go
@@ -0,0 +1,16 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+package chacha20
+
+const bufSize = 256
+
+//go:noescape
+func chaCha20_ctr32_vsx(out, inp *byte, len int, key *[8]uint32, counter *uint32)
+
+func (c *Cipher) xorKeyStreamBlocks(dst, src []byte) {
+	chaCha20_ctr32_vsx(&dst[0], &src[0], len(src), &c.key, &c.counter)
+}
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.s b/vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.s
new file mode 100644
index 000000000..c672ccf69
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.s
@@ -0,0 +1,443 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Based on CRYPTOGAMS code with the following comment:
+// # ====================================================================
+// # Written by Andy Polyakov <appro@openssl.org> for the OpenSSL
+// # project. The module is, however, dual licensed under OpenSSL and
+// # CRYPTOGAMS licenses depending on where you obtain it. For further
+// # details see http://www.openssl.org/~appro/cryptogams/.
+// # ====================================================================
+
+// Code for the perl script that generates the ppc64 assembler
+// can be found in the cryptogams repository at the link below. It is based on
+// the original from openssl.
+
+// https://github.com/dot-asm/cryptogams/commit/a60f5b50ed908e91
+
+// The differences in this and the original implementation are
+// due to the calling conventions and initialization of constants.
+
+//go:build gc && !purego
+
+#include "textflag.h"
+
+#define OUT  R3
+#define INP  R4
+#define LEN  R5
+#define KEY  R6
+#define CNT  R7
+#define TMP  R15
+
+#define CONSTBASE  R16
+#define BLOCKS R17
+
+// for VPERMXOR
+#define MASK  R18
+
+DATA consts<>+0x00(SB)/8, $0x3320646e61707865
+DATA consts<>+0x08(SB)/8, $0x6b20657479622d32
+DATA consts<>+0x10(SB)/8, $0x0000000000000001
+DATA consts<>+0x18(SB)/8, $0x0000000000000000
+DATA consts<>+0x20(SB)/8, $0x0000000000000004
+DATA consts<>+0x28(SB)/8, $0x0000000000000000
+DATA consts<>+0x30(SB)/8, $0x0a0b08090e0f0c0d
+DATA consts<>+0x38(SB)/8, $0x0203000106070405
+DATA consts<>+0x40(SB)/8, $0x090a0b080d0e0f0c
+DATA consts<>+0x48(SB)/8, $0x0102030005060704
+DATA consts<>+0x50(SB)/8, $0x6170786561707865
+DATA consts<>+0x58(SB)/8, $0x6170786561707865
+DATA consts<>+0x60(SB)/8, $0x3320646e3320646e
+DATA consts<>+0x68(SB)/8, $0x3320646e3320646e
+DATA consts<>+0x70(SB)/8, $0x79622d3279622d32
+DATA consts<>+0x78(SB)/8, $0x79622d3279622d32
+DATA consts<>+0x80(SB)/8, $0x6b2065746b206574
+DATA consts<>+0x88(SB)/8, $0x6b2065746b206574
+DATA consts<>+0x90(SB)/8, $0x0000000100000000
+DATA consts<>+0x98(SB)/8, $0x0000000300000002
+DATA consts<>+0xa0(SB)/8, $0x5566774411223300
+DATA consts<>+0xa8(SB)/8, $0xddeeffcc99aabb88
+DATA consts<>+0xb0(SB)/8, $0x6677445522330011
+DATA consts<>+0xb8(SB)/8, $0xeeffccddaabb8899
+GLOBL consts<>(SB), RODATA, $0xc0
+
+//func chaCha20_ctr32_vsx(out, inp *byte, len int, key *[8]uint32, counter *uint32)
+TEXT ·chaCha20_ctr32_vsx(SB),NOSPLIT,$64-40
+	MOVD out+0(FP), OUT
+	MOVD inp+8(FP), INP
+	MOVD len+16(FP), LEN
+	MOVD key+24(FP), KEY
+	MOVD counter+32(FP), CNT
+
+	// Addressing for constants
+	MOVD $consts<>+0x00(SB), CONSTBASE
+	MOVD $16, R8
+	MOVD $32, R9
+	MOVD $48, R10
+	MOVD $64, R11
+	SRD $6, LEN, BLOCKS
+	// for VPERMXOR
+	MOVD $consts<>+0xa0(SB), MASK
+	MOVD $16, R20
+	// V16
+	LXVW4X (CONSTBASE)(R0), VS48
+	ADD $80,CONSTBASE
+
+	// Load key into V17,V18
+	LXVW4X (KEY)(R0), VS49
+	LXVW4X (KEY)(R8), VS50
+
+	// Load CNT, NONCE into V19
+	LXVW4X (CNT)(R0), VS51
+
+	// Clear V27
+	VXOR V27, V27, V27
+
+	// V28
+	LXVW4X (CONSTBASE)(R11), VS60
+
+	// Load mask constants for VPERMXOR
+	LXVW4X (MASK)(R0), V20
+	LXVW4X (MASK)(R20), V21
+
+	// splat slot from V19 -> V26
+	VSPLTW $0, V19, V26
+
+	VSLDOI $4, V19, V27, V19
+	VSLDOI $12, V27, V19, V19
+
+	VADDUWM V26, V28, V26
+
+	MOVD $10, R14
+	MOVD R14, CTR
+	PCALIGN $16
+loop_outer_vsx:
+	// V0, V1, V2, V3
+	LXVW4X (R0)(CONSTBASE), VS32
+	LXVW4X (R8)(CONSTBASE), VS33
+	LXVW4X (R9)(CONSTBASE), VS34
+	LXVW4X (R10)(CONSTBASE), VS35
+
+	// splat values from V17, V18 into V4-V11
+	VSPLTW $0, V17, V4
+	VSPLTW $1, V17, V5
+	VSPLTW $2, V17, V6
+	VSPLTW $3, V17, V7
+	VSPLTW $0, V18, V8
+	VSPLTW $1, V18, V9
+	VSPLTW $2, V18, V10
+	VSPLTW $3, V18, V11
+
+	// VOR
+	VOR V26, V26, V12
+
+	// splat values from V19 -> V13, V14, V15
+	VSPLTW $1, V19, V13
+	VSPLTW $2, V19, V14
+	VSPLTW $3, V19, V15
+
+	// splat   const values
+	VSPLTISW $-16, V27
+	VSPLTISW $12, V28
+	VSPLTISW $8, V29
+	VSPLTISW $7, V30
+	PCALIGN $16
+loop_vsx:
+	VADDUWM V0, V4, V0
+	VADDUWM V1, V5, V1
+	VADDUWM V2, V6, V2
+	VADDUWM V3, V7, V3
+
+	VPERMXOR V12, V0, V21, V12
+	VPERMXOR V13, V1, V21, V13
+	VPERMXOR V14, V2, V21, V14
+	VPERMXOR V15, V3, V21, V15
+
+	VADDUWM V8, V12, V8
+	VADDUWM V9, V13, V9
+	VADDUWM V10, V14, V10
+	VADDUWM V11, V15, V11
+
+	VXOR V4, V8, V4
+	VXOR V5, V9, V5
+	VXOR V6, V10, V6
+	VXOR V7, V11, V7
+
+	VRLW V4, V28, V4
+	VRLW V5, V28, V5
+	VRLW V6, V28, V6
+	VRLW V7, V28, V7
+
+	VADDUWM V0, V4, V0
+	VADDUWM V1, V5, V1
+	VADDUWM V2, V6, V2
+	VADDUWM V3, V7, V3
+
+	VPERMXOR V12, V0, V20, V12
+	VPERMXOR V13, V1, V20, V13
+	VPERMXOR V14, V2, V20, V14
+	VPERMXOR V15, V3, V20, V15
+
+	VADDUWM V8, V12, V8
+	VADDUWM V9, V13, V9
+	VADDUWM V10, V14, V10
+	VADDUWM V11, V15, V11
+
+	VXOR V4, V8, V4
+	VXOR V5, V9, V5
+	VXOR V6, V10, V6
+	VXOR V7, V11, V7
+
+	VRLW V4, V30, V4
+	VRLW V5, V30, V5
+	VRLW V6, V30, V6
+	VRLW V7, V30, V7
+
+	VADDUWM V0, V5, V0
+	VADDUWM V1, V6, V1
+	VADDUWM V2, V7, V2
+	VADDUWM V3, V4, V3
+
+	VPERMXOR V15, V0, V21, V15
+	VPERMXOR V12, V1, V21, V12
+	VPERMXOR V13, V2, V21, V13
+	VPERMXOR V14, V3, V21, V14
+
+	VADDUWM V10, V15, V10
+	VADDUWM V11, V12, V11
+	VADDUWM V8, V13, V8
+	VADDUWM V9, V14, V9
+
+	VXOR V5, V10, V5
+	VXOR V6, V11, V6
+	VXOR V7, V8, V7
+	VXOR V4, V9, V4
+
+	VRLW V5, V28, V5
+	VRLW V6, V28, V6
+	VRLW V7, V28, V7
+	VRLW V4, V28, V4
+
+	VADDUWM V0, V5, V0
+	VADDUWM V1, V6, V1
+	VADDUWM V2, V7, V2
+	VADDUWM V3, V4, V3
+
+	VPERMXOR V15, V0, V20, V15
+	VPERMXOR V12, V1, V20, V12
+	VPERMXOR V13, V2, V20, V13
+	VPERMXOR V14, V3, V20, V14
+
+	VADDUWM V10, V15, V10
+	VADDUWM V11, V12, V11
+	VADDUWM V8, V13, V8
+	VADDUWM V9, V14, V9
+
+	VXOR V5, V10, V5
+	VXOR V6, V11, V6
+	VXOR V7, V8, V7
+	VXOR V4, V9, V4
+
+	VRLW V5, V30, V5
+	VRLW V6, V30, V6
+	VRLW V7, V30, V7
+	VRLW V4, V30, V4
+	BDNZ   loop_vsx
+
+	VADDUWM V12, V26, V12
+
+	VMRGEW V0, V1, V27
+	VMRGEW V2, V3, V28
+
+	VMRGOW V0, V1, V0
+	VMRGOW V2, V3, V2
+
+	VMRGEW V4, V5, V29
+	VMRGEW V6, V7, V30
+
+	XXPERMDI VS32, VS34, $0, VS33
+	XXPERMDI VS32, VS34, $3, VS35
+	XXPERMDI VS59, VS60, $0, VS32
+	XXPERMDI VS59, VS60, $3, VS34
+
+	VMRGOW V4, V5, V4
+	VMRGOW V6, V7, V6
+
+	VMRGEW V8, V9, V27
+	VMRGEW V10, V11, V28
+
+	XXPERMDI VS36, VS38, $0, VS37
+	XXPERMDI VS36, VS38, $3, VS39
+	XXPERMDI VS61, VS62, $0, VS36
+	XXPERMDI VS61, VS62, $3, VS38
+
+	VMRGOW V8, V9, V8
+	VMRGOW V10, V11, V10
+
+	VMRGEW V12, V13, V29
+	VMRGEW V14, V15, V30
+
+	XXPERMDI VS40, VS42, $0, VS41
+	XXPERMDI VS40, VS42, $3, VS43
+	XXPERMDI VS59, VS60, $0, VS40
+	XXPERMDI VS59, VS60, $3, VS42
+
+	VMRGOW V12, V13, V12
+	VMRGOW V14, V15, V14
+
+	VSPLTISW $4, V27
+	VADDUWM V26, V27, V26
+
+	XXPERMDI VS44, VS46, $0, VS45
+	XXPERMDI VS44, VS46, $3, VS47
+	XXPERMDI VS61, VS62, $0, VS44
+	XXPERMDI VS61, VS62, $3, VS46
+
+	VADDUWM V0, V16, V0
+	VADDUWM V4, V17, V4
+	VADDUWM V8, V18, V8
+	VADDUWM V12, V19, V12
+
+	CMPU LEN, $64
+	BLT tail_vsx
+
+	// Bottom of loop
+	LXVW4X (INP)(R0), VS59
+	LXVW4X (INP)(R8), VS60
+	LXVW4X (INP)(R9), VS61
+	LXVW4X (INP)(R10), VS62
+
+	VXOR V27, V0, V27
+	VXOR V28, V4, V28
+	VXOR V29, V8, V29
+	VXOR V30, V12, V30
+
+	STXVW4X VS59, (OUT)(R0)
+	STXVW4X VS60, (OUT)(R8)
+	ADD     $64, INP
+	STXVW4X VS61, (OUT)(R9)
+	ADD     $-64, LEN
+	STXVW4X VS62, (OUT)(R10)
+	ADD     $64, OUT
+	BEQ     done_vsx
+
+	VADDUWM V1, V16, V0
+	VADDUWM V5, V17, V4
+	VADDUWM V9, V18, V8
+	VADDUWM V13, V19, V12
+
+	CMPU  LEN, $64
+	BLT   tail_vsx
+
+	LXVW4X (INP)(R0), VS59
+	LXVW4X (INP)(R8), VS60
+	LXVW4X (INP)(R9), VS61
+	LXVW4X (INP)(R10), VS62
+	VXOR   V27, V0, V27
+
+	VXOR V28, V4, V28
+	VXOR V29, V8, V29
+	VXOR V30, V12, V30
+
+	STXVW4X VS59, (OUT)(R0)
+	STXVW4X VS60, (OUT)(R8)
+	ADD     $64, INP
+	STXVW4X VS61, (OUT)(R9)
+	ADD     $-64, LEN
+	STXVW4X VS62, (OUT)(V10)
+	ADD     $64, OUT
+	BEQ     done_vsx
+
+	VADDUWM V2, V16, V0
+	VADDUWM V6, V17, V4
+	VADDUWM V10, V18, V8
+	VADDUWM V14, V19, V12
+
+	CMPU LEN, $64
+	BLT  tail_vsx
+
+	LXVW4X (INP)(R0), VS59
+	LXVW4X (INP)(R8), VS60
+	LXVW4X (INP)(R9), VS61
+	LXVW4X (INP)(R10), VS62
+
+	VXOR V27, V0, V27
+	VXOR V28, V4, V28
+	VXOR V29, V8, V29
+	VXOR V30, V12, V30
+
+	STXVW4X VS59, (OUT)(R0)
+	STXVW4X VS60, (OUT)(R8)
+	ADD     $64, INP
+	STXVW4X VS61, (OUT)(R9)
+	ADD     $-64, LEN
+	STXVW4X VS62, (OUT)(R10)
+	ADD     $64, OUT
+	BEQ     done_vsx
+
+	VADDUWM V3, V16, V0
+	VADDUWM V7, V17, V4
+	VADDUWM V11, V18, V8
+	VADDUWM V15, V19, V12
+
+	CMPU  LEN, $64
+	BLT   tail_vsx
+
+	LXVW4X (INP)(R0), VS59
+	LXVW4X (INP)(R8), VS60
+	LXVW4X (INP)(R9), VS61
+	LXVW4X (INP)(R10), VS62
+
+	VXOR V27, V0, V27
+	VXOR V28, V4, V28
+	VXOR V29, V8, V29
+	VXOR V30, V12, V30
+
+	STXVW4X VS59, (OUT)(R0)
+	STXVW4X VS60, (OUT)(R8)
+	ADD     $64, INP
+	STXVW4X VS61, (OUT)(R9)
+	ADD     $-64, LEN
+	STXVW4X VS62, (OUT)(R10)
+	ADD     $64, OUT
+
+	MOVD $10, R14
+	MOVD R14, CTR
+	BNE  loop_outer_vsx
+
+done_vsx:
+	// Increment counter by number of 64 byte blocks
+	MOVD (CNT), R14
+	ADD  BLOCKS, R14
+	MOVD R14, (CNT)
+	RET
+
+tail_vsx:
+	ADD  $32, R1, R11
+	MOVD LEN, CTR
+
+	// Save values on stack to copy from
+	STXVW4X VS32, (R11)(R0)
+	STXVW4X VS36, (R11)(R8)
+	STXVW4X VS40, (R11)(R9)
+	STXVW4X VS44, (R11)(R10)
+	ADD $-1, R11, R12
+	ADD $-1, INP
+	ADD $-1, OUT
+	PCALIGN $16
+looptail_vsx:
+	// Copying the result to OUT
+	// in bytes.
+	MOVBZU 1(R12), KEY
+	MOVBZU 1(INP), TMP
+	XOR    KEY, TMP, KEY
+	MOVBU  KEY, 1(OUT)
+	BDNZ   looptail_vsx
+
+	// Clear the stack values
+	STXVW4X VS48, (R11)(R0)
+	STXVW4X VS48, (R11)(R8)
+	STXVW4X VS48, (R11)(R9)
+	STXVW4X VS48, (R11)(R10)
+	BR      done_vsx
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_s390x.go b/vendor/golang.org/x/crypto/chacha20/chacha_s390x.go
new file mode 100644
index 000000000..683ccfd1c
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_s390x.go
@@ -0,0 +1,27 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+package chacha20
+
+import "golang.org/x/sys/cpu"
+
+var haveAsm = cpu.S390X.HasVX
+
+const bufSize = 256
+
+// xorKeyStreamVX is an assembly implementation of XORKeyStream. It must only
+// be called when the vector facility is available. Implementation in asm_s390x.s.
+//
+//go:noescape
+func xorKeyStreamVX(dst, src []byte, key *[8]uint32, nonce *[3]uint32, counter *uint32)
+
+func (c *Cipher) xorKeyStreamBlocks(dst, src []byte) {
+	if cpu.S390X.HasVX {
+		xorKeyStreamVX(dst, src, &c.key, &c.nonce, &c.counter)
+	} else {
+		c.xorKeyStreamBlocksGeneric(dst, src)
+	}
+}
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_s390x.s b/vendor/golang.org/x/crypto/chacha20/chacha_s390x.s
new file mode 100644
index 000000000..1eda91a3d
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_s390x.s
@@ -0,0 +1,224 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+#include "go_asm.h"
+#include "textflag.h"
+
+// This is an implementation of the ChaCha20 encryption algorithm as
+// specified in RFC 7539. It uses vector instructions to compute
+// 4 keystream blocks in parallel (256 bytes) which are then XORed
+// with the bytes in the input slice.
+
+GLOBL ·constants<>(SB), RODATA|NOPTR, $32
+// BSWAP: swap bytes in each 4-byte element
+DATA ·constants<>+0x00(SB)/4, $0x03020100
+DATA ·constants<>+0x04(SB)/4, $0x07060504
+DATA ·constants<>+0x08(SB)/4, $0x0b0a0908
+DATA ·constants<>+0x0c(SB)/4, $0x0f0e0d0c
+// J0: [j0, j1, j2, j3]
+DATA ·constants<>+0x10(SB)/4, $0x61707865
+DATA ·constants<>+0x14(SB)/4, $0x3320646e
+DATA ·constants<>+0x18(SB)/4, $0x79622d32
+DATA ·constants<>+0x1c(SB)/4, $0x6b206574
+
+#define BSWAP V5
+#define J0    V6
+#define KEY0  V7
+#define KEY1  V8
+#define NONCE V9
+#define CTR   V10
+#define M0    V11
+#define M1    V12
+#define M2    V13
+#define M3    V14
+#define INC   V15
+#define X0    V16
+#define X1    V17
+#define X2    V18
+#define X3    V19
+#define X4    V20
+#define X5    V21
+#define X6    V22
+#define X7    V23
+#define X8    V24
+#define X9    V25
+#define X10   V26
+#define X11   V27
+#define X12   V28
+#define X13   V29
+#define X14   V30
+#define X15   V31
+
+#define NUM_ROUNDS 20
+
+#define ROUND4(a0, a1, a2, a3, b0, b1, b2, b3, c0, c1, c2, c3, d0, d1, d2, d3) \
+	VAF    a1, a0, a0  \
+	VAF    b1, b0, b0  \
+	VAF    c1, c0, c0  \
+	VAF    d1, d0, d0  \
+	VX     a0, a2, a2  \
+	VX     b0, b2, b2  \
+	VX     c0, c2, c2  \
+	VX     d0, d2, d2  \
+	VERLLF $16, a2, a2 \
+	VERLLF $16, b2, b2 \
+	VERLLF $16, c2, c2 \
+	VERLLF $16, d2, d2 \
+	VAF    a2, a3, a3  \
+	VAF    b2, b3, b3  \
+	VAF    c2, c3, c3  \
+	VAF    d2, d3, d3  \
+	VX     a3, a1, a1  \
+	VX     b3, b1, b1  \
+	VX     c3, c1, c1  \
+	VX     d3, d1, d1  \
+	VERLLF $12, a1, a1 \
+	VERLLF $12, b1, b1 \
+	VERLLF $12, c1, c1 \
+	VERLLF $12, d1, d1 \
+	VAF    a1, a0, a0  \
+	VAF    b1, b0, b0  \
+	VAF    c1, c0, c0  \
+	VAF    d1, d0, d0  \
+	VX     a0, a2, a2  \
+	VX     b0, b2, b2  \
+	VX     c0, c2, c2  \
+	VX     d0, d2, d2  \
+	VERLLF $8, a2, a2  \
+	VERLLF $8, b2, b2  \
+	VERLLF $8, c2, c2  \
+	VERLLF $8, d2, d2  \
+	VAF    a2, a3, a3  \
+	VAF    b2, b3, b3  \
+	VAF    c2, c3, c3  \
+	VAF    d2, d3, d3  \
+	VX     a3, a1, a1  \
+	VX     b3, b1, b1  \
+	VX     c3, c1, c1  \
+	VX     d3, d1, d1  \
+	VERLLF $7, a1, a1  \
+	VERLLF $7, b1, b1  \
+	VERLLF $7, c1, c1  \
+	VERLLF $7, d1, d1
+
+#define PERMUTE(mask, v0, v1, v2, v3) \
+	VPERM v0, v0, mask, v0 \
+	VPERM v1, v1, mask, v1 \
+	VPERM v2, v2, mask, v2 \
+	VPERM v3, v3, mask, v3
+
+#define ADDV(x, v0, v1, v2, v3) \
+	VAF x, v0, v0 \
+	VAF x, v1, v1 \
+	VAF x, v2, v2 \
+	VAF x, v3, v3
+
+#define XORV(off, dst, src, v0, v1, v2, v3) \
+	VLM  off(src), M0, M3          \
+	PERMUTE(BSWAP, v0, v1, v2, v3) \
+	VX   v0, M0, M0                \
+	VX   v1, M1, M1                \
+	VX   v2, M2, M2                \
+	VX   v3, M3, M3                \
+	VSTM M0, M3, off(dst)
+
+#define SHUFFLE(a, b, c, d, t, u, v, w) \
+	VMRHF a, c, t \ // t = {a[0], c[0], a[1], c[1]}
+	VMRHF b, d, u \ // u = {b[0], d[0], b[1], d[1]}
+	VMRLF a, c, v \ // v = {a[2], c[2], a[3], c[3]}
+	VMRLF b, d, w \ // w = {b[2], d[2], b[3], d[3]}
+	VMRHF t, u, a \ // a = {a[0], b[0], c[0], d[0]}
+	VMRLF t, u, b \ // b = {a[1], b[1], c[1], d[1]}
+	VMRHF v, w, c \ // c = {a[2], b[2], c[2], d[2]}
+	VMRLF v, w, d // d = {a[3], b[3], c[3], d[3]}
+
+// func xorKeyStreamVX(dst, src []byte, key *[8]uint32, nonce *[3]uint32, counter *uint32)
+TEXT ·xorKeyStreamVX(SB), NOSPLIT, $0
+	MOVD $·constants<>(SB), R1
+	MOVD dst+0(FP), R2         // R2=&dst[0]
+	LMG  src+24(FP), R3, R4    // R3=&src[0] R4=len(src)
+	MOVD key+48(FP), R5        // R5=key
+	MOVD nonce+56(FP), R6      // R6=nonce
+	MOVD counter+64(FP), R7    // R7=counter
+
+	// load BSWAP and J0
+	VLM (R1), BSWAP, J0
+
+	// setup
+	MOVD  $95, R0
+	VLM   (R5), KEY0, KEY1
+	VLL   R0, (R6), NONCE
+	VZERO M0
+	VLEIB $7, $32, M0
+	VSRLB M0, NONCE, NONCE
+
+	// initialize counter values
+	VLREPF (R7), CTR
+	VZERO  INC
+	VLEIF  $1, $1, INC
+	VLEIF  $2, $2, INC
+	VLEIF  $3, $3, INC
+	VAF    INC, CTR, CTR
+	VREPIF $4, INC
+
+chacha:
+	VREPF $0, J0, X0
+	VREPF $1, J0, X1
+	VREPF $2, J0, X2
+	VREPF $3, J0, X3
+	VREPF $0, KEY0, X4
+	VREPF $1, KEY0, X5
+	VREPF $2, KEY0, X6
+	VREPF $3, KEY0, X7
+	VREPF $0, KEY1, X8
+	VREPF $1, KEY1, X9
+	VREPF $2, KEY1, X10
+	VREPF $3, KEY1, X11
+	VLR   CTR, X12
+	VREPF $1, NONCE, X13
+	VREPF $2, NONCE, X14
+	VREPF $3, NONCE, X15
+
+	MOVD $(NUM_ROUNDS/2), R1
+
+loop:
+	ROUND4(X0, X4, X12,  X8, X1, X5, X13,  X9, X2, X6, X14, X10, X3, X7, X15, X11)
+	ROUND4(X0, X5, X15, X10, X1, X6, X12, X11, X2, X7, X13, X8,  X3, X4, X14, X9)
+
+	ADD $-1, R1
+	BNE loop
+
+	// decrement length
+	ADD $-256, R4
+
+	// rearrange vectors
+	SHUFFLE(X0, X1, X2, X3, M0, M1, M2, M3)
+	ADDV(J0, X0, X1, X2, X3)
+	SHUFFLE(X4, X5, X6, X7, M0, M1, M2, M3)
+	ADDV(KEY0, X4, X5, X6, X7)
+	SHUFFLE(X8, X9, X10, X11, M0, M1, M2, M3)
+	ADDV(KEY1, X8, X9, X10, X11)
+	VAF CTR, X12, X12
+	SHUFFLE(X12, X13, X14, X15, M0, M1, M2, M3)
+	ADDV(NONCE, X12, X13, X14, X15)
+
+	// increment counters
+	VAF INC, CTR, CTR
+
+	// xor keystream with plaintext
+	XORV(0*64, R2, R3, X0, X4,  X8, X12)
+	XORV(1*64, R2, R3, X1, X5,  X9, X13)
+	XORV(2*64, R2, R3, X2, X6, X10, X14)
+	XORV(3*64, R2, R3, X3, X7, X11, X15)
+
+	// increment pointers
+	MOVD $256(R2), R2
+	MOVD $256(R3), R3
+
+	CMPBNE  R4, $0, chacha
+
+	VSTEF $0, CTR, (R7)
+	RET
diff --git a/vendor/golang.org/x/crypto/chacha20/xor.go b/vendor/golang.org/x/crypto/chacha20/xor.go
new file mode 100644
index 000000000..c2d04851e
--- /dev/null
+++ b/vendor/golang.org/x/crypto/chacha20/xor.go
@@ -0,0 +1,42 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found src the LICENSE file.
+
+package chacha20
+
+import "runtime"
+
+// Platforms that have fast unaligned 32-bit little endian accesses.
+const unaligned = runtime.GOARCH == "386" ||
+	runtime.GOARCH == "amd64" ||
+	runtime.GOARCH == "arm64" ||
+	runtime.GOARCH == "ppc64le" ||
+	runtime.GOARCH == "s390x"
+
+// addXor reads a little endian uint32 from src, XORs it with (a + b) and
+// places the result in little endian byte order in dst.
+func addXor(dst, src []byte, a, b uint32) {
+	_, _ = src[3], dst[3] // bounds check elimination hint
+	if unaligned {
+		// The compiler should optimize this code into
+		// 32-bit unaligned little endian loads and stores.
+		// TODO: delete once the compiler does a reliably
+		// good job with the generic code below.
+		// See issue #25111 for more details.
+		v := uint32(src[0])
+		v |= uint32(src[1]) << 8
+		v |= uint32(src[2]) << 16
+		v |= uint32(src[3]) << 24
+		v ^= a + b
+		dst[0] = byte(v)
+		dst[1] = byte(v >> 8)
+		dst[2] = byte(v >> 16)
+		dst[3] = byte(v >> 24)
+	} else {
+		a += b
+		dst[0] = src[0] ^ byte(a)
+		dst[1] = src[1] ^ byte(a>>8)
+		dst[2] = src[2] ^ byte(a>>16)
+		dst[3] = src[3] ^ byte(a>>24)
+	}
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/curve25519.go b/vendor/golang.org/x/crypto/curve25519/curve25519.go
new file mode 100644
index 000000000..00f963ea2
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/curve25519.go
@@ -0,0 +1,59 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package curve25519 provides an implementation of the X25519 function, which
+// performs scalar multiplication on the elliptic curve known as Curve25519.
+// See RFC 7748.
+//
+// Starting in Go 1.20, this package is a wrapper for the X25519 implementation
+// in the crypto/ecdh package.
+package curve25519 // import "golang.org/x/crypto/curve25519"
+
+// ScalarMult sets dst to the product scalar * point.
+//
+// Deprecated: when provided a low-order point, ScalarMult will set dst to all
+// zeroes, irrespective of the scalar. Instead, use the X25519 function, which
+// will return an error.
+func ScalarMult(dst, scalar, point *[32]byte) {
+	scalarMult(dst, scalar, point)
+}
+
+// ScalarBaseMult sets dst to the product scalar * base where base is the
+// standard generator.
+//
+// It is recommended to use the X25519 function with Basepoint instead, as
+// copying into fixed size arrays can lead to unexpected bugs.
+func ScalarBaseMult(dst, scalar *[32]byte) {
+	scalarBaseMult(dst, scalar)
+}
+
+const (
+	// ScalarSize is the size of the scalar input to X25519.
+	ScalarSize = 32
+	// PointSize is the size of the point input to X25519.
+	PointSize = 32
+)
+
+// Basepoint is the canonical Curve25519 generator.
+var Basepoint []byte
+
+var basePoint = [32]byte{9}
+
+func init() { Basepoint = basePoint[:] }
+
+// X25519 returns the result of the scalar multiplication (scalar * point),
+// according to RFC 7748, Section 5. scalar, point and the return value are
+// slices of 32 bytes.
+//
+// scalar can be generated at random, for example with crypto/rand. point should
+// be either Basepoint or the output of another X25519 call.
+//
+// If point is Basepoint (but not if it's a different slice with the same
+// contents) a precomputed implementation might be used for performance.
+func X25519(scalar, point []byte) ([]byte, error) {
+	// Outline the body of function, to let the allocation be inlined in the
+	// caller, and possibly avoid escaping to the heap.
+	var dst [32]byte
+	return x25519(&dst, scalar, point)
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/curve25519_compat.go b/vendor/golang.org/x/crypto/curve25519/curve25519_compat.go
new file mode 100644
index 000000000..ba647e8d7
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/curve25519_compat.go
@@ -0,0 +1,105 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.20
+
+package curve25519
+
+import (
+	"crypto/subtle"
+	"errors"
+	"strconv"
+
+	"golang.org/x/crypto/curve25519/internal/field"
+)
+
+func scalarMult(dst, scalar, point *[32]byte) {
+	var e [32]byte
+
+	copy(e[:], scalar[:])
+	e[0] &= 248
+	e[31] &= 127
+	e[31] |= 64
+
+	var x1, x2, z2, x3, z3, tmp0, tmp1 field.Element
+	x1.SetBytes(point[:])
+	x2.One()
+	x3.Set(&x1)
+	z3.One()
+
+	swap := 0
+	for pos := 254; pos >= 0; pos-- {
+		b := e[pos/8] >> uint(pos&7)
+		b &= 1
+		swap ^= int(b)
+		x2.Swap(&x3, swap)
+		z2.Swap(&z3, swap)
+		swap = int(b)
+
+		tmp0.Subtract(&x3, &z3)
+		tmp1.Subtract(&x2, &z2)
+		x2.Add(&x2, &z2)
+		z2.Add(&x3, &z3)
+		z3.Multiply(&tmp0, &x2)
+		z2.Multiply(&z2, &tmp1)
+		tmp0.Square(&tmp1)
+		tmp1.Square(&x2)
+		x3.Add(&z3, &z2)
+		z2.Subtract(&z3, &z2)
+		x2.Multiply(&tmp1, &tmp0)
+		tmp1.Subtract(&tmp1, &tmp0)
+		z2.Square(&z2)
+
+		z3.Mult32(&tmp1, 121666)
+		x3.Square(&x3)
+		tmp0.Add(&tmp0, &z3)
+		z3.Multiply(&x1, &z2)
+		z2.Multiply(&tmp1, &tmp0)
+	}
+
+	x2.Swap(&x3, swap)
+	z2.Swap(&z3, swap)
+
+	z2.Invert(&z2)
+	x2.Multiply(&x2, &z2)
+	copy(dst[:], x2.Bytes())
+}
+
+func scalarBaseMult(dst, scalar *[32]byte) {
+	checkBasepoint()
+	scalarMult(dst, scalar, &basePoint)
+}
+
+func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
+	var in [32]byte
+	if l := len(scalar); l != 32 {
+		return nil, errors.New("bad scalar length: " + strconv.Itoa(l) + ", expected 32")
+	}
+	if l := len(point); l != 32 {
+		return nil, errors.New("bad point length: " + strconv.Itoa(l) + ", expected 32")
+	}
+	copy(in[:], scalar)
+	if &point[0] == &Basepoint[0] {
+		scalarBaseMult(dst, &in)
+	} else {
+		var base, zero [32]byte
+		copy(base[:], point)
+		scalarMult(dst, &in, &base)
+		if subtle.ConstantTimeCompare(dst[:], zero[:]) == 1 {
+			return nil, errors.New("bad input point: low order point")
+		}
+	}
+	return dst[:], nil
+}
+
+func checkBasepoint() {
+	if subtle.ConstantTimeCompare(Basepoint, []byte{
+		0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}) != 1 {
+		panic("curve25519: global Basepoint value was modified")
+	}
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/curve25519_go120.go b/vendor/golang.org/x/crypto/curve25519/curve25519_go120.go
new file mode 100644
index 000000000..627df4972
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/curve25519_go120.go
@@ -0,0 +1,46 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.20
+
+package curve25519
+
+import "crypto/ecdh"
+
+func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
+	curve := ecdh.X25519()
+	pub, err := curve.NewPublicKey(point)
+	if err != nil {
+		return nil, err
+	}
+	priv, err := curve.NewPrivateKey(scalar)
+	if err != nil {
+		return nil, err
+	}
+	out, err := priv.ECDH(pub)
+	if err != nil {
+		return nil, err
+	}
+	copy(dst[:], out)
+	return dst[:], nil
+}
+
+func scalarMult(dst, scalar, point *[32]byte) {
+	if _, err := x25519(dst, scalar[:], point[:]); err != nil {
+		// The only error condition for x25519 when the inputs are 32 bytes long
+		// is if the output would have been the all-zero value.
+		for i := range dst {
+			dst[i] = 0
+		}
+	}
+}
+
+func scalarBaseMult(dst, scalar *[32]byte) {
+	curve := ecdh.X25519()
+	priv, err := curve.NewPrivateKey(scalar[:])
+	if err != nil {
+		panic("curve25519: internal error: scalarBaseMult was not 32 bytes")
+	}
+	copy(dst[:], priv.PublicKey().Bytes())
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/README b/vendor/golang.org/x/crypto/curve25519/internal/field/README
new file mode 100644
index 000000000..e25bca7dc
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/README
@@ -0,0 +1,7 @@
+This package is kept in sync with crypto/ed25519/internal/edwards25519/field in
+the standard library.
+
+If there are any changes in the standard library that need to be synced to this
+package, run sync.sh. It will not overwrite any local changes made since the
+previous sync, so it's ok to land changes in this package first, and then sync
+to the standard library later.
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe.go b/vendor/golang.org/x/crypto/curve25519/internal/field/fe.go
new file mode 100644
index 000000000..ca841ad99
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe.go
@@ -0,0 +1,416 @@
+// Copyright (c) 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package field implements fast arithmetic modulo 2^255-19.
+package field
+
+import (
+	"crypto/subtle"
+	"encoding/binary"
+	"math/bits"
+)
+
+// Element represents an element of the field GF(2^255-19). Note that this
+// is not a cryptographically secure group, and should only be used to interact
+// with edwards25519.Point coordinates.
+//
+// This type works similarly to math/big.Int, and all arguments and receivers
+// are allowed to alias.
+//
+// The zero value is a valid zero element.
+type Element struct {
+	// An element t represents the integer
+	//     t.l0 + t.l1*2^51 + t.l2*2^102 + t.l3*2^153 + t.l4*2^204
+	//
+	// Between operations, all limbs are expected to be lower than 2^52.
+	l0 uint64
+	l1 uint64
+	l2 uint64
+	l3 uint64
+	l4 uint64
+}
+
+const maskLow51Bits uint64 = (1 << 51) - 1
+
+var feZero = &Element{0, 0, 0, 0, 0}
+
+// Zero sets v = 0, and returns v.
+func (v *Element) Zero() *Element {
+	*v = *feZero
+	return v
+}
+
+var feOne = &Element{1, 0, 0, 0, 0}
+
+// One sets v = 1, and returns v.
+func (v *Element) One() *Element {
+	*v = *feOne
+	return v
+}
+
+// reduce reduces v modulo 2^255 - 19 and returns it.
+func (v *Element) reduce() *Element {
+	v.carryPropagate()
+
+	// After the light reduction we now have a field element representation
+	// v < 2^255 + 2^13 * 19, but need v < 2^255 - 19.
+
+	// If v >= 2^255 - 19, then v + 19 >= 2^255, which would overflow 2^255 - 1,
+	// generating a carry. That is, c will be 0 if v < 2^255 - 19, and 1 otherwise.
+	c := (v.l0 + 19) >> 51
+	c = (v.l1 + c) >> 51
+	c = (v.l2 + c) >> 51
+	c = (v.l3 + c) >> 51
+	c = (v.l4 + c) >> 51
+
+	// If v < 2^255 - 19 and c = 0, this will be a no-op. Otherwise, it's
+	// effectively applying the reduction identity to the carry.
+	v.l0 += 19 * c
+
+	v.l1 += v.l0 >> 51
+	v.l0 = v.l0 & maskLow51Bits
+	v.l2 += v.l1 >> 51
+	v.l1 = v.l1 & maskLow51Bits
+	v.l3 += v.l2 >> 51
+	v.l2 = v.l2 & maskLow51Bits
+	v.l4 += v.l3 >> 51
+	v.l3 = v.l3 & maskLow51Bits
+	// no additional carry
+	v.l4 = v.l4 & maskLow51Bits
+
+	return v
+}
+
+// Add sets v = a + b, and returns v.
+func (v *Element) Add(a, b *Element) *Element {
+	v.l0 = a.l0 + b.l0
+	v.l1 = a.l1 + b.l1
+	v.l2 = a.l2 + b.l2
+	v.l3 = a.l3 + b.l3
+	v.l4 = a.l4 + b.l4
+	// Using the generic implementation here is actually faster than the
+	// assembly. Probably because the body of this function is so simple that
+	// the compiler can figure out better optimizations by inlining the carry
+	// propagation. TODO
+	return v.carryPropagateGeneric()
+}
+
+// Subtract sets v = a - b, and returns v.
+func (v *Element) Subtract(a, b *Element) *Element {
+	// We first add 2 * p, to guarantee the subtraction won't underflow, and
+	// then subtract b (which can be up to 2^255 + 2^13 * 19).
+	v.l0 = (a.l0 + 0xFFFFFFFFFFFDA) - b.l0
+	v.l1 = (a.l1 + 0xFFFFFFFFFFFFE) - b.l1
+	v.l2 = (a.l2 + 0xFFFFFFFFFFFFE) - b.l2
+	v.l3 = (a.l3 + 0xFFFFFFFFFFFFE) - b.l3
+	v.l4 = (a.l4 + 0xFFFFFFFFFFFFE) - b.l4
+	return v.carryPropagate()
+}
+
+// Negate sets v = -a, and returns v.
+func (v *Element) Negate(a *Element) *Element {
+	return v.Subtract(feZero, a)
+}
+
+// Invert sets v = 1/z mod p, and returns v.
+//
+// If z == 0, Invert returns v = 0.
+func (v *Element) Invert(z *Element) *Element {
+	// Inversion is implemented as exponentiation with exponent p − 2. It uses the
+	// same sequence of 255 squarings and 11 multiplications as [Curve25519].
+	var z2, z9, z11, z2_5_0, z2_10_0, z2_20_0, z2_50_0, z2_100_0, t Element
+
+	z2.Square(z)             // 2
+	t.Square(&z2)            // 4
+	t.Square(&t)             // 8
+	z9.Multiply(&t, z)       // 9
+	z11.Multiply(&z9, &z2)   // 11
+	t.Square(&z11)           // 22
+	z2_5_0.Multiply(&t, &z9) // 31 = 2^5 - 2^0
+
+	t.Square(&z2_5_0) // 2^6 - 2^1
+	for i := 0; i < 4; i++ {
+		t.Square(&t) // 2^10 - 2^5
+	}
+	z2_10_0.Multiply(&t, &z2_5_0) // 2^10 - 2^0
+
+	t.Square(&z2_10_0) // 2^11 - 2^1
+	for i := 0; i < 9; i++ {
+		t.Square(&t) // 2^20 - 2^10
+	}
+	z2_20_0.Multiply(&t, &z2_10_0) // 2^20 - 2^0
+
+	t.Square(&z2_20_0) // 2^21 - 2^1
+	for i := 0; i < 19; i++ {
+		t.Square(&t) // 2^40 - 2^20
+	}
+	t.Multiply(&t, &z2_20_0) // 2^40 - 2^0
+
+	t.Square(&t) // 2^41 - 2^1
+	for i := 0; i < 9; i++ {
+		t.Square(&t) // 2^50 - 2^10
+	}
+	z2_50_0.Multiply(&t, &z2_10_0) // 2^50 - 2^0
+
+	t.Square(&z2_50_0) // 2^51 - 2^1
+	for i := 0; i < 49; i++ {
+		t.Square(&t) // 2^100 - 2^50
+	}
+	z2_100_0.Multiply(&t, &z2_50_0) // 2^100 - 2^0
+
+	t.Square(&z2_100_0) // 2^101 - 2^1
+	for i := 0; i < 99; i++ {
+		t.Square(&t) // 2^200 - 2^100
+	}
+	t.Multiply(&t, &z2_100_0) // 2^200 - 2^0
+
+	t.Square(&t) // 2^201 - 2^1
+	for i := 0; i < 49; i++ {
+		t.Square(&t) // 2^250 - 2^50
+	}
+	t.Multiply(&t, &z2_50_0) // 2^250 - 2^0
+
+	t.Square(&t) // 2^251 - 2^1
+	t.Square(&t) // 2^252 - 2^2
+	t.Square(&t) // 2^253 - 2^3
+	t.Square(&t) // 2^254 - 2^4
+	t.Square(&t) // 2^255 - 2^5
+
+	return v.Multiply(&t, &z11) // 2^255 - 21
+}
+
+// Set sets v = a, and returns v.
+func (v *Element) Set(a *Element) *Element {
+	*v = *a
+	return v
+}
+
+// SetBytes sets v to x, which must be a 32-byte little-endian encoding.
+//
+// Consistent with RFC 7748, the most significant bit (the high bit of the
+// last byte) is ignored, and non-canonical values (2^255-19 through 2^255-1)
+// are accepted. Note that this is laxer than specified by RFC 8032.
+func (v *Element) SetBytes(x []byte) *Element {
+	if len(x) != 32 {
+		panic("edwards25519: invalid field element input size")
+	}
+
+	// Bits 0:51 (bytes 0:8, bits 0:64, shift 0, mask 51).
+	v.l0 = binary.LittleEndian.Uint64(x[0:8])
+	v.l0 &= maskLow51Bits
+	// Bits 51:102 (bytes 6:14, bits 48:112, shift 3, mask 51).
+	v.l1 = binary.LittleEndian.Uint64(x[6:14]) >> 3
+	v.l1 &= maskLow51Bits
+	// Bits 102:153 (bytes 12:20, bits 96:160, shift 6, mask 51).
+	v.l2 = binary.LittleEndian.Uint64(x[12:20]) >> 6
+	v.l2 &= maskLow51Bits
+	// Bits 153:204 (bytes 19:27, bits 152:216, shift 1, mask 51).
+	v.l3 = binary.LittleEndian.Uint64(x[19:27]) >> 1
+	v.l3 &= maskLow51Bits
+	// Bits 204:251 (bytes 24:32, bits 192:256, shift 12, mask 51).
+	// Note: not bytes 25:33, shift 4, to avoid overread.
+	v.l4 = binary.LittleEndian.Uint64(x[24:32]) >> 12
+	v.l4 &= maskLow51Bits
+
+	return v
+}
+
+// Bytes returns the canonical 32-byte little-endian encoding of v.
+func (v *Element) Bytes() []byte {
+	// This function is outlined to make the allocations inline in the caller
+	// rather than happen on the heap.
+	var out [32]byte
+	return v.bytes(&out)
+}
+
+func (v *Element) bytes(out *[32]byte) []byte {
+	t := *v
+	t.reduce()
+
+	var buf [8]byte
+	for i, l := range [5]uint64{t.l0, t.l1, t.l2, t.l3, t.l4} {
+		bitsOffset := i * 51
+		binary.LittleEndian.PutUint64(buf[:], l<<uint(bitsOffset%8))
+		for i, bb := range buf {
+			off := bitsOffset/8 + i
+			if off >= len(out) {
+				break
+			}
+			out[off] |= bb
+		}
+	}
+
+	return out[:]
+}
+
+// Equal returns 1 if v and u are equal, and 0 otherwise.
+func (v *Element) Equal(u *Element) int {
+	sa, sv := u.Bytes(), v.Bytes()
+	return subtle.ConstantTimeCompare(sa, sv)
+}
+
+// mask64Bits returns 0xffffffff if cond is 1, and 0 otherwise.
+func mask64Bits(cond int) uint64 { return ^(uint64(cond) - 1) }
+
+// Select sets v to a if cond == 1, and to b if cond == 0.
+func (v *Element) Select(a, b *Element, cond int) *Element {
+	m := mask64Bits(cond)
+	v.l0 = (m & a.l0) | (^m & b.l0)
+	v.l1 = (m & a.l1) | (^m & b.l1)
+	v.l2 = (m & a.l2) | (^m & b.l2)
+	v.l3 = (m & a.l3) | (^m & b.l3)
+	v.l4 = (m & a.l4) | (^m & b.l4)
+	return v
+}
+
+// Swap swaps v and u if cond == 1 or leaves them unchanged if cond == 0, and returns v.
+func (v *Element) Swap(u *Element, cond int) {
+	m := mask64Bits(cond)
+	t := m & (v.l0 ^ u.l0)
+	v.l0 ^= t
+	u.l0 ^= t
+	t = m & (v.l1 ^ u.l1)
+	v.l1 ^= t
+	u.l1 ^= t
+	t = m & (v.l2 ^ u.l2)
+	v.l2 ^= t
+	u.l2 ^= t
+	t = m & (v.l3 ^ u.l3)
+	v.l3 ^= t
+	u.l3 ^= t
+	t = m & (v.l4 ^ u.l4)
+	v.l4 ^= t
+	u.l4 ^= t
+}
+
+// IsNegative returns 1 if v is negative, and 0 otherwise.
+func (v *Element) IsNegative() int {
+	return int(v.Bytes()[0] & 1)
+}
+
+// Absolute sets v to |u|, and returns v.
+func (v *Element) Absolute(u *Element) *Element {
+	return v.Select(new(Element).Negate(u), u, u.IsNegative())
+}
+
+// Multiply sets v = x * y, and returns v.
+func (v *Element) Multiply(x, y *Element) *Element {
+	feMul(v, x, y)
+	return v
+}
+
+// Square sets v = x * x, and returns v.
+func (v *Element) Square(x *Element) *Element {
+	feSquare(v, x)
+	return v
+}
+
+// Mult32 sets v = x * y, and returns v.
+func (v *Element) Mult32(x *Element, y uint32) *Element {
+	x0lo, x0hi := mul51(x.l0, y)
+	x1lo, x1hi := mul51(x.l1, y)
+	x2lo, x2hi := mul51(x.l2, y)
+	x3lo, x3hi := mul51(x.l3, y)
+	x4lo, x4hi := mul51(x.l4, y)
+	v.l0 = x0lo + 19*x4hi // carried over per the reduction identity
+	v.l1 = x1lo + x0hi
+	v.l2 = x2lo + x1hi
+	v.l3 = x3lo + x2hi
+	v.l4 = x4lo + x3hi
+	// The hi portions are going to be only 32 bits, plus any previous excess,
+	// so we can skip the carry propagation.
+	return v
+}
+
+// mul51 returns lo + hi * 2⁵¹ = a * b.
+func mul51(a uint64, b uint32) (lo uint64, hi uint64) {
+	mh, ml := bits.Mul64(a, uint64(b))
+	lo = ml & maskLow51Bits
+	hi = (mh << 13) | (ml >> 51)
+	return
+}
+
+// Pow22523 set v = x^((p-5)/8), and returns v. (p-5)/8 is 2^252-3.
+func (v *Element) Pow22523(x *Element) *Element {
+	var t0, t1, t2 Element
+
+	t0.Square(x)             // x^2
+	t1.Square(&t0)           // x^4
+	t1.Square(&t1)           // x^8
+	t1.Multiply(x, &t1)      // x^9
+	t0.Multiply(&t0, &t1)    // x^11
+	t0.Square(&t0)           // x^22
+	t0.Multiply(&t1, &t0)    // x^31
+	t1.Square(&t0)           // x^62
+	for i := 1; i < 5; i++ { // x^992
+		t1.Square(&t1)
+	}
+	t0.Multiply(&t1, &t0)     // x^1023 -> 1023 = 2^10 - 1
+	t1.Square(&t0)            // 2^11 - 2
+	for i := 1; i < 10; i++ { // 2^20 - 2^10
+		t1.Square(&t1)
+	}
+	t1.Multiply(&t1, &t0)     // 2^20 - 1
+	t2.Square(&t1)            // 2^21 - 2
+	for i := 1; i < 20; i++ { // 2^40 - 2^20
+		t2.Square(&t2)
+	}
+	t1.Multiply(&t2, &t1)     // 2^40 - 1
+	t1.Square(&t1)            // 2^41 - 2
+	for i := 1; i < 10; i++ { // 2^50 - 2^10
+		t1.Square(&t1)
+	}
+	t0.Multiply(&t1, &t0)     // 2^50 - 1
+	t1.Square(&t0)            // 2^51 - 2
+	for i := 1; i < 50; i++ { // 2^100 - 2^50
+		t1.Square(&t1)
+	}
+	t1.Multiply(&t1, &t0)      // 2^100 - 1
+	t2.Square(&t1)             // 2^101 - 2
+	for i := 1; i < 100; i++ { // 2^200 - 2^100
+		t2.Square(&t2)
+	}
+	t1.Multiply(&t2, &t1)     // 2^200 - 1
+	t1.Square(&t1)            // 2^201 - 2
+	for i := 1; i < 50; i++ { // 2^250 - 2^50
+		t1.Square(&t1)
+	}
+	t0.Multiply(&t1, &t0)     // 2^250 - 1
+	t0.Square(&t0)            // 2^251 - 2
+	t0.Square(&t0)            // 2^252 - 4
+	return v.Multiply(&t0, x) // 2^252 - 3 -> x^(2^252-3)
+}
+
+// sqrtM1 is 2^((p-1)/4), which squared is equal to -1 by Euler's Criterion.
+var sqrtM1 = &Element{1718705420411056, 234908883556509,
+	2233514472574048, 2117202627021982, 765476049583133}
+
+// SqrtRatio sets r to the non-negative square root of the ratio of u and v.
+//
+// If u/v is square, SqrtRatio returns r and 1. If u/v is not square, SqrtRatio
+// sets r according to Section 4.3 of draft-irtf-cfrg-ristretto255-decaf448-00,
+// and returns r and 0.
+func (r *Element) SqrtRatio(u, v *Element) (rr *Element, wasSquare int) {
+	var a, b Element
+
+	// r = (u * v3) * (u * v7)^((p-5)/8)
+	v2 := a.Square(v)
+	uv3 := b.Multiply(u, b.Multiply(v2, v))
+	uv7 := a.Multiply(uv3, a.Square(v2))
+	r.Multiply(uv3, r.Pow22523(uv7))
+
+	check := a.Multiply(v, a.Square(r)) // check = v * r^2
+
+	uNeg := b.Negate(u)
+	correctSignSqrt := check.Equal(u)
+	flippedSignSqrt := check.Equal(uNeg)
+	flippedSignSqrtI := check.Equal(uNeg.Multiply(uNeg, sqrtM1))
+
+	rPrime := b.Multiply(r, sqrtM1) // r_prime = SQRT_M1 * r
+	// r = CT_SELECT(r_prime IF flipped_sign_sqrt | flipped_sign_sqrt_i ELSE r)
+	r.Select(rPrime, r, flippedSignSqrt|flippedSignSqrtI)
+
+	r.Absolute(r) // Choose the nonnegative square root.
+	return r, correctSignSqrt | flippedSignSqrt
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64.go b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64.go
new file mode 100644
index 000000000..70c541692
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64.go
@@ -0,0 +1,15 @@
+// Code generated by command: go run fe_amd64_asm.go -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field. DO NOT EDIT.
+
+//go:build amd64 && gc && !purego
+
+package field
+
+// feMul sets out = a * b. It works like feMulGeneric.
+//
+//go:noescape
+func feMul(out *Element, a *Element, b *Element)
+
+// feSquare sets out = a * a. It works like feSquareGeneric.
+//
+//go:noescape
+func feSquare(out *Element, a *Element)
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64.s b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64.s
new file mode 100644
index 000000000..60817acc4
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64.s
@@ -0,0 +1,378 @@
+// Code generated by command: go run fe_amd64_asm.go -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field. DO NOT EDIT.
+
+//go:build amd64 && gc && !purego
+
+#include "textflag.h"
+
+// func feMul(out *Element, a *Element, b *Element)
+TEXT ·feMul(SB), NOSPLIT, $0-24
+	MOVQ a+8(FP), CX
+	MOVQ b+16(FP), BX
+
+	// r0 = a0×b0
+	MOVQ (CX), AX
+	MULQ (BX)
+	MOVQ AX, DI
+	MOVQ DX, SI
+
+	// r0 += 19×a1×b4
+	MOVQ   8(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   32(BX)
+	ADDQ   AX, DI
+	ADCQ   DX, SI
+
+	// r0 += 19×a2×b3
+	MOVQ   16(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   24(BX)
+	ADDQ   AX, DI
+	ADCQ   DX, SI
+
+	// r0 += 19×a3×b2
+	MOVQ   24(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   16(BX)
+	ADDQ   AX, DI
+	ADCQ   DX, SI
+
+	// r0 += 19×a4×b1
+	MOVQ   32(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   8(BX)
+	ADDQ   AX, DI
+	ADCQ   DX, SI
+
+	// r1 = a0×b1
+	MOVQ (CX), AX
+	MULQ 8(BX)
+	MOVQ AX, R9
+	MOVQ DX, R8
+
+	// r1 += a1×b0
+	MOVQ 8(CX), AX
+	MULQ (BX)
+	ADDQ AX, R9
+	ADCQ DX, R8
+
+	// r1 += 19×a2×b4
+	MOVQ   16(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   32(BX)
+	ADDQ   AX, R9
+	ADCQ   DX, R8
+
+	// r1 += 19×a3×b3
+	MOVQ   24(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   24(BX)
+	ADDQ   AX, R9
+	ADCQ   DX, R8
+
+	// r1 += 19×a4×b2
+	MOVQ   32(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   16(BX)
+	ADDQ   AX, R9
+	ADCQ   DX, R8
+
+	// r2 = a0×b2
+	MOVQ (CX), AX
+	MULQ 16(BX)
+	MOVQ AX, R11
+	MOVQ DX, R10
+
+	// r2 += a1×b1
+	MOVQ 8(CX), AX
+	MULQ 8(BX)
+	ADDQ AX, R11
+	ADCQ DX, R10
+
+	// r2 += a2×b0
+	MOVQ 16(CX), AX
+	MULQ (BX)
+	ADDQ AX, R11
+	ADCQ DX, R10
+
+	// r2 += 19×a3×b4
+	MOVQ   24(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   32(BX)
+	ADDQ   AX, R11
+	ADCQ   DX, R10
+
+	// r2 += 19×a4×b3
+	MOVQ   32(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   24(BX)
+	ADDQ   AX, R11
+	ADCQ   DX, R10
+
+	// r3 = a0×b3
+	MOVQ (CX), AX
+	MULQ 24(BX)
+	MOVQ AX, R13
+	MOVQ DX, R12
+
+	// r3 += a1×b2
+	MOVQ 8(CX), AX
+	MULQ 16(BX)
+	ADDQ AX, R13
+	ADCQ DX, R12
+
+	// r3 += a2×b1
+	MOVQ 16(CX), AX
+	MULQ 8(BX)
+	ADDQ AX, R13
+	ADCQ DX, R12
+
+	// r3 += a3×b0
+	MOVQ 24(CX), AX
+	MULQ (BX)
+	ADDQ AX, R13
+	ADCQ DX, R12
+
+	// r3 += 19×a4×b4
+	MOVQ   32(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   32(BX)
+	ADDQ   AX, R13
+	ADCQ   DX, R12
+
+	// r4 = a0×b4
+	MOVQ (CX), AX
+	MULQ 32(BX)
+	MOVQ AX, R15
+	MOVQ DX, R14
+
+	// r4 += a1×b3
+	MOVQ 8(CX), AX
+	MULQ 24(BX)
+	ADDQ AX, R15
+	ADCQ DX, R14
+
+	// r4 += a2×b2
+	MOVQ 16(CX), AX
+	MULQ 16(BX)
+	ADDQ AX, R15
+	ADCQ DX, R14
+
+	// r4 += a3×b1
+	MOVQ 24(CX), AX
+	MULQ 8(BX)
+	ADDQ AX, R15
+	ADCQ DX, R14
+
+	// r4 += a4×b0
+	MOVQ 32(CX), AX
+	MULQ (BX)
+	ADDQ AX, R15
+	ADCQ DX, R14
+
+	// First reduction chain
+	MOVQ   $0x0007ffffffffffff, AX
+	SHLQ   $0x0d, DI, SI
+	SHLQ   $0x0d, R9, R8
+	SHLQ   $0x0d, R11, R10
+	SHLQ   $0x0d, R13, R12
+	SHLQ   $0x0d, R15, R14
+	ANDQ   AX, DI
+	IMUL3Q $0x13, R14, R14
+	ADDQ   R14, DI
+	ANDQ   AX, R9
+	ADDQ   SI, R9
+	ANDQ   AX, R11
+	ADDQ   R8, R11
+	ANDQ   AX, R13
+	ADDQ   R10, R13
+	ANDQ   AX, R15
+	ADDQ   R12, R15
+
+	// Second reduction chain (carryPropagate)
+	MOVQ   DI, SI
+	SHRQ   $0x33, SI
+	MOVQ   R9, R8
+	SHRQ   $0x33, R8
+	MOVQ   R11, R10
+	SHRQ   $0x33, R10
+	MOVQ   R13, R12
+	SHRQ   $0x33, R12
+	MOVQ   R15, R14
+	SHRQ   $0x33, R14
+	ANDQ   AX, DI
+	IMUL3Q $0x13, R14, R14
+	ADDQ   R14, DI
+	ANDQ   AX, R9
+	ADDQ   SI, R9
+	ANDQ   AX, R11
+	ADDQ   R8, R11
+	ANDQ   AX, R13
+	ADDQ   R10, R13
+	ANDQ   AX, R15
+	ADDQ   R12, R15
+
+	// Store output
+	MOVQ out+0(FP), AX
+	MOVQ DI, (AX)
+	MOVQ R9, 8(AX)
+	MOVQ R11, 16(AX)
+	MOVQ R13, 24(AX)
+	MOVQ R15, 32(AX)
+	RET
+
+// func feSquare(out *Element, a *Element)
+TEXT ·feSquare(SB), NOSPLIT, $0-16
+	MOVQ a+8(FP), CX
+
+	// r0 = l0×l0
+	MOVQ (CX), AX
+	MULQ (CX)
+	MOVQ AX, SI
+	MOVQ DX, BX
+
+	// r0 += 38×l1×l4
+	MOVQ   8(CX), AX
+	IMUL3Q $0x26, AX, AX
+	MULQ   32(CX)
+	ADDQ   AX, SI
+	ADCQ   DX, BX
+
+	// r0 += 38×l2×l3
+	MOVQ   16(CX), AX
+	IMUL3Q $0x26, AX, AX
+	MULQ   24(CX)
+	ADDQ   AX, SI
+	ADCQ   DX, BX
+
+	// r1 = 2×l0×l1
+	MOVQ (CX), AX
+	SHLQ $0x01, AX
+	MULQ 8(CX)
+	MOVQ AX, R8
+	MOVQ DX, DI
+
+	// r1 += 38×l2×l4
+	MOVQ   16(CX), AX
+	IMUL3Q $0x26, AX, AX
+	MULQ   32(CX)
+	ADDQ   AX, R8
+	ADCQ   DX, DI
+
+	// r1 += 19×l3×l3
+	MOVQ   24(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   24(CX)
+	ADDQ   AX, R8
+	ADCQ   DX, DI
+
+	// r2 = 2×l0×l2
+	MOVQ (CX), AX
+	SHLQ $0x01, AX
+	MULQ 16(CX)
+	MOVQ AX, R10
+	MOVQ DX, R9
+
+	// r2 += l1×l1
+	MOVQ 8(CX), AX
+	MULQ 8(CX)
+	ADDQ AX, R10
+	ADCQ DX, R9
+
+	// r2 += 38×l3×l4
+	MOVQ   24(CX), AX
+	IMUL3Q $0x26, AX, AX
+	MULQ   32(CX)
+	ADDQ   AX, R10
+	ADCQ   DX, R9
+
+	// r3 = 2×l0×l3
+	MOVQ (CX), AX
+	SHLQ $0x01, AX
+	MULQ 24(CX)
+	MOVQ AX, R12
+	MOVQ DX, R11
+
+	// r3 += 2×l1×l2
+	MOVQ   8(CX), AX
+	IMUL3Q $0x02, AX, AX
+	MULQ   16(CX)
+	ADDQ   AX, R12
+	ADCQ   DX, R11
+
+	// r3 += 19×l4×l4
+	MOVQ   32(CX), AX
+	IMUL3Q $0x13, AX, AX
+	MULQ   32(CX)
+	ADDQ   AX, R12
+	ADCQ   DX, R11
+
+	// r4 = 2×l0×l4
+	MOVQ (CX), AX
+	SHLQ $0x01, AX
+	MULQ 32(CX)
+	MOVQ AX, R14
+	MOVQ DX, R13
+
+	// r4 += 2×l1×l3
+	MOVQ   8(CX), AX
+	IMUL3Q $0x02, AX, AX
+	MULQ   24(CX)
+	ADDQ   AX, R14
+	ADCQ   DX, R13
+
+	// r4 += l2×l2
+	MOVQ 16(CX), AX
+	MULQ 16(CX)
+	ADDQ AX, R14
+	ADCQ DX, R13
+
+	// First reduction chain
+	MOVQ   $0x0007ffffffffffff, AX
+	SHLQ   $0x0d, SI, BX
+	SHLQ   $0x0d, R8, DI
+	SHLQ   $0x0d, R10, R9
+	SHLQ   $0x0d, R12, R11
+	SHLQ   $0x0d, R14, R13
+	ANDQ   AX, SI
+	IMUL3Q $0x13, R13, R13
+	ADDQ   R13, SI
+	ANDQ   AX, R8
+	ADDQ   BX, R8
+	ANDQ   AX, R10
+	ADDQ   DI, R10
+	ANDQ   AX, R12
+	ADDQ   R9, R12
+	ANDQ   AX, R14
+	ADDQ   R11, R14
+
+	// Second reduction chain (carryPropagate)
+	MOVQ   SI, BX
+	SHRQ   $0x33, BX
+	MOVQ   R8, DI
+	SHRQ   $0x33, DI
+	MOVQ   R10, R9
+	SHRQ   $0x33, R9
+	MOVQ   R12, R11
+	SHRQ   $0x33, R11
+	MOVQ   R14, R13
+	SHRQ   $0x33, R13
+	ANDQ   AX, SI
+	IMUL3Q $0x13, R13, R13
+	ADDQ   R13, SI
+	ANDQ   AX, R8
+	ADDQ   BX, R8
+	ANDQ   AX, R10
+	ADDQ   DI, R10
+	ANDQ   AX, R12
+	ADDQ   R9, R12
+	ANDQ   AX, R14
+	ADDQ   R11, R14
+
+	// Store output
+	MOVQ out+0(FP), AX
+	MOVQ SI, (AX)
+	MOVQ R8, 8(AX)
+	MOVQ R10, 16(AX)
+	MOVQ R12, 24(AX)
+	MOVQ R14, 32(AX)
+	RET
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64_noasm.go b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64_noasm.go
new file mode 100644
index 000000000..9da280d1d
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_amd64_noasm.go
@@ -0,0 +1,11 @@
+// Copyright (c) 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !amd64 || !gc || purego
+
+package field
+
+func feMul(v, x, y *Element) { feMulGeneric(v, x, y) }
+
+func feSquare(v, x *Element) { feSquareGeneric(v, x) }
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64.go b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64.go
new file mode 100644
index 000000000..075fe9b92
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64.go
@@ -0,0 +1,15 @@
+// Copyright (c) 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build arm64 && gc && !purego
+
+package field
+
+//go:noescape
+func carryPropagate(v *Element)
+
+func (v *Element) carryPropagate() *Element {
+	carryPropagate(v)
+	return v
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64.s b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64.s
new file mode 100644
index 000000000..3126a4341
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64.s
@@ -0,0 +1,42 @@
+// Copyright (c) 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build arm64 && gc && !purego
+
+#include "textflag.h"
+
+// carryPropagate works exactly like carryPropagateGeneric and uses the
+// same AND, ADD, and LSR+MADD instructions emitted by the compiler, but
+// avoids loading R0-R4 twice and uses LDP and STP.
+//
+// See https://golang.org/issues/43145 for the main compiler issue.
+//
+// func carryPropagate(v *Element)
+TEXT ·carryPropagate(SB),NOFRAME|NOSPLIT,$0-8
+	MOVD v+0(FP), R20
+
+	LDP 0(R20), (R0, R1)
+	LDP 16(R20), (R2, R3)
+	MOVD 32(R20), R4
+
+	AND $0x7ffffffffffff, R0, R10
+	AND $0x7ffffffffffff, R1, R11
+	AND $0x7ffffffffffff, R2, R12
+	AND $0x7ffffffffffff, R3, R13
+	AND $0x7ffffffffffff, R4, R14
+
+	ADD R0>>51, R11, R11
+	ADD R1>>51, R12, R12
+	ADD R2>>51, R13, R13
+	ADD R3>>51, R14, R14
+	// R4>>51 * 19 + R10 -> R10
+	LSR $51, R4, R21
+	MOVD $19, R22
+	MADD R22, R10, R21, R10
+
+	STP (R10, R11), 0(R20)
+	STP (R12, R13), 16(R20)
+	MOVD R14, 32(R20)
+
+	RET
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64_noasm.go b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64_noasm.go
new file mode 100644
index 000000000..fc029ac12
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_arm64_noasm.go
@@ -0,0 +1,11 @@
+// Copyright (c) 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !arm64 || !gc || purego
+
+package field
+
+func (v *Element) carryPropagate() *Element {
+	return v.carryPropagateGeneric()
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/fe_generic.go b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_generic.go
new file mode 100644
index 000000000..2671217da
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/fe_generic.go
@@ -0,0 +1,264 @@
+// Copyright (c) 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package field
+
+import "math/bits"
+
+// uint128 holds a 128-bit number as two 64-bit limbs, for use with the
+// bits.Mul64 and bits.Add64 intrinsics.
+type uint128 struct {
+	lo, hi uint64
+}
+
+// mul64 returns a * b.
+func mul64(a, b uint64) uint128 {
+	hi, lo := bits.Mul64(a, b)
+	return uint128{lo, hi}
+}
+
+// addMul64 returns v + a * b.
+func addMul64(v uint128, a, b uint64) uint128 {
+	hi, lo := bits.Mul64(a, b)
+	lo, c := bits.Add64(lo, v.lo, 0)
+	hi, _ = bits.Add64(hi, v.hi, c)
+	return uint128{lo, hi}
+}
+
+// shiftRightBy51 returns a >> 51. a is assumed to be at most 115 bits.
+func shiftRightBy51(a uint128) uint64 {
+	return (a.hi << (64 - 51)) | (a.lo >> 51)
+}
+
+func feMulGeneric(v, a, b *Element) {
+	a0 := a.l0
+	a1 := a.l1
+	a2 := a.l2
+	a3 := a.l3
+	a4 := a.l4
+
+	b0 := b.l0
+	b1 := b.l1
+	b2 := b.l2
+	b3 := b.l3
+	b4 := b.l4
+
+	// Limb multiplication works like pen-and-paper columnar multiplication, but
+	// with 51-bit limbs instead of digits.
+	//
+	//                          a4   a3   a2   a1   a0  x
+	//                          b4   b3   b2   b1   b0  =
+	//                         ------------------------
+	//                        a4b0 a3b0 a2b0 a1b0 a0b0  +
+	//                   a4b1 a3b1 a2b1 a1b1 a0b1       +
+	//              a4b2 a3b2 a2b2 a1b2 a0b2            +
+	//         a4b3 a3b3 a2b3 a1b3 a0b3                 +
+	//    a4b4 a3b4 a2b4 a1b4 a0b4                      =
+	//   ----------------------------------------------
+	//      r8   r7   r6   r5   r4   r3   r2   r1   r0
+	//
+	// We can then use the reduction identity (a * 2²⁵⁵ + b = a * 19 + b) to
+	// reduce the limbs that would overflow 255 bits. r5 * 2²⁵⁵ becomes 19 * r5,
+	// r6 * 2³⁰⁶ becomes 19 * r6 * 2⁵¹, etc.
+	//
+	// Reduction can be carried out simultaneously to multiplication. For
+	// example, we do not compute r5: whenever the result of a multiplication
+	// belongs to r5, like a1b4, we multiply it by 19 and add the result to r0.
+	//
+	//            a4b0    a3b0    a2b0    a1b0    a0b0  +
+	//            a3b1    a2b1    a1b1    a0b1 19×a4b1  +
+	//            a2b2    a1b2    a0b2 19×a4b2 19×a3b2  +
+	//            a1b3    a0b3 19×a4b3 19×a3b3 19×a2b3  +
+	//            a0b4 19×a4b4 19×a3b4 19×a2b4 19×a1b4  =
+	//           --------------------------------------
+	//              r4      r3      r2      r1      r0
+	//
+	// Finally we add up the columns into wide, overlapping limbs.
+
+	a1_19 := a1 * 19
+	a2_19 := a2 * 19
+	a3_19 := a3 * 19
+	a4_19 := a4 * 19
+
+	// r0 = a0×b0 + 19×(a1×b4 + a2×b3 + a3×b2 + a4×b1)
+	r0 := mul64(a0, b0)
+	r0 = addMul64(r0, a1_19, b4)
+	r0 = addMul64(r0, a2_19, b3)
+	r0 = addMul64(r0, a3_19, b2)
+	r0 = addMul64(r0, a4_19, b1)
+
+	// r1 = a0×b1 + a1×b0 + 19×(a2×b4 + a3×b3 + a4×b2)
+	r1 := mul64(a0, b1)
+	r1 = addMul64(r1, a1, b0)
+	r1 = addMul64(r1, a2_19, b4)
+	r1 = addMul64(r1, a3_19, b3)
+	r1 = addMul64(r1, a4_19, b2)
+
+	// r2 = a0×b2 + a1×b1 + a2×b0 + 19×(a3×b4 + a4×b3)
+	r2 := mul64(a0, b2)
+	r2 = addMul64(r2, a1, b1)
+	r2 = addMul64(r2, a2, b0)
+	r2 = addMul64(r2, a3_19, b4)
+	r2 = addMul64(r2, a4_19, b3)
+
+	// r3 = a0×b3 + a1×b2 + a2×b1 + a3×b0 + 19×a4×b4
+	r3 := mul64(a0, b3)
+	r3 = addMul64(r3, a1, b2)
+	r3 = addMul64(r3, a2, b1)
+	r3 = addMul64(r3, a3, b0)
+	r3 = addMul64(r3, a4_19, b4)
+
+	// r4 = a0×b4 + a1×b3 + a2×b2 + a3×b1 + a4×b0
+	r4 := mul64(a0, b4)
+	r4 = addMul64(r4, a1, b3)
+	r4 = addMul64(r4, a2, b2)
+	r4 = addMul64(r4, a3, b1)
+	r4 = addMul64(r4, a4, b0)
+
+	// After the multiplication, we need to reduce (carry) the five coefficients
+	// to obtain a result with limbs that are at most slightly larger than 2⁵¹,
+	// to respect the Element invariant.
+	//
+	// Overall, the reduction works the same as carryPropagate, except with
+	// wider inputs: we take the carry for each coefficient by shifting it right
+	// by 51, and add it to the limb above it. The top carry is multiplied by 19
+	// according to the reduction identity and added to the lowest limb.
+	//
+	// The largest coefficient (r0) will be at most 111 bits, which guarantees
+	// that all carries are at most 111 - 51 = 60 bits, which fits in a uint64.
+	//
+	//     r0 = a0×b0 + 19×(a1×b4 + a2×b3 + a3×b2 + a4×b1)
+	//     r0 < 2⁵²×2⁵² + 19×(2⁵²×2⁵² + 2⁵²×2⁵² + 2⁵²×2⁵² + 2⁵²×2⁵²)
+	//     r0 < (1 + 19 × 4) × 2⁵² × 2⁵²
+	//     r0 < 2⁷ × 2⁵² × 2⁵²
+	//     r0 < 2¹¹¹
+	//
+	// Moreover, the top coefficient (r4) is at most 107 bits, so c4 is at most
+	// 56 bits, and c4 * 19 is at most 61 bits, which again fits in a uint64 and
+	// allows us to easily apply the reduction identity.
+	//
+	//     r4 = a0×b4 + a1×b3 + a2×b2 + a3×b1 + a4×b0
+	//     r4 < 5 × 2⁵² × 2⁵²
+	//     r4 < 2¹⁰⁷
+	//
+
+	c0 := shiftRightBy51(r0)
+	c1 := shiftRightBy51(r1)
+	c2 := shiftRightBy51(r2)
+	c3 := shiftRightBy51(r3)
+	c4 := shiftRightBy51(r4)
+
+	rr0 := r0.lo&maskLow51Bits + c4*19
+	rr1 := r1.lo&maskLow51Bits + c0
+	rr2 := r2.lo&maskLow51Bits + c1
+	rr3 := r3.lo&maskLow51Bits + c2
+	rr4 := r4.lo&maskLow51Bits + c3
+
+	// Now all coefficients fit into 64-bit registers but are still too large to
+	// be passed around as a Element. We therefore do one last carry chain,
+	// where the carries will be small enough to fit in the wiggle room above 2⁵¹.
+	*v = Element{rr0, rr1, rr2, rr3, rr4}
+	v.carryPropagate()
+}
+
+func feSquareGeneric(v, a *Element) {
+	l0 := a.l0
+	l1 := a.l1
+	l2 := a.l2
+	l3 := a.l3
+	l4 := a.l4
+
+	// Squaring works precisely like multiplication above, but thanks to its
+	// symmetry we get to group a few terms together.
+	//
+	//                          l4   l3   l2   l1   l0  x
+	//                          l4   l3   l2   l1   l0  =
+	//                         ------------------------
+	//                        l4l0 l3l0 l2l0 l1l0 l0l0  +
+	//                   l4l1 l3l1 l2l1 l1l1 l0l1       +
+	//              l4l2 l3l2 l2l2 l1l2 l0l2            +
+	//         l4l3 l3l3 l2l3 l1l3 l0l3                 +
+	//    l4l4 l3l4 l2l4 l1l4 l0l4                      =
+	//   ----------------------------------------------
+	//      r8   r7   r6   r5   r4   r3   r2   r1   r0
+	//
+	//            l4l0    l3l0    l2l0    l1l0    l0l0  +
+	//            l3l1    l2l1    l1l1    l0l1 19×l4l1  +
+	//            l2l2    l1l2    l0l2 19×l4l2 19×l3l2  +
+	//            l1l3    l0l3 19×l4l3 19×l3l3 19×l2l3  +
+	//            l0l4 19×l4l4 19×l3l4 19×l2l4 19×l1l4  =
+	//           --------------------------------------
+	//              r4      r3      r2      r1      r0
+	//
+	// With precomputed 2×, 19×, and 2×19× terms, we can compute each limb with
+	// only three Mul64 and four Add64, instead of five and eight.
+
+	l0_2 := l0 * 2
+	l1_2 := l1 * 2
+
+	l1_38 := l1 * 38
+	l2_38 := l2 * 38
+	l3_38 := l3 * 38
+
+	l3_19 := l3 * 19
+	l4_19 := l4 * 19
+
+	// r0 = l0×l0 + 19×(l1×l4 + l2×l3 + l3×l2 + l4×l1) = l0×l0 + 19×2×(l1×l4 + l2×l3)
+	r0 := mul64(l0, l0)
+	r0 = addMul64(r0, l1_38, l4)
+	r0 = addMul64(r0, l2_38, l3)
+
+	// r1 = l0×l1 + l1×l0 + 19×(l2×l4 + l3×l3 + l4×l2) = 2×l0×l1 + 19×2×l2×l4 + 19×l3×l3
+	r1 := mul64(l0_2, l1)
+	r1 = addMul64(r1, l2_38, l4)
+	r1 = addMul64(r1, l3_19, l3)
+
+	// r2 = l0×l2 + l1×l1 + l2×l0 + 19×(l3×l4 + l4×l3) = 2×l0×l2 + l1×l1 + 19×2×l3×l4
+	r2 := mul64(l0_2, l2)
+	r2 = addMul64(r2, l1, l1)
+	r2 = addMul64(r2, l3_38, l4)
+
+	// r3 = l0×l3 + l1×l2 + l2×l1 + l3×l0 + 19×l4×l4 = 2×l0×l3 + 2×l1×l2 + 19×l4×l4
+	r3 := mul64(l0_2, l3)
+	r3 = addMul64(r3, l1_2, l2)
+	r3 = addMul64(r3, l4_19, l4)
+
+	// r4 = l0×l4 + l1×l3 + l2×l2 + l3×l1 + l4×l0 = 2×l0×l4 + 2×l1×l3 + l2×l2
+	r4 := mul64(l0_2, l4)
+	r4 = addMul64(r4, l1_2, l3)
+	r4 = addMul64(r4, l2, l2)
+
+	c0 := shiftRightBy51(r0)
+	c1 := shiftRightBy51(r1)
+	c2 := shiftRightBy51(r2)
+	c3 := shiftRightBy51(r3)
+	c4 := shiftRightBy51(r4)
+
+	rr0 := r0.lo&maskLow51Bits + c4*19
+	rr1 := r1.lo&maskLow51Bits + c0
+	rr2 := r2.lo&maskLow51Bits + c1
+	rr3 := r3.lo&maskLow51Bits + c2
+	rr4 := r4.lo&maskLow51Bits + c3
+
+	*v = Element{rr0, rr1, rr2, rr3, rr4}
+	v.carryPropagate()
+}
+
+// carryPropagateGeneric brings the limbs below 52 bits by applying the reduction
+// identity (a * 2²⁵⁵ + b = a * 19 + b) to the l4 carry. TODO inline
+func (v *Element) carryPropagateGeneric() *Element {
+	c0 := v.l0 >> 51
+	c1 := v.l1 >> 51
+	c2 := v.l2 >> 51
+	c3 := v.l3 >> 51
+	c4 := v.l4 >> 51
+
+	v.l0 = v.l0&maskLow51Bits + c4*19
+	v.l1 = v.l1&maskLow51Bits + c0
+	v.l2 = v.l2&maskLow51Bits + c1
+	v.l3 = v.l3&maskLow51Bits + c2
+	v.l4 = v.l4&maskLow51Bits + c3
+
+	return v
+}
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/sync.checkpoint b/vendor/golang.org/x/crypto/curve25519/internal/field/sync.checkpoint
new file mode 100644
index 000000000..e3685f95c
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/sync.checkpoint
@@ -0,0 +1 @@
+b0c49ae9f59d233526f8934262c5bbbe14d4358d
diff --git a/vendor/golang.org/x/crypto/curve25519/internal/field/sync.sh b/vendor/golang.org/x/crypto/curve25519/internal/field/sync.sh
new file mode 100644
index 000000000..1ba22a8b4
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/internal/field/sync.sh
@@ -0,0 +1,19 @@
+#! /bin/bash
+set -euo pipefail
+
+cd "$(git rev-parse --show-toplevel)"
+
+STD_PATH=src/crypto/ed25519/internal/edwards25519/field
+LOCAL_PATH=curve25519/internal/field
+LAST_SYNC_REF=$(cat $LOCAL_PATH/sync.checkpoint)
+
+git fetch https://go.googlesource.com/go master
+
+if git diff --quiet $LAST_SYNC_REF:$STD_PATH FETCH_HEAD:$STD_PATH; then
+    echo "No changes."
+else
+    NEW_REF=$(git rev-parse FETCH_HEAD | tee $LOCAL_PATH/sync.checkpoint)
+    echo "Applying changes from $LAST_SYNC_REF to $NEW_REF..."
+    git diff $LAST_SYNC_REF:$STD_PATH FETCH_HEAD:$STD_PATH | \
+        git apply -3 --directory=$LOCAL_PATH
+fi
diff --git a/vendor/golang.org/x/crypto/internal/alias/alias.go b/vendor/golang.org/x/crypto/internal/alias/alias.go
new file mode 100644
index 000000000..551ff0c35
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/alias/alias.go
@@ -0,0 +1,31 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !purego
+
+// Package alias implements memory aliasing tests.
+package alias
+
+import "unsafe"
+
+// AnyOverlap reports whether x and y share memory at any (not necessarily
+// corresponding) index. The memory beyond the slice length is ignored.
+func AnyOverlap(x, y []byte) bool {
+	return len(x) > 0 && len(y) > 0 &&
+		uintptr(unsafe.Pointer(&x[0])) <= uintptr(unsafe.Pointer(&y[len(y)-1])) &&
+		uintptr(unsafe.Pointer(&y[0])) <= uintptr(unsafe.Pointer(&x[len(x)-1]))
+}
+
+// InexactOverlap reports whether x and y share memory at any non-corresponding
+// index. The memory beyond the slice length is ignored. Note that x and y can
+// have different lengths and still not have any inexact overlap.
+//
+// InexactOverlap can be used to implement the requirements of the crypto/cipher
+// AEAD, Block, BlockMode and Stream interfaces.
+func InexactOverlap(x, y []byte) bool {
+	if len(x) == 0 || len(y) == 0 || &x[0] == &y[0] {
+		return false
+	}
+	return AnyOverlap(x, y)
+}
diff --git a/vendor/golang.org/x/crypto/internal/alias/alias_purego.go b/vendor/golang.org/x/crypto/internal/alias/alias_purego.go
new file mode 100644
index 000000000..6fe61b5c6
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/alias/alias_purego.go
@@ -0,0 +1,34 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build purego
+
+// Package alias implements memory aliasing tests.
+package alias
+
+// This is the Google App Engine standard variant based on reflect
+// because the unsafe package and cgo are disallowed.
+
+import "reflect"
+
+// AnyOverlap reports whether x and y share memory at any (not necessarily
+// corresponding) index. The memory beyond the slice length is ignored.
+func AnyOverlap(x, y []byte) bool {
+	return len(x) > 0 && len(y) > 0 &&
+		reflect.ValueOf(&x[0]).Pointer() <= reflect.ValueOf(&y[len(y)-1]).Pointer() &&
+		reflect.ValueOf(&y[0]).Pointer() <= reflect.ValueOf(&x[len(x)-1]).Pointer()
+}
+
+// InexactOverlap reports whether x and y share memory at any non-corresponding
+// index. The memory beyond the slice length is ignored. Note that x and y can
+// have different lengths and still not have any inexact overlap.
+//
+// InexactOverlap can be used to implement the requirements of the crypto/cipher
+// AEAD, Block, BlockMode and Stream interfaces.
+func InexactOverlap(x, y []byte) bool {
+	if len(x) == 0 || len(y) == 0 || &x[0] == &y[0] {
+		return false
+	}
+	return AnyOverlap(x, y)
+}
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/mac_noasm.go b/vendor/golang.org/x/crypto/internal/poly1305/mac_noasm.go
new file mode 100644
index 000000000..333da285b
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/mac_noasm.go
@@ -0,0 +1,9 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (!amd64 && !ppc64le && !s390x) || !gc || purego
+
+package poly1305
+
+type mac struct{ macGeneric }
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/poly1305.go b/vendor/golang.org/x/crypto/internal/poly1305/poly1305.go
new file mode 100644
index 000000000..4aaea810a
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/poly1305.go
@@ -0,0 +1,99 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package poly1305 implements Poly1305 one-time message authentication code as
+// specified in https://cr.yp.to/mac/poly1305-20050329.pdf.
+//
+// Poly1305 is a fast, one-time authentication function. It is infeasible for an
+// attacker to generate an authenticator for a message without the key. However, a
+// key must only be used for a single message. Authenticating two different
+// messages with the same key allows an attacker to forge authenticators for other
+// messages with the same key.
+//
+// Poly1305 was originally coupled with AES in order to make Poly1305-AES. AES was
+// used with a fixed key in order to generate one-time keys from an nonce.
+// However, in this package AES isn't used and the one-time key is specified
+// directly.
+package poly1305
+
+import "crypto/subtle"
+
+// TagSize is the size, in bytes, of a poly1305 authenticator.
+const TagSize = 16
+
+// Sum generates an authenticator for msg using a one-time key and puts the
+// 16-byte result into out. Authenticating two different messages with the same
+// key allows an attacker to forge messages at will.
+func Sum(out *[16]byte, m []byte, key *[32]byte) {
+	h := New(key)
+	h.Write(m)
+	h.Sum(out[:0])
+}
+
+// Verify returns true if mac is a valid authenticator for m with the given key.
+func Verify(mac *[16]byte, m []byte, key *[32]byte) bool {
+	var tmp [16]byte
+	Sum(&tmp, m, key)
+	return subtle.ConstantTimeCompare(tmp[:], mac[:]) == 1
+}
+
+// New returns a new MAC computing an authentication
+// tag of all data written to it with the given key.
+// This allows writing the message progressively instead
+// of passing it as a single slice. Common users should use
+// the Sum function instead.
+//
+// The key must be unique for each message, as authenticating
+// two different messages with the same key allows an attacker
+// to forge messages at will.
+func New(key *[32]byte) *MAC {
+	m := &MAC{}
+	initialize(key, &m.macState)
+	return m
+}
+
+// MAC is an io.Writer computing an authentication tag
+// of the data written to it.
+//
+// MAC cannot be used like common hash.Hash implementations,
+// because using a poly1305 key twice breaks its security.
+// Therefore writing data to a running MAC after calling
+// Sum or Verify causes it to panic.
+type MAC struct {
+	mac // platform-dependent implementation
+
+	finalized bool
+}
+
+// Size returns the number of bytes Sum will return.
+func (h *MAC) Size() int { return TagSize }
+
+// Write adds more data to the running message authentication code.
+// It never returns an error.
+//
+// It must not be called after the first call of Sum or Verify.
+func (h *MAC) Write(p []byte) (n int, err error) {
+	if h.finalized {
+		panic("poly1305: write to MAC after Sum or Verify")
+	}
+	return h.mac.Write(p)
+}
+
+// Sum computes the authenticator of all data written to the
+// message authentication code.
+func (h *MAC) Sum(b []byte) []byte {
+	var mac [TagSize]byte
+	h.mac.Sum(&mac)
+	h.finalized = true
+	return append(b, mac[:]...)
+}
+
+// Verify returns whether the authenticator of all data written to
+// the message authentication code matches the expected value.
+func (h *MAC) Verify(expected []byte) bool {
+	var mac [TagSize]byte
+	h.mac.Sum(&mac)
+	h.finalized = true
+	return subtle.ConstantTimeCompare(expected, mac[:]) == 1
+}
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.go b/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.go
new file mode 100644
index 000000000..164cd47d3
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.go
@@ -0,0 +1,47 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+package poly1305
+
+//go:noescape
+func update(state *macState, msg []byte)
+
+// mac is a wrapper for macGeneric that redirects calls that would have gone to
+// updateGeneric to update.
+//
+// Its Write and Sum methods are otherwise identical to the macGeneric ones, but
+// using function pointers would carry a major performance cost.
+type mac struct{ macGeneric }
+
+func (h *mac) Write(p []byte) (int, error) {
+	nn := len(p)
+	if h.offset > 0 {
+		n := copy(h.buffer[h.offset:], p)
+		if h.offset+n < TagSize {
+			h.offset += n
+			return nn, nil
+		}
+		p = p[n:]
+		h.offset = 0
+		update(&h.macState, h.buffer[:])
+	}
+	if n := len(p) - (len(p) % TagSize); n > 0 {
+		update(&h.macState, p[:n])
+		p = p[n:]
+	}
+	if len(p) > 0 {
+		h.offset += copy(h.buffer[h.offset:], p)
+	}
+	return nn, nil
+}
+
+func (h *mac) Sum(out *[16]byte) {
+	state := h.macState
+	if h.offset > 0 {
+		update(&state, h.buffer[:h.offset])
+	}
+	finalize(out, &state.h, &state.s)
+}
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.s b/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.s
new file mode 100644
index 000000000..e0d3c6475
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.s
@@ -0,0 +1,108 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+#include "textflag.h"
+
+#define POLY1305_ADD(msg, h0, h1, h2) \
+	ADDQ 0(msg), h0;  \
+	ADCQ 8(msg), h1;  \
+	ADCQ $1, h2;      \
+	LEAQ 16(msg), msg
+
+#define POLY1305_MUL(h0, h1, h2, r0, r1, t0, t1, t2, t3) \
+	MOVQ  r0, AX;                  \
+	MULQ  h0;                      \
+	MOVQ  AX, t0;                  \
+	MOVQ  DX, t1;                  \
+	MOVQ  r0, AX;                  \
+	MULQ  h1;                      \
+	ADDQ  AX, t1;                  \
+	ADCQ  $0, DX;                  \
+	MOVQ  r0, t2;                  \
+	IMULQ h2, t2;                  \
+	ADDQ  DX, t2;                  \
+	                               \
+	MOVQ  r1, AX;                  \
+	MULQ  h0;                      \
+	ADDQ  AX, t1;                  \
+	ADCQ  $0, DX;                  \
+	MOVQ  DX, h0;                  \
+	MOVQ  r1, t3;                  \
+	IMULQ h2, t3;                  \
+	MOVQ  r1, AX;                  \
+	MULQ  h1;                      \
+	ADDQ  AX, t2;                  \
+	ADCQ  DX, t3;                  \
+	ADDQ  h0, t2;                  \
+	ADCQ  $0, t3;                  \
+	                               \
+	MOVQ  t0, h0;                  \
+	MOVQ  t1, h1;                  \
+	MOVQ  t2, h2;                  \
+	ANDQ  $3, h2;                  \
+	MOVQ  t2, t0;                  \
+	ANDQ  $0xFFFFFFFFFFFFFFFC, t0; \
+	ADDQ  t0, h0;                  \
+	ADCQ  t3, h1;                  \
+	ADCQ  $0, h2;                  \
+	SHRQ  $2, t3, t2;              \
+	SHRQ  $2, t3;                  \
+	ADDQ  t2, h0;                  \
+	ADCQ  t3, h1;                  \
+	ADCQ  $0, h2
+
+// func update(state *[7]uint64, msg []byte)
+TEXT ·update(SB), $0-32
+	MOVQ state+0(FP), DI
+	MOVQ msg_base+8(FP), SI
+	MOVQ msg_len+16(FP), R15
+
+	MOVQ 0(DI), R8   // h0
+	MOVQ 8(DI), R9   // h1
+	MOVQ 16(DI), R10 // h2
+	MOVQ 24(DI), R11 // r0
+	MOVQ 32(DI), R12 // r1
+
+	CMPQ R15, $16
+	JB   bytes_between_0_and_15
+
+loop:
+	POLY1305_ADD(SI, R8, R9, R10)
+
+multiply:
+	POLY1305_MUL(R8, R9, R10, R11, R12, BX, CX, R13, R14)
+	SUBQ $16, R15
+	CMPQ R15, $16
+	JAE  loop
+
+bytes_between_0_and_15:
+	TESTQ R15, R15
+	JZ    done
+	MOVQ  $1, BX
+	XORQ  CX, CX
+	XORQ  R13, R13
+	ADDQ  R15, SI
+
+flush_buffer:
+	SHLQ $8, BX, CX
+	SHLQ $8, BX
+	MOVB -1(SI), R13
+	XORQ R13, BX
+	DECQ SI
+	DECQ R15
+	JNZ  flush_buffer
+
+	ADDQ BX, R8
+	ADCQ CX, R9
+	ADCQ $0, R10
+	MOVQ $16, R15
+	JMP  multiply
+
+done:
+	MOVQ R8, 0(DI)
+	MOVQ R9, 8(DI)
+	MOVQ R10, 16(DI)
+	RET
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_generic.go b/vendor/golang.org/x/crypto/internal/poly1305/sum_generic.go
new file mode 100644
index 000000000..ec2202bd7
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_generic.go
@@ -0,0 +1,312 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file provides the generic implementation of Sum and MAC. Other files
+// might provide optimized assembly implementations of some of this code.
+
+package poly1305
+
+import (
+	"encoding/binary"
+	"math/bits"
+)
+
+// Poly1305 [RFC 7539] is a relatively simple algorithm: the authentication tag
+// for a 64 bytes message is approximately
+//
+//     s + m[0:16] * r⁴ + m[16:32] * r³ + m[32:48] * r² + m[48:64] * r  mod  2¹³⁰ - 5
+//
+// for some secret r and s. It can be computed sequentially like
+//
+//     for len(msg) > 0:
+//         h += read(msg, 16)
+//         h *= r
+//         h %= 2¹³⁰ - 5
+//     return h + s
+//
+// All the complexity is about doing performant constant-time math on numbers
+// larger than any available numeric type.
+
+func sumGeneric(out *[TagSize]byte, msg []byte, key *[32]byte) {
+	h := newMACGeneric(key)
+	h.Write(msg)
+	h.Sum(out)
+}
+
+func newMACGeneric(key *[32]byte) macGeneric {
+	m := macGeneric{}
+	initialize(key, &m.macState)
+	return m
+}
+
+// macState holds numbers in saturated 64-bit little-endian limbs. That is,
+// the value of [x0, x1, x2] is x[0] + x[1] * 2⁶⁴ + x[2] * 2¹²⁸.
+type macState struct {
+	// h is the main accumulator. It is to be interpreted modulo 2¹³⁰ - 5, but
+	// can grow larger during and after rounds. It must, however, remain below
+	// 2 * (2¹³⁰ - 5).
+	h [3]uint64
+	// r and s are the private key components.
+	r [2]uint64
+	s [2]uint64
+}
+
+type macGeneric struct {
+	macState
+
+	buffer [TagSize]byte
+	offset int
+}
+
+// Write splits the incoming message into TagSize chunks, and passes them to
+// update. It buffers incomplete chunks.
+func (h *macGeneric) Write(p []byte) (int, error) {
+	nn := len(p)
+	if h.offset > 0 {
+		n := copy(h.buffer[h.offset:], p)
+		if h.offset+n < TagSize {
+			h.offset += n
+			return nn, nil
+		}
+		p = p[n:]
+		h.offset = 0
+		updateGeneric(&h.macState, h.buffer[:])
+	}
+	if n := len(p) - (len(p) % TagSize); n > 0 {
+		updateGeneric(&h.macState, p[:n])
+		p = p[n:]
+	}
+	if len(p) > 0 {
+		h.offset += copy(h.buffer[h.offset:], p)
+	}
+	return nn, nil
+}
+
+// Sum flushes the last incomplete chunk from the buffer, if any, and generates
+// the MAC output. It does not modify its state, in order to allow for multiple
+// calls to Sum, even if no Write is allowed after Sum.
+func (h *macGeneric) Sum(out *[TagSize]byte) {
+	state := h.macState
+	if h.offset > 0 {
+		updateGeneric(&state, h.buffer[:h.offset])
+	}
+	finalize(out, &state.h, &state.s)
+}
+
+// [rMask0, rMask1] is the specified Poly1305 clamping mask in little-endian. It
+// clears some bits of the secret coefficient to make it possible to implement
+// multiplication more efficiently.
+const (
+	rMask0 = 0x0FFFFFFC0FFFFFFF
+	rMask1 = 0x0FFFFFFC0FFFFFFC
+)
+
+// initialize loads the 256-bit key into the two 128-bit secret values r and s.
+func initialize(key *[32]byte, m *macState) {
+	m.r[0] = binary.LittleEndian.Uint64(key[0:8]) & rMask0
+	m.r[1] = binary.LittleEndian.Uint64(key[8:16]) & rMask1
+	m.s[0] = binary.LittleEndian.Uint64(key[16:24])
+	m.s[1] = binary.LittleEndian.Uint64(key[24:32])
+}
+
+// uint128 holds a 128-bit number as two 64-bit limbs, for use with the
+// bits.Mul64 and bits.Add64 intrinsics.
+type uint128 struct {
+	lo, hi uint64
+}
+
+func mul64(a, b uint64) uint128 {
+	hi, lo := bits.Mul64(a, b)
+	return uint128{lo, hi}
+}
+
+func add128(a, b uint128) uint128 {
+	lo, c := bits.Add64(a.lo, b.lo, 0)
+	hi, c := bits.Add64(a.hi, b.hi, c)
+	if c != 0 {
+		panic("poly1305: unexpected overflow")
+	}
+	return uint128{lo, hi}
+}
+
+func shiftRightBy2(a uint128) uint128 {
+	a.lo = a.lo>>2 | (a.hi&3)<<62
+	a.hi = a.hi >> 2
+	return a
+}
+
+// updateGeneric absorbs msg into the state.h accumulator. For each chunk m of
+// 128 bits of message, it computes
+//
+//	h₊ = (h + m) * r  mod  2¹³⁰ - 5
+//
+// If the msg length is not a multiple of TagSize, it assumes the last
+// incomplete chunk is the final one.
+func updateGeneric(state *macState, msg []byte) {
+	h0, h1, h2 := state.h[0], state.h[1], state.h[2]
+	r0, r1 := state.r[0], state.r[1]
+
+	for len(msg) > 0 {
+		var c uint64
+
+		// For the first step, h + m, we use a chain of bits.Add64 intrinsics.
+		// The resulting value of h might exceed 2¹³⁰ - 5, but will be partially
+		// reduced at the end of the multiplication below.
+		//
+		// The spec requires us to set a bit just above the message size, not to
+		// hide leading zeroes. For full chunks, that's 1 << 128, so we can just
+		// add 1 to the most significant (2¹²⁸) limb, h2.
+		if len(msg) >= TagSize {
+			h0, c = bits.Add64(h0, binary.LittleEndian.Uint64(msg[0:8]), 0)
+			h1, c = bits.Add64(h1, binary.LittleEndian.Uint64(msg[8:16]), c)
+			h2 += c + 1
+
+			msg = msg[TagSize:]
+		} else {
+			var buf [TagSize]byte
+			copy(buf[:], msg)
+			buf[len(msg)] = 1
+
+			h0, c = bits.Add64(h0, binary.LittleEndian.Uint64(buf[0:8]), 0)
+			h1, c = bits.Add64(h1, binary.LittleEndian.Uint64(buf[8:16]), c)
+			h2 += c
+
+			msg = nil
+		}
+
+		// Multiplication of big number limbs is similar to elementary school
+		// columnar multiplication. Instead of digits, there are 64-bit limbs.
+		//
+		// We are multiplying a 3 limbs number, h, by a 2 limbs number, r.
+		//
+		//                        h2    h1    h0  x
+		//                              r1    r0  =
+		//                       ----------------
+		//                      h2r0  h1r0  h0r0     <-- individual 128-bit products
+		//            +   h2r1  h1r1  h0r1
+		//               ------------------------
+		//                 m3    m2    m1    m0      <-- result in 128-bit overlapping limbs
+		//               ------------------------
+		//         m3.hi m2.hi m1.hi m0.hi           <-- carry propagation
+		//     +         m3.lo m2.lo m1.lo m0.lo
+		//        -------------------------------
+		//           t4    t3    t2    t1    t0      <-- final result in 64-bit limbs
+		//
+		// The main difference from pen-and-paper multiplication is that we do
+		// carry propagation in a separate step, as if we wrote two digit sums
+		// at first (the 128-bit limbs), and then carried the tens all at once.
+
+		h0r0 := mul64(h0, r0)
+		h1r0 := mul64(h1, r0)
+		h2r0 := mul64(h2, r0)
+		h0r1 := mul64(h0, r1)
+		h1r1 := mul64(h1, r1)
+		h2r1 := mul64(h2, r1)
+
+		// Since h2 is known to be at most 7 (5 + 1 + 1), and r0 and r1 have their
+		// top 4 bits cleared by rMask{0,1}, we know that their product is not going
+		// to overflow 64 bits, so we can ignore the high part of the products.
+		//
+		// This also means that the product doesn't have a fifth limb (t4).
+		if h2r0.hi != 0 {
+			panic("poly1305: unexpected overflow")
+		}
+		if h2r1.hi != 0 {
+			panic("poly1305: unexpected overflow")
+		}
+
+		m0 := h0r0
+		m1 := add128(h1r0, h0r1) // These two additions don't overflow thanks again
+		m2 := add128(h2r0, h1r1) // to the 4 masked bits at the top of r0 and r1.
+		m3 := h2r1
+
+		t0 := m0.lo
+		t1, c := bits.Add64(m1.lo, m0.hi, 0)
+		t2, c := bits.Add64(m2.lo, m1.hi, c)
+		t3, _ := bits.Add64(m3.lo, m2.hi, c)
+
+		// Now we have the result as 4 64-bit limbs, and we need to reduce it
+		// modulo 2¹³⁰ - 5. The special shape of this Crandall prime lets us do
+		// a cheap partial reduction according to the reduction identity
+		//
+		//     c * 2¹³⁰ + n  =  c * 5 + n  mod  2¹³⁰ - 5
+		//
+		// because 2¹³⁰ = 5 mod 2¹³⁰ - 5. Partial reduction since the result is
+		// likely to be larger than 2¹³⁰ - 5, but still small enough to fit the
+		// assumptions we make about h in the rest of the code.
+		//
+		// See also https://speakerdeck.com/gtank/engineering-prime-numbers?slide=23
+
+		// We split the final result at the 2¹³⁰ mark into h and cc, the carry.
+		// Note that the carry bits are effectively shifted left by 2, in other
+		// words, cc = c * 4 for the c in the reduction identity.
+		h0, h1, h2 = t0, t1, t2&maskLow2Bits
+		cc := uint128{t2 & maskNotLow2Bits, t3}
+
+		// To add c * 5 to h, we first add cc = c * 4, and then add (cc >> 2) = c.
+
+		h0, c = bits.Add64(h0, cc.lo, 0)
+		h1, c = bits.Add64(h1, cc.hi, c)
+		h2 += c
+
+		cc = shiftRightBy2(cc)
+
+		h0, c = bits.Add64(h0, cc.lo, 0)
+		h1, c = bits.Add64(h1, cc.hi, c)
+		h2 += c
+
+		// h2 is at most 3 + 1 + 1 = 5, making the whole of h at most
+		//
+		//     5 * 2¹²⁸ + (2¹²⁸ - 1) = 6 * 2¹²⁸ - 1
+	}
+
+	state.h[0], state.h[1], state.h[2] = h0, h1, h2
+}
+
+const (
+	maskLow2Bits    uint64 = 0x0000000000000003
+	maskNotLow2Bits uint64 = ^maskLow2Bits
+)
+
+// select64 returns x if v == 1 and y if v == 0, in constant time.
+func select64(v, x, y uint64) uint64 { return ^(v-1)&x | (v-1)&y }
+
+// [p0, p1, p2] is 2¹³⁰ - 5 in little endian order.
+const (
+	p0 = 0xFFFFFFFFFFFFFFFB
+	p1 = 0xFFFFFFFFFFFFFFFF
+	p2 = 0x0000000000000003
+)
+
+// finalize completes the modular reduction of h and computes
+//
+//	out = h + s  mod  2¹²⁸
+func finalize(out *[TagSize]byte, h *[3]uint64, s *[2]uint64) {
+	h0, h1, h2 := h[0], h[1], h[2]
+
+	// After the partial reduction in updateGeneric, h might be more than
+	// 2¹³⁰ - 5, but will be less than 2 * (2¹³⁰ - 5). To complete the reduction
+	// in constant time, we compute t = h - (2¹³⁰ - 5), and select h as the
+	// result if the subtraction underflows, and t otherwise.
+
+	hMinusP0, b := bits.Sub64(h0, p0, 0)
+	hMinusP1, b := bits.Sub64(h1, p1, b)
+	_, b = bits.Sub64(h2, p2, b)
+
+	// h = h if h < p else h - p
+	h0 = select64(b, h0, hMinusP0)
+	h1 = select64(b, h1, hMinusP1)
+
+	// Finally, we compute the last Poly1305 step
+	//
+	//     tag = h + s  mod  2¹²⁸
+	//
+	// by just doing a wide addition with the 128 low bits of h and discarding
+	// the overflow.
+	h0, c := bits.Add64(h0, s[0], 0)
+	h1, _ = bits.Add64(h1, s[1], c)
+
+	binary.LittleEndian.PutUint64(out[0:8], h0)
+	binary.LittleEndian.PutUint64(out[8:16], h1)
+}
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_ppc64le.go b/vendor/golang.org/x/crypto/internal/poly1305/sum_ppc64le.go
new file mode 100644
index 000000000..4aec4874b
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_ppc64le.go
@@ -0,0 +1,47 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+package poly1305
+
+//go:noescape
+func update(state *macState, msg []byte)
+
+// mac is a wrapper for macGeneric that redirects calls that would have gone to
+// updateGeneric to update.
+//
+// Its Write and Sum methods are otherwise identical to the macGeneric ones, but
+// using function pointers would carry a major performance cost.
+type mac struct{ macGeneric }
+
+func (h *mac) Write(p []byte) (int, error) {
+	nn := len(p)
+	if h.offset > 0 {
+		n := copy(h.buffer[h.offset:], p)
+		if h.offset+n < TagSize {
+			h.offset += n
+			return nn, nil
+		}
+		p = p[n:]
+		h.offset = 0
+		update(&h.macState, h.buffer[:])
+	}
+	if n := len(p) - (len(p) % TagSize); n > 0 {
+		update(&h.macState, p[:n])
+		p = p[n:]
+	}
+	if len(p) > 0 {
+		h.offset += copy(h.buffer[h.offset:], p)
+	}
+	return nn, nil
+}
+
+func (h *mac) Sum(out *[16]byte) {
+	state := h.macState
+	if h.offset > 0 {
+		update(&state, h.buffer[:h.offset])
+	}
+	finalize(out, &state.h, &state.s)
+}
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_ppc64le.s b/vendor/golang.org/x/crypto/internal/poly1305/sum_ppc64le.s
new file mode 100644
index 000000000..b3c1699bf
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_ppc64le.s
@@ -0,0 +1,179 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+#include "textflag.h"
+
+// This was ported from the amd64 implementation.
+
+#define POLY1305_ADD(msg, h0, h1, h2, t0, t1, t2) \
+	MOVD (msg), t0;  \
+	MOVD 8(msg), t1; \
+	MOVD $1, t2;     \
+	ADDC t0, h0, h0; \
+	ADDE t1, h1, h1; \
+	ADDE t2, h2;     \
+	ADD  $16, msg
+
+#define POLY1305_MUL(h0, h1, h2, r0, r1, t0, t1, t2, t3, t4, t5) \
+	MULLD  r0, h0, t0;  \
+	MULHDU r0, h0, t1;  \
+	MULLD  r0, h1, t4;  \
+	MULHDU r0, h1, t5;  \
+	ADDC   t4, t1, t1;  \
+	MULLD  r0, h2, t2;  \
+	MULHDU r1, h0, t4;  \
+	MULLD  r1, h0, h0;  \
+	ADDE   t5, t2, t2;  \
+	ADDC   h0, t1, t1;  \
+	MULLD  h2, r1, t3;  \
+	ADDZE  t4, h0;      \
+	MULHDU r1, h1, t5;  \
+	MULLD  r1, h1, t4;  \
+	ADDC   t4, t2, t2;  \
+	ADDE   t5, t3, t3;  \
+	ADDC   h0, t2, t2;  \
+	MOVD   $-4, t4;     \
+	ADDZE  t3;          \
+	RLDICL $0, t2, $62, h2; \
+	AND    t2, t4, h0;  \
+	ADDC   t0, h0, h0;  \
+	ADDE   t3, t1, h1;  \
+	SLD    $62, t3, t4; \
+	SRD    $2, t2;      \
+	ADDZE  h2;          \
+	OR     t4, t2, t2;  \
+	SRD    $2, t3;      \
+	ADDC   t2, h0, h0;  \
+	ADDE   t3, h1, h1;  \
+	ADDZE  h2
+
+DATA ·poly1305Mask<>+0x00(SB)/8, $0x0FFFFFFC0FFFFFFF
+DATA ·poly1305Mask<>+0x08(SB)/8, $0x0FFFFFFC0FFFFFFC
+GLOBL ·poly1305Mask<>(SB), RODATA, $16
+
+// func update(state *[7]uint64, msg []byte)
+TEXT ·update(SB), $0-32
+	MOVD state+0(FP), R3
+	MOVD msg_base+8(FP), R4
+	MOVD msg_len+16(FP), R5
+
+	MOVD 0(R3), R8   // h0
+	MOVD 8(R3), R9   // h1
+	MOVD 16(R3), R10 // h2
+	MOVD 24(R3), R11 // r0
+	MOVD 32(R3), R12 // r1
+
+	CMP R5, $16
+	BLT bytes_between_0_and_15
+
+loop:
+	POLY1305_ADD(R4, R8, R9, R10, R20, R21, R22)
+
+	PCALIGN $16
+multiply:
+	POLY1305_MUL(R8, R9, R10, R11, R12, R16, R17, R18, R14, R20, R21)
+	ADD $-16, R5
+	CMP R5, $16
+	BGE loop
+
+bytes_between_0_and_15:
+	CMP  R5, $0
+	BEQ  done
+	MOVD $0, R16 // h0
+	MOVD $0, R17 // h1
+
+flush_buffer:
+	CMP R5, $8
+	BLE just1
+
+	MOVD $8, R21
+	SUB  R21, R5, R21
+
+	// Greater than 8 -- load the rightmost remaining bytes in msg
+	// and put into R17 (h1)
+	MOVD (R4)(R21), R17
+	MOVD $16, R22
+
+	// Find the offset to those bytes
+	SUB R5, R22, R22
+	SLD $3, R22
+
+	// Shift to get only the bytes in msg
+	SRD R22, R17, R17
+
+	// Put 1 at high end
+	MOVD $1, R23
+	SLD  $3, R21
+	SLD  R21, R23, R23
+	OR   R23, R17, R17
+
+	// Remainder is 8
+	MOVD $8, R5
+
+just1:
+	CMP R5, $8
+	BLT less8
+
+	// Exactly 8
+	MOVD (R4), R16
+
+	CMP R17, $0
+
+	// Check if we've already set R17; if not
+	// set 1 to indicate end of msg.
+	BNE  carry
+	MOVD $1, R17
+	BR   carry
+
+less8:
+	MOVD  $0, R16   // h0
+	MOVD  $0, R22   // shift count
+	CMP   R5, $4
+	BLT   less4
+	MOVWZ (R4), R16
+	ADD   $4, R4
+	ADD   $-4, R5
+	MOVD  $32, R22
+
+less4:
+	CMP   R5, $2
+	BLT   less2
+	MOVHZ (R4), R21
+	SLD   R22, R21, R21
+	OR    R16, R21, R16
+	ADD   $16, R22
+	ADD   $-2, R5
+	ADD   $2, R4
+
+less2:
+	CMP   R5, $0
+	BEQ   insert1
+	MOVBZ (R4), R21
+	SLD   R22, R21, R21
+	OR    R16, R21, R16
+	ADD   $8, R22
+
+insert1:
+	// Insert 1 at end of msg
+	MOVD $1, R21
+	SLD  R22, R21, R21
+	OR   R16, R21, R16
+
+carry:
+	// Add new values to h0, h1, h2
+	ADDC  R16, R8
+	ADDE  R17, R9
+	ADDZE R10, R10
+	MOVD  $16, R5
+	ADD   R5, R4
+	BR    multiply
+
+done:
+	// Save h0, h1, h2 in state
+	MOVD R8, 0(R3)
+	MOVD R9, 8(R3)
+	MOVD R10, 16(R3)
+	RET
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_s390x.go b/vendor/golang.org/x/crypto/internal/poly1305/sum_s390x.go
new file mode 100644
index 000000000..e1d033a49
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_s390x.go
@@ -0,0 +1,76 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+package poly1305
+
+import (
+	"golang.org/x/sys/cpu"
+)
+
+// updateVX is an assembly implementation of Poly1305 that uses vector
+// instructions. It must only be called if the vector facility (vx) is
+// available.
+//
+//go:noescape
+func updateVX(state *macState, msg []byte)
+
+// mac is a replacement for macGeneric that uses a larger buffer and redirects
+// calls that would have gone to updateGeneric to updateVX if the vector
+// facility is installed.
+//
+// A larger buffer is required for good performance because the vector
+// implementation has a higher fixed cost per call than the generic
+// implementation.
+type mac struct {
+	macState
+
+	buffer [16 * TagSize]byte // size must be a multiple of block size (16)
+	offset int
+}
+
+func (h *mac) Write(p []byte) (int, error) {
+	nn := len(p)
+	if h.offset > 0 {
+		n := copy(h.buffer[h.offset:], p)
+		if h.offset+n < len(h.buffer) {
+			h.offset += n
+			return nn, nil
+		}
+		p = p[n:]
+		h.offset = 0
+		if cpu.S390X.HasVX {
+			updateVX(&h.macState, h.buffer[:])
+		} else {
+			updateGeneric(&h.macState, h.buffer[:])
+		}
+	}
+
+	tail := len(p) % len(h.buffer) // number of bytes to copy into buffer
+	body := len(p) - tail          // number of bytes to process now
+	if body > 0 {
+		if cpu.S390X.HasVX {
+			updateVX(&h.macState, p[:body])
+		} else {
+			updateGeneric(&h.macState, p[:body])
+		}
+	}
+	h.offset = copy(h.buffer[:], p[body:]) // copy tail bytes - can be 0
+	return nn, nil
+}
+
+func (h *mac) Sum(out *[TagSize]byte) {
+	state := h.macState
+	remainder := h.buffer[:h.offset]
+
+	// Use the generic implementation if we have 2 or fewer blocks left
+	// to sum. The vector implementation has a higher startup time.
+	if cpu.S390X.HasVX && len(remainder) > 2*TagSize {
+		updateVX(&state, remainder)
+	} else if len(remainder) > 0 {
+		updateGeneric(&state, remainder)
+	}
+	finalize(out, &state.h, &state.s)
+}
diff --git a/vendor/golang.org/x/crypto/internal/poly1305/sum_s390x.s b/vendor/golang.org/x/crypto/internal/poly1305/sum_s390x.s
new file mode 100644
index 000000000..0fe3a7c21
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/poly1305/sum_s390x.s
@@ -0,0 +1,503 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc && !purego
+
+#include "textflag.h"
+
+// This implementation of Poly1305 uses the vector facility (vx)
+// to process up to 2 blocks (32 bytes) per iteration using an
+// algorithm based on the one described in:
+//
+// NEON crypto, Daniel J. Bernstein & Peter Schwabe
+// https://cryptojedi.org/papers/neoncrypto-20120320.pdf
+//
+// This algorithm uses 5 26-bit limbs to represent a 130-bit
+// value. These limbs are, for the most part, zero extended and
+// placed into 64-bit vector register elements. Each vector
+// register is 128-bits wide and so holds 2 of these elements.
+// Using 26-bit limbs allows us plenty of headroom to accommodate
+// accumulations before and after multiplication without
+// overflowing either 32-bits (before multiplication) or 64-bits
+// (after multiplication).
+//
+// In order to parallelise the operations required to calculate
+// the sum we use two separate accumulators and then sum those
+// in an extra final step. For compatibility with the generic
+// implementation we perform this summation at the end of every
+// updateVX call.
+//
+// To use two accumulators we must multiply the message blocks
+// by r² rather than r. Only the final message block should be
+// multiplied by r.
+//
+// Example:
+//
+// We want to calculate the sum (h) for a 64 byte message (m):
+//
+//   h = m[0:16]r⁴ + m[16:32]r³ + m[32:48]r² + m[48:64]r
+//
+// To do this we split the calculation into the even indices
+// and odd indices of the message. These form our SIMD 'lanes':
+//
+//   h = m[ 0:16]r⁴ + m[32:48]r² +   <- lane 0
+//       m[16:32]r³ + m[48:64]r      <- lane 1
+//
+// To calculate this iteratively we refactor so that both lanes
+// are written in terms of r² and r:
+//
+//   h = (m[ 0:16]r² + m[32:48])r² + <- lane 0
+//       (m[16:32]r² + m[48:64])r    <- lane 1
+//                ^             ^
+//                |             coefficients for second iteration
+//                coefficients for first iteration
+//
+// So in this case we would have two iterations. In the first
+// both lanes are multiplied by r². In the second only the
+// first lane is multiplied by r² and the second lane is
+// instead multiplied by r. This gives use the odd and even
+// powers of r that we need from the original equation.
+//
+// Notation:
+//
+//   h - accumulator
+//   r - key
+//   m - message
+//
+//   [a, b]       - SIMD register holding two 64-bit values
+//   [a, b, c, d] - SIMD register holding four 32-bit values
+//   xᵢ[n]        - limb n of variable x with bit width i
+//
+// Limbs are expressed in little endian order, so for 26-bit
+// limbs x₂₆[4] will be the most significant limb and x₂₆[0]
+// will be the least significant limb.
+
+// masking constants
+#define MOD24 V0 // [0x0000000000ffffff, 0x0000000000ffffff] - mask low 24-bits
+#define MOD26 V1 // [0x0000000003ffffff, 0x0000000003ffffff] - mask low 26-bits
+
+// expansion constants (see EXPAND macro)
+#define EX0 V2
+#define EX1 V3
+#define EX2 V4
+
+// key (r², r or 1 depending on context)
+#define R_0 V5
+#define R_1 V6
+#define R_2 V7
+#define R_3 V8
+#define R_4 V9
+
+// precalculated coefficients (5r², 5r or 0 depending on context)
+#define R5_1 V10
+#define R5_2 V11
+#define R5_3 V12
+#define R5_4 V13
+
+// message block (m)
+#define M_0 V14
+#define M_1 V15
+#define M_2 V16
+#define M_3 V17
+#define M_4 V18
+
+// accumulator (h)
+#define H_0 V19
+#define H_1 V20
+#define H_2 V21
+#define H_3 V22
+#define H_4 V23
+
+// temporary registers (for short-lived values)
+#define T_0 V24
+#define T_1 V25
+#define T_2 V26
+#define T_3 V27
+#define T_4 V28
+
+GLOBL ·constants<>(SB), RODATA, $0x30
+// EX0
+DATA ·constants<>+0x00(SB)/8, $0x0006050403020100
+DATA ·constants<>+0x08(SB)/8, $0x1016151413121110
+// EX1
+DATA ·constants<>+0x10(SB)/8, $0x060c0b0a09080706
+DATA ·constants<>+0x18(SB)/8, $0x161c1b1a19181716
+// EX2
+DATA ·constants<>+0x20(SB)/8, $0x0d0d0d0d0d0f0e0d
+DATA ·constants<>+0x28(SB)/8, $0x1d1d1d1d1d1f1e1d
+
+// MULTIPLY multiplies each lane of f and g, partially reduced
+// modulo 2¹³⁰ - 5. The result, h, consists of partial products
+// in each lane that need to be reduced further to produce the
+// final result.
+//
+//   h₁₃₀ = (f₁₃₀g₁₃₀) % 2¹³⁰ + (5f₁₃₀g₁₃₀) / 2¹³⁰
+//
+// Note that the multiplication by 5 of the high bits is
+// achieved by precalculating the multiplication of four of the
+// g coefficients by 5. These are g51-g54.
+#define MULTIPLY(f0, f1, f2, f3, f4, g0, g1, g2, g3, g4, g51, g52, g53, g54, h0, h1, h2, h3, h4) \
+	VMLOF  f0, g0, h0        \
+	VMLOF  f0, g3, h3        \
+	VMLOF  f0, g1, h1        \
+	VMLOF  f0, g4, h4        \
+	VMLOF  f0, g2, h2        \
+	VMLOF  f1, g54, T_0      \
+	VMLOF  f1, g2, T_3       \
+	VMLOF  f1, g0, T_1       \
+	VMLOF  f1, g3, T_4       \
+	VMLOF  f1, g1, T_2       \
+	VMALOF f2, g53, h0, h0   \
+	VMALOF f2, g1, h3, h3    \
+	VMALOF f2, g54, h1, h1   \
+	VMALOF f2, g2, h4, h4    \
+	VMALOF f2, g0, h2, h2    \
+	VMALOF f3, g52, T_0, T_0 \
+	VMALOF f3, g0, T_3, T_3  \
+	VMALOF f3, g53, T_1, T_1 \
+	VMALOF f3, g1, T_4, T_4  \
+	VMALOF f3, g54, T_2, T_2 \
+	VMALOF f4, g51, h0, h0   \
+	VMALOF f4, g54, h3, h3   \
+	VMALOF f4, g52, h1, h1   \
+	VMALOF f4, g0, h4, h4    \
+	VMALOF f4, g53, h2, h2   \
+	VAG    T_0, h0, h0       \
+	VAG    T_3, h3, h3       \
+	VAG    T_1, h1, h1       \
+	VAG    T_4, h4, h4       \
+	VAG    T_2, h2, h2
+
+// REDUCE performs the following carry operations in four
+// stages, as specified in Bernstein & Schwabe:
+//
+//   1: h₂₆[0]->h₂₆[1] h₂₆[3]->h₂₆[4]
+//   2: h₂₆[1]->h₂₆[2] h₂₆[4]->h₂₆[0]
+//   3: h₂₆[0]->h₂₆[1] h₂₆[2]->h₂₆[3]
+//   4: h₂₆[3]->h₂₆[4]
+//
+// The result is that all of the limbs are limited to 26-bits
+// except for h₂₆[1] and h₂₆[4] which are limited to 27-bits.
+//
+// Note that although each limb is aligned at 26-bit intervals
+// they may contain values that exceed 2²⁶ - 1, hence the need
+// to carry the excess bits in each limb.
+#define REDUCE(h0, h1, h2, h3, h4) \
+	VESRLG $26, h0, T_0  \
+	VESRLG $26, h3, T_1  \
+	VN     MOD26, h0, h0 \
+	VN     MOD26, h3, h3 \
+	VAG    T_0, h1, h1   \
+	VAG    T_1, h4, h4   \
+	VESRLG $26, h1, T_2  \
+	VESRLG $26, h4, T_3  \
+	VN     MOD26, h1, h1 \
+	VN     MOD26, h4, h4 \
+	VESLG  $2, T_3, T_4  \
+	VAG    T_3, T_4, T_4 \
+	VAG    T_2, h2, h2   \
+	VAG    T_4, h0, h0   \
+	VESRLG $26, h2, T_0  \
+	VESRLG $26, h0, T_1  \
+	VN     MOD26, h2, h2 \
+	VN     MOD26, h0, h0 \
+	VAG    T_0, h3, h3   \
+	VAG    T_1, h1, h1   \
+	VESRLG $26, h3, T_2  \
+	VN     MOD26, h3, h3 \
+	VAG    T_2, h4, h4
+
+// EXPAND splits the 128-bit little-endian values in0 and in1
+// into 26-bit big-endian limbs and places the results into
+// the first and second lane of d₂₆[0:4] respectively.
+//
+// The EX0, EX1 and EX2 constants are arrays of byte indices
+// for permutation. The permutation both reverses the bytes
+// in the input and ensures the bytes are copied into the
+// destination limb ready to be shifted into their final
+// position.
+#define EXPAND(in0, in1, d0, d1, d2, d3, d4) \
+	VPERM  in0, in1, EX0, d0 \
+	VPERM  in0, in1, EX1, d2 \
+	VPERM  in0, in1, EX2, d4 \
+	VESRLG $26, d0, d1       \
+	VESRLG $30, d2, d3       \
+	VESRLG $4, d2, d2        \
+	VN     MOD26, d0, d0     \ // [in0₂₆[0], in1₂₆[0]]
+	VN     MOD26, d3, d3     \ // [in0₂₆[3], in1₂₆[3]]
+	VN     MOD26, d1, d1     \ // [in0₂₆[1], in1₂₆[1]]
+	VN     MOD24, d4, d4     \ // [in0₂₆[4], in1₂₆[4]]
+	VN     MOD26, d2, d2     // [in0₂₆[2], in1₂₆[2]]
+
+// func updateVX(state *macState, msg []byte)
+TEXT ·updateVX(SB), NOSPLIT, $0
+	MOVD state+0(FP), R1
+	LMG  msg+8(FP), R2, R3 // R2=msg_base, R3=msg_len
+
+	// load EX0, EX1 and EX2
+	MOVD $·constants<>(SB), R5
+	VLM  (R5), EX0, EX2
+
+	// generate masks
+	VGMG $(64-24), $63, MOD24 // [0x00ffffff, 0x00ffffff]
+	VGMG $(64-26), $63, MOD26 // [0x03ffffff, 0x03ffffff]
+
+	// load h (accumulator) and r (key) from state
+	VZERO T_1               // [0, 0]
+	VL    0(R1), T_0        // [h₆₄[0], h₆₄[1]]
+	VLEG  $0, 16(R1), T_1   // [h₆₄[2], 0]
+	VL    24(R1), T_2       // [r₆₄[0], r₆₄[1]]
+	VPDI  $0, T_0, T_2, T_3 // [h₆₄[0], r₆₄[0]]
+	VPDI  $5, T_0, T_2, T_4 // [h₆₄[1], r₆₄[1]]
+
+	// unpack h and r into 26-bit limbs
+	// note: h₆₄[2] may have the low 3 bits set, so h₂₆[4] is a 27-bit value
+	VN     MOD26, T_3, H_0            // [h₂₆[0], r₂₆[0]]
+	VZERO  H_1                        // [0, 0]
+	VZERO  H_3                        // [0, 0]
+	VGMG   $(64-12-14), $(63-12), T_0 // [0x03fff000, 0x03fff000] - 26-bit mask with low 12 bits masked out
+	VESLG  $24, T_1, T_1              // [h₆₄[2]<<24, 0]
+	VERIMG $-26&63, T_3, MOD26, H_1   // [h₂₆[1], r₂₆[1]]
+	VESRLG $+52&63, T_3, H_2          // [h₂₆[2], r₂₆[2]] - low 12 bits only
+	VERIMG $-14&63, T_4, MOD26, H_3   // [h₂₆[1], r₂₆[1]]
+	VESRLG $40, T_4, H_4              // [h₂₆[4], r₂₆[4]] - low 24 bits only
+	VERIMG $+12&63, T_4, T_0, H_2     // [h₂₆[2], r₂₆[2]] - complete
+	VO     T_1, H_4, H_4              // [h₂₆[4], r₂₆[4]] - complete
+
+	// replicate r across all 4 vector elements
+	VREPF $3, H_0, R_0 // [r₂₆[0], r₂₆[0], r₂₆[0], r₂₆[0]]
+	VREPF $3, H_1, R_1 // [r₂₆[1], r₂₆[1], r₂₆[1], r₂₆[1]]
+	VREPF $3, H_2, R_2 // [r₂₆[2], r₂₆[2], r₂₆[2], r₂₆[2]]
+	VREPF $3, H_3, R_3 // [r₂₆[3], r₂₆[3], r₂₆[3], r₂₆[3]]
+	VREPF $3, H_4, R_4 // [r₂₆[4], r₂₆[4], r₂₆[4], r₂₆[4]]
+
+	// zero out lane 1 of h
+	VLEIG $1, $0, H_0 // [h₂₆[0], 0]
+	VLEIG $1, $0, H_1 // [h₂₆[1], 0]
+	VLEIG $1, $0, H_2 // [h₂₆[2], 0]
+	VLEIG $1, $0, H_3 // [h₂₆[3], 0]
+	VLEIG $1, $0, H_4 // [h₂₆[4], 0]
+
+	// calculate 5r (ignore least significant limb)
+	VREPIF $5, T_0
+	VMLF   T_0, R_1, R5_1 // [5r₂₆[1], 5r₂₆[1], 5r₂₆[1], 5r₂₆[1]]
+	VMLF   T_0, R_2, R5_2 // [5r₂₆[2], 5r₂₆[2], 5r₂₆[2], 5r₂₆[2]]
+	VMLF   T_0, R_3, R5_3 // [5r₂₆[3], 5r₂₆[3], 5r₂₆[3], 5r₂₆[3]]
+	VMLF   T_0, R_4, R5_4 // [5r₂₆[4], 5r₂₆[4], 5r₂₆[4], 5r₂₆[4]]
+
+	// skip r² calculation if we are only calculating one block
+	CMPBLE R3, $16, skip
+
+	// calculate r²
+	MULTIPLY(R_0, R_1, R_2, R_3, R_4, R_0, R_1, R_2, R_3, R_4, R5_1, R5_2, R5_3, R5_4, M_0, M_1, M_2, M_3, M_4)
+	REDUCE(M_0, M_1, M_2, M_3, M_4)
+	VGBM   $0x0f0f, T_0
+	VERIMG $0, M_0, T_0, R_0 // [r₂₆[0], r²₂₆[0], r₂₆[0], r²₂₆[0]]
+	VERIMG $0, M_1, T_0, R_1 // [r₂₆[1], r²₂₆[1], r₂₆[1], r²₂₆[1]]
+	VERIMG $0, M_2, T_0, R_2 // [r₂₆[2], r²₂₆[2], r₂₆[2], r²₂₆[2]]
+	VERIMG $0, M_3, T_0, R_3 // [r₂₆[3], r²₂₆[3], r₂₆[3], r²₂₆[3]]
+	VERIMG $0, M_4, T_0, R_4 // [r₂₆[4], r²₂₆[4], r₂₆[4], r²₂₆[4]]
+
+	// calculate 5r² (ignore least significant limb)
+	VREPIF $5, T_0
+	VMLF   T_0, R_1, R5_1 // [5r₂₆[1], 5r²₂₆[1], 5r₂₆[1], 5r²₂₆[1]]
+	VMLF   T_0, R_2, R5_2 // [5r₂₆[2], 5r²₂₆[2], 5r₂₆[2], 5r²₂₆[2]]
+	VMLF   T_0, R_3, R5_3 // [5r₂₆[3], 5r²₂₆[3], 5r₂₆[3], 5r²₂₆[3]]
+	VMLF   T_0, R_4, R5_4 // [5r₂₆[4], 5r²₂₆[4], 5r₂₆[4], 5r²₂₆[4]]
+
+loop:
+	CMPBLE R3, $32, b2 // 2 or fewer blocks remaining, need to change key coefficients
+
+	// load next 2 blocks from message
+	VLM (R2), T_0, T_1
+
+	// update message slice
+	SUB  $32, R3
+	MOVD $32(R2), R2
+
+	// unpack message blocks into 26-bit big-endian limbs
+	EXPAND(T_0, T_1, M_0, M_1, M_2, M_3, M_4)
+
+	// add 2¹²⁸ to each message block value
+	VLEIB $4, $1, M_4
+	VLEIB $12, $1, M_4
+
+multiply:
+	// accumulate the incoming message
+	VAG H_0, M_0, M_0
+	VAG H_3, M_3, M_3
+	VAG H_1, M_1, M_1
+	VAG H_4, M_4, M_4
+	VAG H_2, M_2, M_2
+
+	// multiply the accumulator by the key coefficient
+	MULTIPLY(M_0, M_1, M_2, M_3, M_4, R_0, R_1, R_2, R_3, R_4, R5_1, R5_2, R5_3, R5_4, H_0, H_1, H_2, H_3, H_4)
+
+	// carry and partially reduce the partial products
+	REDUCE(H_0, H_1, H_2, H_3, H_4)
+
+	CMPBNE R3, $0, loop
+
+finish:
+	// sum lane 0 and lane 1 and put the result in lane 1
+	VZERO  T_0
+	VSUMQG H_0, T_0, H_0
+	VSUMQG H_3, T_0, H_3
+	VSUMQG H_1, T_0, H_1
+	VSUMQG H_4, T_0, H_4
+	VSUMQG H_2, T_0, H_2
+
+	// reduce again after summation
+	// TODO(mundaym): there might be a more efficient way to do this
+	// now that we only have 1 active lane. For example, we could
+	// simultaneously pack the values as we reduce them.
+	REDUCE(H_0, H_1, H_2, H_3, H_4)
+
+	// carry h[1] through to h[4] so that only h[4] can exceed 2²⁶ - 1
+	// TODO(mundaym): in testing this final carry was unnecessary.
+	// Needs a proof before it can be removed though.
+	VESRLG $26, H_1, T_1
+	VN     MOD26, H_1, H_1
+	VAQ    T_1, H_2, H_2
+	VESRLG $26, H_2, T_2
+	VN     MOD26, H_2, H_2
+	VAQ    T_2, H_3, H_3
+	VESRLG $26, H_3, T_3
+	VN     MOD26, H_3, H_3
+	VAQ    T_3, H_4, H_4
+
+	// h is now < 2(2¹³⁰ - 5)
+	// Pack each lane in h₂₆[0:4] into h₁₂₈[0:1].
+	VESLG $26, H_1, H_1
+	VESLG $26, H_3, H_3
+	VO    H_0, H_1, H_0
+	VO    H_2, H_3, H_2
+	VESLG $4, H_2, H_2
+	VLEIB $7, $48, H_1
+	VSLB  H_1, H_2, H_2
+	VO    H_0, H_2, H_0
+	VLEIB $7, $104, H_1
+	VSLB  H_1, H_4, H_3
+	VO    H_3, H_0, H_0
+	VLEIB $7, $24, H_1
+	VSRLB H_1, H_4, H_1
+
+	// update state
+	VSTEG $1, H_0, 0(R1)
+	VSTEG $0, H_0, 8(R1)
+	VSTEG $1, H_1, 16(R1)
+	RET
+
+b2:  // 2 or fewer blocks remaining
+	CMPBLE R3, $16, b1
+
+	// Load the 2 remaining blocks (17-32 bytes remaining).
+	MOVD $-17(R3), R0    // index of final byte to load modulo 16
+	VL   (R2), T_0       // load full 16 byte block
+	VLL  R0, 16(R2), T_1 // load final (possibly partial) block and pad with zeros to 16 bytes
+
+	// The Poly1305 algorithm requires that a 1 bit be appended to
+	// each message block. If the final block is less than 16 bytes
+	// long then it is easiest to insert the 1 before the message
+	// block is split into 26-bit limbs. If, on the other hand, the
+	// final message block is 16 bytes long then we append the 1 bit
+	// after expansion as normal.
+	MOVBZ  $1, R0
+	MOVD   $-16(R3), R3   // index of byte in last block to insert 1 at (could be 16)
+	CMPBEQ R3, $16, 2(PC) // skip the insertion if the final block is 16 bytes long
+	VLVGB  R3, R0, T_1    // insert 1 into the byte at index R3
+
+	// Split both blocks into 26-bit limbs in the appropriate lanes.
+	EXPAND(T_0, T_1, M_0, M_1, M_2, M_3, M_4)
+
+	// Append a 1 byte to the end of the second to last block.
+	VLEIB $4, $1, M_4
+
+	// Append a 1 byte to the end of the last block only if it is a
+	// full 16 byte block.
+	CMPBNE R3, $16, 2(PC)
+	VLEIB  $12, $1, M_4
+
+	// Finally, set up the coefficients for the final multiplication.
+	// We have previously saved r and 5r in the 32-bit even indexes
+	// of the R_[0-4] and R5_[1-4] coefficient registers.
+	//
+	// We want lane 0 to be multiplied by r² so that can be kept the
+	// same. We want lane 1 to be multiplied by r so we need to move
+	// the saved r value into the 32-bit odd index in lane 1 by
+	// rotating the 64-bit lane by 32.
+	VGBM   $0x00ff, T_0         // [0, 0xffffffffffffffff] - mask lane 1 only
+	VERIMG $32, R_0, T_0, R_0   // [_,  r²₂₆[0], _,  r₂₆[0]]
+	VERIMG $32, R_1, T_0, R_1   // [_,  r²₂₆[1], _,  r₂₆[1]]
+	VERIMG $32, R_2, T_0, R_2   // [_,  r²₂₆[2], _,  r₂₆[2]]
+	VERIMG $32, R_3, T_0, R_3   // [_,  r²₂₆[3], _,  r₂₆[3]]
+	VERIMG $32, R_4, T_0, R_4   // [_,  r²₂₆[4], _,  r₂₆[4]]
+	VERIMG $32, R5_1, T_0, R5_1 // [_, 5r²₂₆[1], _, 5r₂₆[1]]
+	VERIMG $32, R5_2, T_0, R5_2 // [_, 5r²₂₆[2], _, 5r₂₆[2]]
+	VERIMG $32, R5_3, T_0, R5_3 // [_, 5r²₂₆[3], _, 5r₂₆[3]]
+	VERIMG $32, R5_4, T_0, R5_4 // [_, 5r²₂₆[4], _, 5r₂₆[4]]
+
+	MOVD $0, R3
+	BR   multiply
+
+skip:
+	CMPBEQ R3, $0, finish
+
+b1:  // 1 block remaining
+
+	// Load the final block (1-16 bytes). This will be placed into
+	// lane 0.
+	MOVD $-1(R3), R0
+	VLL  R0, (R2), T_0 // pad to 16 bytes with zeros
+
+	// The Poly1305 algorithm requires that a 1 bit be appended to
+	// each message block. If the final block is less than 16 bytes
+	// long then it is easiest to insert the 1 before the message
+	// block is split into 26-bit limbs. If, on the other hand, the
+	// final message block is 16 bytes long then we append the 1 bit
+	// after expansion as normal.
+	MOVBZ  $1, R0
+	CMPBEQ R3, $16, 2(PC)
+	VLVGB  R3, R0, T_0
+
+	// Set the message block in lane 1 to the value 0 so that it
+	// can be accumulated without affecting the final result.
+	VZERO T_1
+
+	// Split the final message block into 26-bit limbs in lane 0.
+	// Lane 1 will be contain 0.
+	EXPAND(T_0, T_1, M_0, M_1, M_2, M_3, M_4)
+
+	// Append a 1 byte to the end of the last block only if it is a
+	// full 16 byte block.
+	CMPBNE R3, $16, 2(PC)
+	VLEIB  $4, $1, M_4
+
+	// We have previously saved r and 5r in the 32-bit even indexes
+	// of the R_[0-4] and R5_[1-4] coefficient registers.
+	//
+	// We want lane 0 to be multiplied by r so we need to move the
+	// saved r value into the 32-bit odd index in lane 0. We want
+	// lane 1 to be set to the value 1. This makes multiplication
+	// a no-op. We do this by setting lane 1 in every register to 0
+	// and then just setting the 32-bit index 3 in R_0 to 1.
+	VZERO T_0
+	MOVD  $0, R0
+	MOVD  $0x10111213, R12
+	VLVGP R12, R0, T_1         // [_, 0x10111213, _, 0x00000000]
+	VPERM T_0, R_0, T_1, R_0   // [_,  r₂₆[0], _, 0]
+	VPERM T_0, R_1, T_1, R_1   // [_,  r₂₆[1], _, 0]
+	VPERM T_0, R_2, T_1, R_2   // [_,  r₂₆[2], _, 0]
+	VPERM T_0, R_3, T_1, R_3   // [_,  r₂₆[3], _, 0]
+	VPERM T_0, R_4, T_1, R_4   // [_,  r₂₆[4], _, 0]
+	VPERM T_0, R5_1, T_1, R5_1 // [_, 5r₂₆[1], _, 0]
+	VPERM T_0, R5_2, T_1, R5_2 // [_, 5r₂₆[2], _, 0]
+	VPERM T_0, R5_3, T_1, R5_3 // [_, 5r₂₆[3], _, 0]
+	VPERM T_0, R5_4, T_1, R5_4 // [_, 5r₂₆[4], _, 0]
+
+	// Set the value of lane 1 to be 1.
+	VLEIF $3, $1, R_0 // [_,  r₂₆[0], _, 1]
+
+	MOVD $0, R3
+	BR   multiply
diff --git a/vendor/golang.org/x/crypto/ssh/buffer.go b/vendor/golang.org/x/crypto/ssh/buffer.go
new file mode 100644
index 000000000..1ab07d078
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/buffer.go
@@ -0,0 +1,97 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"io"
+	"sync"
+)
+
+// buffer provides a linked list buffer for data exchange
+// between producer and consumer. Theoretically the buffer is
+// of unlimited capacity as it does no allocation of its own.
+type buffer struct {
+	// protects concurrent access to head, tail and closed
+	*sync.Cond
+
+	head *element // the buffer that will be read first
+	tail *element // the buffer that will be read last
+
+	closed bool
+}
+
+// An element represents a single link in a linked list.
+type element struct {
+	buf  []byte
+	next *element
+}
+
+// newBuffer returns an empty buffer that is not closed.
+func newBuffer() *buffer {
+	e := new(element)
+	b := &buffer{
+		Cond: newCond(),
+		head: e,
+		tail: e,
+	}
+	return b
+}
+
+// write makes buf available for Read to receive.
+// buf must not be modified after the call to write.
+func (b *buffer) write(buf []byte) {
+	b.Cond.L.Lock()
+	e := &element{buf: buf}
+	b.tail.next = e
+	b.tail = e
+	b.Cond.Signal()
+	b.Cond.L.Unlock()
+}
+
+// eof closes the buffer. Reads from the buffer once all
+// the data has been consumed will receive io.EOF.
+func (b *buffer) eof() {
+	b.Cond.L.Lock()
+	b.closed = true
+	b.Cond.Signal()
+	b.Cond.L.Unlock()
+}
+
+// Read reads data from the internal buffer in buf.  Reads will block
+// if no data is available, or until the buffer is closed.
+func (b *buffer) Read(buf []byte) (n int, err error) {
+	b.Cond.L.Lock()
+	defer b.Cond.L.Unlock()
+
+	for len(buf) > 0 {
+		// if there is data in b.head, copy it
+		if len(b.head.buf) > 0 {
+			r := copy(buf, b.head.buf)
+			buf, b.head.buf = buf[r:], b.head.buf[r:]
+			n += r
+			continue
+		}
+		// if there is a next buffer, make it the head
+		if len(b.head.buf) == 0 && b.head != b.tail {
+			b.head = b.head.next
+			continue
+		}
+
+		// if at least one byte has been copied, return
+		if n > 0 {
+			break
+		}
+
+		// if nothing was read, and there is nothing outstanding
+		// check to see if the buffer is closed.
+		if b.closed {
+			err = io.EOF
+			break
+		}
+		// out of buffers, wait for producer
+		b.Cond.Wait()
+	}
+	return
+}
diff --git a/vendor/golang.org/x/crypto/ssh/certs.go b/vendor/golang.org/x/crypto/ssh/certs.go
new file mode 100644
index 000000000..27d0e14aa
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/certs.go
@@ -0,0 +1,611 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"sort"
+	"time"
+)
+
+// Certificate algorithm names from [PROTOCOL.certkeys]. These values can appear
+// in Certificate.Type, PublicKey.Type, and ClientConfig.HostKeyAlgorithms.
+// Unlike key algorithm names, these are not passed to AlgorithmSigner nor
+// returned by MultiAlgorithmSigner and don't appear in the Signature.Format
+// field.
+const (
+	CertAlgoRSAv01        = "ssh-rsa-cert-v01@openssh.com"
+	CertAlgoDSAv01        = "ssh-dss-cert-v01@openssh.com"
+	CertAlgoECDSA256v01   = "ecdsa-sha2-nistp256-cert-v01@openssh.com"
+	CertAlgoECDSA384v01   = "ecdsa-sha2-nistp384-cert-v01@openssh.com"
+	CertAlgoECDSA521v01   = "ecdsa-sha2-nistp521-cert-v01@openssh.com"
+	CertAlgoSKECDSA256v01 = "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com"
+	CertAlgoED25519v01    = "ssh-ed25519-cert-v01@openssh.com"
+	CertAlgoSKED25519v01  = "sk-ssh-ed25519-cert-v01@openssh.com"
+
+	// CertAlgoRSASHA256v01 and CertAlgoRSASHA512v01 can't appear as a
+	// Certificate.Type (or PublicKey.Type), but only in
+	// ClientConfig.HostKeyAlgorithms.
+	CertAlgoRSASHA256v01 = "rsa-sha2-256-cert-v01@openssh.com"
+	CertAlgoRSASHA512v01 = "rsa-sha2-512-cert-v01@openssh.com"
+)
+
+const (
+	// Deprecated: use CertAlgoRSAv01.
+	CertSigAlgoRSAv01 = CertAlgoRSAv01
+	// Deprecated: use CertAlgoRSASHA256v01.
+	CertSigAlgoRSASHA2256v01 = CertAlgoRSASHA256v01
+	// Deprecated: use CertAlgoRSASHA512v01.
+	CertSigAlgoRSASHA2512v01 = CertAlgoRSASHA512v01
+)
+
+// Certificate types distinguish between host and user
+// certificates. The values can be set in the CertType field of
+// Certificate.
+const (
+	UserCert = 1
+	HostCert = 2
+)
+
+// Signature represents a cryptographic signature.
+type Signature struct {
+	Format string
+	Blob   []byte
+	Rest   []byte `ssh:"rest"`
+}
+
+// CertTimeInfinity can be used for OpenSSHCertV01.ValidBefore to indicate that
+// a certificate does not expire.
+const CertTimeInfinity = 1<<64 - 1
+
+// An Certificate represents an OpenSSH certificate as defined in
+// [PROTOCOL.certkeys]?rev=1.8. The Certificate type implements the
+// PublicKey interface, so it can be unmarshaled using
+// ParsePublicKey.
+type Certificate struct {
+	Nonce           []byte
+	Key             PublicKey
+	Serial          uint64
+	CertType        uint32
+	KeyId           string
+	ValidPrincipals []string
+	ValidAfter      uint64
+	ValidBefore     uint64
+	Permissions
+	Reserved     []byte
+	SignatureKey PublicKey
+	Signature    *Signature
+}
+
+// genericCertData holds the key-independent part of the certificate data.
+// Overall, certificates contain an nonce, public key fields and
+// key-independent fields.
+type genericCertData struct {
+	Serial          uint64
+	CertType        uint32
+	KeyId           string
+	ValidPrincipals []byte
+	ValidAfter      uint64
+	ValidBefore     uint64
+	CriticalOptions []byte
+	Extensions      []byte
+	Reserved        []byte
+	SignatureKey    []byte
+	Signature       []byte
+}
+
+func marshalStringList(namelist []string) []byte {
+	var to []byte
+	for _, name := range namelist {
+		s := struct{ N string }{name}
+		to = append(to, Marshal(&s)...)
+	}
+	return to
+}
+
+type optionsTuple struct {
+	Key   string
+	Value []byte
+}
+
+type optionsTupleValue struct {
+	Value string
+}
+
+// serialize a map of critical options or extensions
+// issue #10569 - per [PROTOCOL.certkeys] and SSH implementation,
+// we need two length prefixes for a non-empty string value
+func marshalTuples(tups map[string]string) []byte {
+	keys := make([]string, 0, len(tups))
+	for key := range tups {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	var ret []byte
+	for _, key := range keys {
+		s := optionsTuple{Key: key}
+		if value := tups[key]; len(value) > 0 {
+			s.Value = Marshal(&optionsTupleValue{value})
+		}
+		ret = append(ret, Marshal(&s)...)
+	}
+	return ret
+}
+
+// issue #10569 - per [PROTOCOL.certkeys] and SSH implementation,
+// we need two length prefixes for a non-empty option value
+func parseTuples(in []byte) (map[string]string, error) {
+	tups := map[string]string{}
+	var lastKey string
+	var haveLastKey bool
+
+	for len(in) > 0 {
+		var key, val, extra []byte
+		var ok bool
+
+		if key, in, ok = parseString(in); !ok {
+			return nil, errShortRead
+		}
+		keyStr := string(key)
+		// according to [PROTOCOL.certkeys], the names must be in
+		// lexical order.
+		if haveLastKey && keyStr <= lastKey {
+			return nil, fmt.Errorf("ssh: certificate options are not in lexical order")
+		}
+		lastKey, haveLastKey = keyStr, true
+		// the next field is a data field, which if non-empty has a string embedded
+		if val, in, ok = parseString(in); !ok {
+			return nil, errShortRead
+		}
+		if len(val) > 0 {
+			val, extra, ok = parseString(val)
+			if !ok {
+				return nil, errShortRead
+			}
+			if len(extra) > 0 {
+				return nil, fmt.Errorf("ssh: unexpected trailing data after certificate option value")
+			}
+			tups[keyStr] = string(val)
+		} else {
+			tups[keyStr] = ""
+		}
+	}
+	return tups, nil
+}
+
+func parseCert(in []byte, privAlgo string) (*Certificate, error) {
+	nonce, rest, ok := parseString(in)
+	if !ok {
+		return nil, errShortRead
+	}
+
+	key, rest, err := parsePubKey(rest, privAlgo)
+	if err != nil {
+		return nil, err
+	}
+
+	var g genericCertData
+	if err := Unmarshal(rest, &g); err != nil {
+		return nil, err
+	}
+
+	c := &Certificate{
+		Nonce:       nonce,
+		Key:         key,
+		Serial:      g.Serial,
+		CertType:    g.CertType,
+		KeyId:       g.KeyId,
+		ValidAfter:  g.ValidAfter,
+		ValidBefore: g.ValidBefore,
+	}
+
+	for principals := g.ValidPrincipals; len(principals) > 0; {
+		principal, rest, ok := parseString(principals)
+		if !ok {
+			return nil, errShortRead
+		}
+		c.ValidPrincipals = append(c.ValidPrincipals, string(principal))
+		principals = rest
+	}
+
+	c.CriticalOptions, err = parseTuples(g.CriticalOptions)
+	if err != nil {
+		return nil, err
+	}
+	c.Extensions, err = parseTuples(g.Extensions)
+	if err != nil {
+		return nil, err
+	}
+	c.Reserved = g.Reserved
+	k, err := ParsePublicKey(g.SignatureKey)
+	if err != nil {
+		return nil, err
+	}
+
+	c.SignatureKey = k
+	c.Signature, rest, ok = parseSignatureBody(g.Signature)
+	if !ok || len(rest) > 0 {
+		return nil, errors.New("ssh: signature parse error")
+	}
+
+	return c, nil
+}
+
+type openSSHCertSigner struct {
+	pub    *Certificate
+	signer Signer
+}
+
+type algorithmOpenSSHCertSigner struct {
+	*openSSHCertSigner
+	algorithmSigner AlgorithmSigner
+}
+
+// NewCertSigner returns a Signer that signs with the given Certificate, whose
+// private key is held by signer. It returns an error if the public key in cert
+// doesn't match the key used by signer.
+func NewCertSigner(cert *Certificate, signer Signer) (Signer, error) {
+	if !bytes.Equal(cert.Key.Marshal(), signer.PublicKey().Marshal()) {
+		return nil, errors.New("ssh: signer and cert have different public key")
+	}
+
+	switch s := signer.(type) {
+	case MultiAlgorithmSigner:
+		return &multiAlgorithmSigner{
+			AlgorithmSigner: &algorithmOpenSSHCertSigner{
+				&openSSHCertSigner{cert, signer}, s},
+			supportedAlgorithms: s.Algorithms(),
+		}, nil
+	case AlgorithmSigner:
+		return &algorithmOpenSSHCertSigner{
+			&openSSHCertSigner{cert, signer}, s}, nil
+	default:
+		return &openSSHCertSigner{cert, signer}, nil
+	}
+}
+
+func (s *openSSHCertSigner) Sign(rand io.Reader, data []byte) (*Signature, error) {
+	return s.signer.Sign(rand, data)
+}
+
+func (s *openSSHCertSigner) PublicKey() PublicKey {
+	return s.pub
+}
+
+func (s *algorithmOpenSSHCertSigner) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
+	return s.algorithmSigner.SignWithAlgorithm(rand, data, algorithm)
+}
+
+const sourceAddressCriticalOption = "source-address"
+
+// CertChecker does the work of verifying a certificate. Its methods
+// can be plugged into ClientConfig.HostKeyCallback and
+// ServerConfig.PublicKeyCallback. For the CertChecker to work,
+// minimally, the IsAuthority callback should be set.
+type CertChecker struct {
+	// SupportedCriticalOptions lists the CriticalOptions that the
+	// server application layer understands. These are only used
+	// for user certificates.
+	SupportedCriticalOptions []string
+
+	// IsUserAuthority should return true if the key is recognized as an
+	// authority for the given user certificate. This allows for
+	// certificates to be signed by other certificates. This must be set
+	// if this CertChecker will be checking user certificates.
+	IsUserAuthority func(auth PublicKey) bool
+
+	// IsHostAuthority should report whether the key is recognized as
+	// an authority for this host. This allows for certificates to be
+	// signed by other keys, and for those other keys to only be valid
+	// signers for particular hostnames. This must be set if this
+	// CertChecker will be checking host certificates.
+	IsHostAuthority func(auth PublicKey, address string) bool
+
+	// Clock is used for verifying time stamps. If nil, time.Now
+	// is used.
+	Clock func() time.Time
+
+	// UserKeyFallback is called when CertChecker.Authenticate encounters a
+	// public key that is not a certificate. It must implement validation
+	// of user keys or else, if nil, all such keys are rejected.
+	UserKeyFallback func(conn ConnMetadata, key PublicKey) (*Permissions, error)
+
+	// HostKeyFallback is called when CertChecker.CheckHostKey encounters a
+	// public key that is not a certificate. It must implement host key
+	// validation or else, if nil, all such keys are rejected.
+	HostKeyFallback HostKeyCallback
+
+	// IsRevoked is called for each certificate so that revocation checking
+	// can be implemented. It should return true if the given certificate
+	// is revoked and false otherwise. If nil, no certificates are
+	// considered to have been revoked.
+	IsRevoked func(cert *Certificate) bool
+}
+
+// CheckHostKey checks a host key certificate. This method can be
+// plugged into ClientConfig.HostKeyCallback.
+func (c *CertChecker) CheckHostKey(addr string, remote net.Addr, key PublicKey) error {
+	cert, ok := key.(*Certificate)
+	if !ok {
+		if c.HostKeyFallback != nil {
+			return c.HostKeyFallback(addr, remote, key)
+		}
+		return errors.New("ssh: non-certificate host key")
+	}
+	if cert.CertType != HostCert {
+		return fmt.Errorf("ssh: certificate presented as a host key has type %d", cert.CertType)
+	}
+	if !c.IsHostAuthority(cert.SignatureKey, addr) {
+		return fmt.Errorf("ssh: no authorities for hostname: %v", addr)
+	}
+
+	hostname, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return err
+	}
+
+	// Pass hostname only as principal for host certificates (consistent with OpenSSH)
+	return c.CheckCert(hostname, cert)
+}
+
+// Authenticate checks a user certificate. Authenticate can be used as
+// a value for ServerConfig.PublicKeyCallback.
+func (c *CertChecker) Authenticate(conn ConnMetadata, pubKey PublicKey) (*Permissions, error) {
+	cert, ok := pubKey.(*Certificate)
+	if !ok {
+		if c.UserKeyFallback != nil {
+			return c.UserKeyFallback(conn, pubKey)
+		}
+		return nil, errors.New("ssh: normal key pairs not accepted")
+	}
+
+	if cert.CertType != UserCert {
+		return nil, fmt.Errorf("ssh: cert has type %d", cert.CertType)
+	}
+	if !c.IsUserAuthority(cert.SignatureKey) {
+		return nil, fmt.Errorf("ssh: certificate signed by unrecognized authority")
+	}
+
+	if err := c.CheckCert(conn.User(), cert); err != nil {
+		return nil, err
+	}
+
+	return &cert.Permissions, nil
+}
+
+// CheckCert checks CriticalOptions, ValidPrincipals, revocation, timestamp and
+// the signature of the certificate.
+func (c *CertChecker) CheckCert(principal string, cert *Certificate) error {
+	if c.IsRevoked != nil && c.IsRevoked(cert) {
+		return fmt.Errorf("ssh: certificate serial %d revoked", cert.Serial)
+	}
+
+	for opt := range cert.CriticalOptions {
+		// sourceAddressCriticalOption will be enforced by
+		// serverAuthenticate
+		if opt == sourceAddressCriticalOption {
+			continue
+		}
+
+		found := false
+		for _, supp := range c.SupportedCriticalOptions {
+			if supp == opt {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return fmt.Errorf("ssh: unsupported critical option %q in certificate", opt)
+		}
+	}
+
+	if len(cert.ValidPrincipals) > 0 {
+		// By default, certs are valid for all users/hosts.
+		found := false
+		for _, p := range cert.ValidPrincipals {
+			if p == principal {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return fmt.Errorf("ssh: principal %q not in the set of valid principals for given certificate: %q", principal, cert.ValidPrincipals)
+		}
+	}
+
+	clock := c.Clock
+	if clock == nil {
+		clock = time.Now
+	}
+
+	unixNow := clock().Unix()
+	if after := int64(cert.ValidAfter); after < 0 || unixNow < int64(cert.ValidAfter) {
+		return fmt.Errorf("ssh: cert is not yet valid")
+	}
+	if before := int64(cert.ValidBefore); cert.ValidBefore != uint64(CertTimeInfinity) && (unixNow >= before || before < 0) {
+		return fmt.Errorf("ssh: cert has expired")
+	}
+	if err := cert.SignatureKey.Verify(cert.bytesForSigning(), cert.Signature); err != nil {
+		return fmt.Errorf("ssh: certificate signature does not verify")
+	}
+
+	return nil
+}
+
+// SignCert signs the certificate with an authority, setting the Nonce,
+// SignatureKey, and Signature fields. If the authority implements the
+// MultiAlgorithmSigner interface the first algorithm in the list is used. This
+// is useful if you want to sign with a specific algorithm.
+func (c *Certificate) SignCert(rand io.Reader, authority Signer) error {
+	c.Nonce = make([]byte, 32)
+	if _, err := io.ReadFull(rand, c.Nonce); err != nil {
+		return err
+	}
+	c.SignatureKey = authority.PublicKey()
+
+	if v, ok := authority.(MultiAlgorithmSigner); ok {
+		if len(v.Algorithms()) == 0 {
+			return errors.New("the provided authority has no signature algorithm")
+		}
+		// Use the first algorithm in the list.
+		sig, err := v.SignWithAlgorithm(rand, c.bytesForSigning(), v.Algorithms()[0])
+		if err != nil {
+			return err
+		}
+		c.Signature = sig
+		return nil
+	} else if v, ok := authority.(AlgorithmSigner); ok && v.PublicKey().Type() == KeyAlgoRSA {
+		// Default to KeyAlgoRSASHA512 for ssh-rsa signers.
+		// TODO: consider using KeyAlgoRSASHA256 as default.
+		sig, err := v.SignWithAlgorithm(rand, c.bytesForSigning(), KeyAlgoRSASHA512)
+		if err != nil {
+			return err
+		}
+		c.Signature = sig
+		return nil
+	}
+
+	sig, err := authority.Sign(rand, c.bytesForSigning())
+	if err != nil {
+		return err
+	}
+	c.Signature = sig
+	return nil
+}
+
+// certKeyAlgoNames is a mapping from known certificate algorithm names to the
+// corresponding public key signature algorithm.
+//
+// This map must be kept in sync with the one in agent/client.go.
+var certKeyAlgoNames = map[string]string{
+	CertAlgoRSAv01:        KeyAlgoRSA,
+	CertAlgoRSASHA256v01:  KeyAlgoRSASHA256,
+	CertAlgoRSASHA512v01:  KeyAlgoRSASHA512,
+	CertAlgoDSAv01:        KeyAlgoDSA,
+	CertAlgoECDSA256v01:   KeyAlgoECDSA256,
+	CertAlgoECDSA384v01:   KeyAlgoECDSA384,
+	CertAlgoECDSA521v01:   KeyAlgoECDSA521,
+	CertAlgoSKECDSA256v01: KeyAlgoSKECDSA256,
+	CertAlgoED25519v01:    KeyAlgoED25519,
+	CertAlgoSKED25519v01:  KeyAlgoSKED25519,
+}
+
+// underlyingAlgo returns the signature algorithm associated with algo (which is
+// an advertised or negotiated public key or host key algorithm). These are
+// usually the same, except for certificate algorithms.
+func underlyingAlgo(algo string) string {
+	if a, ok := certKeyAlgoNames[algo]; ok {
+		return a
+	}
+	return algo
+}
+
+// certificateAlgo returns the certificate algorithms that uses the provided
+// underlying signature algorithm.
+func certificateAlgo(algo string) (certAlgo string, ok bool) {
+	for certName, algoName := range certKeyAlgoNames {
+		if algoName == algo {
+			return certName, true
+		}
+	}
+	return "", false
+}
+
+func (cert *Certificate) bytesForSigning() []byte {
+	c2 := *cert
+	c2.Signature = nil
+	out := c2.Marshal()
+	// Drop trailing signature length.
+	return out[:len(out)-4]
+}
+
+// Marshal serializes c into OpenSSH's wire format. It is part of the
+// PublicKey interface.
+func (c *Certificate) Marshal() []byte {
+	generic := genericCertData{
+		Serial:          c.Serial,
+		CertType:        c.CertType,
+		KeyId:           c.KeyId,
+		ValidPrincipals: marshalStringList(c.ValidPrincipals),
+		ValidAfter:      uint64(c.ValidAfter),
+		ValidBefore:     uint64(c.ValidBefore),
+		CriticalOptions: marshalTuples(c.CriticalOptions),
+		Extensions:      marshalTuples(c.Extensions),
+		Reserved:        c.Reserved,
+		SignatureKey:    c.SignatureKey.Marshal(),
+	}
+	if c.Signature != nil {
+		generic.Signature = Marshal(c.Signature)
+	}
+	genericBytes := Marshal(&generic)
+	keyBytes := c.Key.Marshal()
+	_, keyBytes, _ = parseString(keyBytes)
+	prefix := Marshal(&struct {
+		Name  string
+		Nonce []byte
+		Key   []byte `ssh:"rest"`
+	}{c.Type(), c.Nonce, keyBytes})
+
+	result := make([]byte, 0, len(prefix)+len(genericBytes))
+	result = append(result, prefix...)
+	result = append(result, genericBytes...)
+	return result
+}
+
+// Type returns the certificate algorithm name. It is part of the PublicKey interface.
+func (c *Certificate) Type() string {
+	certName, ok := certificateAlgo(c.Key.Type())
+	if !ok {
+		panic("unknown certificate type for key type " + c.Key.Type())
+	}
+	return certName
+}
+
+// Verify verifies a signature against the certificate's public
+// key. It is part of the PublicKey interface.
+func (c *Certificate) Verify(data []byte, sig *Signature) error {
+	return c.Key.Verify(data, sig)
+}
+
+func parseSignatureBody(in []byte) (out *Signature, rest []byte, ok bool) {
+	format, in, ok := parseString(in)
+	if !ok {
+		return
+	}
+
+	out = &Signature{
+		Format: string(format),
+	}
+
+	if out.Blob, in, ok = parseString(in); !ok {
+		return
+	}
+
+	switch out.Format {
+	case KeyAlgoSKECDSA256, CertAlgoSKECDSA256v01, KeyAlgoSKED25519, CertAlgoSKED25519v01:
+		out.Rest = in
+		return out, nil, ok
+	}
+
+	return out, in, ok
+}
+
+func parseSignature(in []byte) (out *Signature, rest []byte, ok bool) {
+	sigBytes, rest, ok := parseString(in)
+	if !ok {
+		return
+	}
+
+	out, trailing, ok := parseSignatureBody(sigBytes)
+	if !ok || len(trailing) > 0 {
+		return nil, nil, false
+	}
+	return
+}
diff --git a/vendor/golang.org/x/crypto/ssh/channel.go b/vendor/golang.org/x/crypto/ssh/channel.go
new file mode 100644
index 000000000..cc0bb7ab6
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/channel.go
@@ -0,0 +1,645 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"sync"
+)
+
+const (
+	minPacketLength = 9
+	// channelMaxPacket contains the maximum number of bytes that will be
+	// sent in a single packet. As per RFC 4253, section 6.1, 32k is also
+	// the minimum.
+	channelMaxPacket = 1 << 15
+	// We follow OpenSSH here.
+	channelWindowSize = 64 * channelMaxPacket
+)
+
+// NewChannel represents an incoming request to a channel. It must either be
+// accepted for use by calling Accept, or rejected by calling Reject.
+type NewChannel interface {
+	// Accept accepts the channel creation request. It returns the Channel
+	// and a Go channel containing SSH requests. The Go channel must be
+	// serviced otherwise the Channel will hang.
+	Accept() (Channel, <-chan *Request, error)
+
+	// Reject rejects the channel creation request. After calling
+	// this, no other methods on the Channel may be called.
+	Reject(reason RejectionReason, message string) error
+
+	// ChannelType returns the type of the channel, as supplied by the
+	// client.
+	ChannelType() string
+
+	// ExtraData returns the arbitrary payload for this channel, as supplied
+	// by the client. This data is specific to the channel type.
+	ExtraData() []byte
+}
+
+// A Channel is an ordered, reliable, flow-controlled, duplex stream
+// that is multiplexed over an SSH connection.
+type Channel interface {
+	// Read reads up to len(data) bytes from the channel.
+	Read(data []byte) (int, error)
+
+	// Write writes len(data) bytes to the channel.
+	Write(data []byte) (int, error)
+
+	// Close signals end of channel use. No data may be sent after this
+	// call.
+	Close() error
+
+	// CloseWrite signals the end of sending in-band
+	// data. Requests may still be sent, and the other side may
+	// still send data
+	CloseWrite() error
+
+	// SendRequest sends a channel request.  If wantReply is true,
+	// it will wait for a reply and return the result as a
+	// boolean, otherwise the return value will be false. Channel
+	// requests are out-of-band messages so they may be sent even
+	// if the data stream is closed or blocked by flow control.
+	// If the channel is closed before a reply is returned, io.EOF
+	// is returned.
+	SendRequest(name string, wantReply bool, payload []byte) (bool, error)
+
+	// Stderr returns an io.ReadWriter that writes to this channel
+	// with the extended data type set to stderr. Stderr may
+	// safely be read and written from a different goroutine than
+	// Read and Write respectively.
+	Stderr() io.ReadWriter
+}
+
+// Request is a request sent outside of the normal stream of
+// data. Requests can either be specific to an SSH channel, or they
+// can be global.
+type Request struct {
+	Type      string
+	WantReply bool
+	Payload   []byte
+
+	ch  *channel
+	mux *mux
+}
+
+// Reply sends a response to a request. It must be called for all requests
+// where WantReply is true and is a no-op otherwise. The payload argument is
+// ignored for replies to channel-specific requests.
+func (r *Request) Reply(ok bool, payload []byte) error {
+	if !r.WantReply {
+		return nil
+	}
+
+	if r.ch == nil {
+		return r.mux.ackRequest(ok, payload)
+	}
+
+	return r.ch.ackRequest(ok)
+}
+
+// RejectionReason is an enumeration used when rejecting channel creation
+// requests. See RFC 4254, section 5.1.
+type RejectionReason uint32
+
+const (
+	Prohibited RejectionReason = iota + 1
+	ConnectionFailed
+	UnknownChannelType
+	ResourceShortage
+)
+
+// String converts the rejection reason to human readable form.
+func (r RejectionReason) String() string {
+	switch r {
+	case Prohibited:
+		return "administratively prohibited"
+	case ConnectionFailed:
+		return "connect failed"
+	case UnknownChannelType:
+		return "unknown channel type"
+	case ResourceShortage:
+		return "resource shortage"
+	}
+	return fmt.Sprintf("unknown reason %d", int(r))
+}
+
+func min(a uint32, b int) uint32 {
+	if a < uint32(b) {
+		return a
+	}
+	return uint32(b)
+}
+
+type channelDirection uint8
+
+const (
+	channelInbound channelDirection = iota
+	channelOutbound
+)
+
+// channel is an implementation of the Channel interface that works
+// with the mux class.
+type channel struct {
+	// R/O after creation
+	chanType          string
+	extraData         []byte
+	localId, remoteId uint32
+
+	// maxIncomingPayload and maxRemotePayload are the maximum
+	// payload sizes of normal and extended data packets for
+	// receiving and sending, respectively. The wire packet will
+	// be 9 or 13 bytes larger (excluding encryption overhead).
+	maxIncomingPayload uint32
+	maxRemotePayload   uint32
+
+	mux *mux
+
+	// decided is set to true if an accept or reject message has been sent
+	// (for outbound channels) or received (for inbound channels).
+	decided bool
+
+	// direction contains either channelOutbound, for channels created
+	// locally, or channelInbound, for channels created by the peer.
+	direction channelDirection
+
+	// Pending internal channel messages.
+	msg chan interface{}
+
+	// Since requests have no ID, there can be only one request
+	// with WantReply=true outstanding.  This lock is held by a
+	// goroutine that has such an outgoing request pending.
+	sentRequestMu sync.Mutex
+
+	incomingRequests chan *Request
+
+	sentEOF bool
+
+	// thread-safe data
+	remoteWin  window
+	pending    *buffer
+	extPending *buffer
+
+	// windowMu protects myWindow, the flow-control window, and myConsumed,
+	// the number of bytes consumed since we last increased myWindow
+	windowMu   sync.Mutex
+	myWindow   uint32
+	myConsumed uint32
+
+	// writeMu serializes calls to mux.conn.writePacket() and
+	// protects sentClose and packetPool. This mutex must be
+	// different from windowMu, as writePacket can block if there
+	// is a key exchange pending.
+	writeMu   sync.Mutex
+	sentClose bool
+
+	// packetPool has a buffer for each extended channel ID to
+	// save allocations during writes.
+	packetPool map[uint32][]byte
+}
+
+// writePacket sends a packet. If the packet is a channel close, it updates
+// sentClose. This method takes the lock c.writeMu.
+func (ch *channel) writePacket(packet []byte) error {
+	ch.writeMu.Lock()
+	if ch.sentClose {
+		ch.writeMu.Unlock()
+		return io.EOF
+	}
+	ch.sentClose = (packet[0] == msgChannelClose)
+	err := ch.mux.conn.writePacket(packet)
+	ch.writeMu.Unlock()
+	return err
+}
+
+func (ch *channel) sendMessage(msg interface{}) error {
+	if debugMux {
+		log.Printf("send(%d): %#v", ch.mux.chanList.offset, msg)
+	}
+
+	p := Marshal(msg)
+	binary.BigEndian.PutUint32(p[1:], ch.remoteId)
+	return ch.writePacket(p)
+}
+
+// WriteExtended writes data to a specific extended stream. These streams are
+// used, for example, for stderr.
+func (ch *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err error) {
+	if ch.sentEOF {
+		return 0, io.EOF
+	}
+	// 1 byte message type, 4 bytes remoteId, 4 bytes data length
+	opCode := byte(msgChannelData)
+	headerLength := uint32(9)
+	if extendedCode > 0 {
+		headerLength += 4
+		opCode = msgChannelExtendedData
+	}
+
+	ch.writeMu.Lock()
+	packet := ch.packetPool[extendedCode]
+	// We don't remove the buffer from packetPool, so
+	// WriteExtended calls from different goroutines will be
+	// flagged as errors by the race detector.
+	ch.writeMu.Unlock()
+
+	for len(data) > 0 {
+		space := min(ch.maxRemotePayload, len(data))
+		if space, err = ch.remoteWin.reserve(space); err != nil {
+			return n, err
+		}
+		if want := headerLength + space; uint32(cap(packet)) < want {
+			packet = make([]byte, want)
+		} else {
+			packet = packet[:want]
+		}
+
+		todo := data[:space]
+
+		packet[0] = opCode
+		binary.BigEndian.PutUint32(packet[1:], ch.remoteId)
+		if extendedCode > 0 {
+			binary.BigEndian.PutUint32(packet[5:], uint32(extendedCode))
+		}
+		binary.BigEndian.PutUint32(packet[headerLength-4:], uint32(len(todo)))
+		copy(packet[headerLength:], todo)
+		if err = ch.writePacket(packet); err != nil {
+			return n, err
+		}
+
+		n += len(todo)
+		data = data[len(todo):]
+	}
+
+	ch.writeMu.Lock()
+	ch.packetPool[extendedCode] = packet
+	ch.writeMu.Unlock()
+
+	return n, err
+}
+
+func (ch *channel) handleData(packet []byte) error {
+	headerLen := 9
+	isExtendedData := packet[0] == msgChannelExtendedData
+	if isExtendedData {
+		headerLen = 13
+	}
+	if len(packet) < headerLen {
+		// malformed data packet
+		return parseError(packet[0])
+	}
+
+	var extended uint32
+	if isExtendedData {
+		extended = binary.BigEndian.Uint32(packet[5:])
+	}
+
+	length := binary.BigEndian.Uint32(packet[headerLen-4 : headerLen])
+	if length == 0 {
+		return nil
+	}
+	if length > ch.maxIncomingPayload {
+		// TODO(hanwen): should send Disconnect?
+		return errors.New("ssh: incoming packet exceeds maximum payload size")
+	}
+
+	data := packet[headerLen:]
+	if length != uint32(len(data)) {
+		return errors.New("ssh: wrong packet length")
+	}
+
+	ch.windowMu.Lock()
+	if ch.myWindow < length {
+		ch.windowMu.Unlock()
+		// TODO(hanwen): should send Disconnect with reason?
+		return errors.New("ssh: remote side wrote too much")
+	}
+	ch.myWindow -= length
+	ch.windowMu.Unlock()
+
+	if extended == 1 {
+		ch.extPending.write(data)
+	} else if extended > 0 {
+		// discard other extended data.
+	} else {
+		ch.pending.write(data)
+	}
+	return nil
+}
+
+func (c *channel) adjustWindow(adj uint32) error {
+	c.windowMu.Lock()
+	// Since myConsumed and myWindow are managed on our side, and can never
+	// exceed the initial window setting, we don't worry about overflow.
+	c.myConsumed += adj
+	var sendAdj uint32
+	if (channelWindowSize-c.myWindow > 3*c.maxIncomingPayload) ||
+		(c.myWindow < channelWindowSize/2) {
+		sendAdj = c.myConsumed
+		c.myConsumed = 0
+		c.myWindow += sendAdj
+	}
+	c.windowMu.Unlock()
+	if sendAdj == 0 {
+		return nil
+	}
+	return c.sendMessage(windowAdjustMsg{
+		AdditionalBytes: sendAdj,
+	})
+}
+
+func (c *channel) ReadExtended(data []byte, extended uint32) (n int, err error) {
+	switch extended {
+	case 1:
+		n, err = c.extPending.Read(data)
+	case 0:
+		n, err = c.pending.Read(data)
+	default:
+		return 0, fmt.Errorf("ssh: extended code %d unimplemented", extended)
+	}
+
+	if n > 0 {
+		err = c.adjustWindow(uint32(n))
+		// sendWindowAdjust can return io.EOF if the remote
+		// peer has closed the connection, however we want to
+		// defer forwarding io.EOF to the caller of Read until
+		// the buffer has been drained.
+		if n > 0 && err == io.EOF {
+			err = nil
+		}
+	}
+
+	return n, err
+}
+
+func (c *channel) close() {
+	c.pending.eof()
+	c.extPending.eof()
+	close(c.msg)
+	close(c.incomingRequests)
+	c.writeMu.Lock()
+	// This is not necessary for a normal channel teardown, but if
+	// there was another error, it is.
+	c.sentClose = true
+	c.writeMu.Unlock()
+	// Unblock writers.
+	c.remoteWin.close()
+}
+
+// responseMessageReceived is called when a success or failure message is
+// received on a channel to check that such a message is reasonable for the
+// given channel.
+func (ch *channel) responseMessageReceived() error {
+	if ch.direction == channelInbound {
+		return errors.New("ssh: channel response message received on inbound channel")
+	}
+	if ch.decided {
+		return errors.New("ssh: duplicate response received for channel")
+	}
+	ch.decided = true
+	return nil
+}
+
+func (ch *channel) handlePacket(packet []byte) error {
+	switch packet[0] {
+	case msgChannelData, msgChannelExtendedData:
+		return ch.handleData(packet)
+	case msgChannelClose:
+		ch.sendMessage(channelCloseMsg{PeersID: ch.remoteId})
+		ch.mux.chanList.remove(ch.localId)
+		ch.close()
+		return nil
+	case msgChannelEOF:
+		// RFC 4254 is mute on how EOF affects dataExt messages but
+		// it is logical to signal EOF at the same time.
+		ch.extPending.eof()
+		ch.pending.eof()
+		return nil
+	}
+
+	decoded, err := decode(packet)
+	if err != nil {
+		return err
+	}
+
+	switch msg := decoded.(type) {
+	case *channelOpenFailureMsg:
+		if err := ch.responseMessageReceived(); err != nil {
+			return err
+		}
+		ch.mux.chanList.remove(msg.PeersID)
+		ch.msg <- msg
+	case *channelOpenConfirmMsg:
+		if err := ch.responseMessageReceived(); err != nil {
+			return err
+		}
+		if msg.MaxPacketSize < minPacketLength || msg.MaxPacketSize > 1<<31 {
+			return fmt.Errorf("ssh: invalid MaxPacketSize %d from peer", msg.MaxPacketSize)
+		}
+		ch.remoteId = msg.MyID
+		ch.maxRemotePayload = msg.MaxPacketSize
+		ch.remoteWin.add(msg.MyWindow)
+		ch.msg <- msg
+	case *windowAdjustMsg:
+		if !ch.remoteWin.add(msg.AdditionalBytes) {
+			return fmt.Errorf("ssh: invalid window update for %d bytes", msg.AdditionalBytes)
+		}
+	case *channelRequestMsg:
+		req := Request{
+			Type:      msg.Request,
+			WantReply: msg.WantReply,
+			Payload:   msg.RequestSpecificData,
+			ch:        ch,
+		}
+
+		ch.incomingRequests <- &req
+	default:
+		ch.msg <- msg
+	}
+	return nil
+}
+
+func (m *mux) newChannel(chanType string, direction channelDirection, extraData []byte) *channel {
+	ch := &channel{
+		remoteWin:        window{Cond: newCond()},
+		myWindow:         channelWindowSize,
+		pending:          newBuffer(),
+		extPending:       newBuffer(),
+		direction:        direction,
+		incomingRequests: make(chan *Request, chanSize),
+		msg:              make(chan interface{}, chanSize),
+		chanType:         chanType,
+		extraData:        extraData,
+		mux:              m,
+		packetPool:       make(map[uint32][]byte),
+	}
+	ch.localId = m.chanList.add(ch)
+	return ch
+}
+
+var errUndecided = errors.New("ssh: must Accept or Reject channel")
+var errDecidedAlready = errors.New("ssh: can call Accept or Reject only once")
+
+type extChannel struct {
+	code uint32
+	ch   *channel
+}
+
+func (e *extChannel) Write(data []byte) (n int, err error) {
+	return e.ch.WriteExtended(data, e.code)
+}
+
+func (e *extChannel) Read(data []byte) (n int, err error) {
+	return e.ch.ReadExtended(data, e.code)
+}
+
+func (ch *channel) Accept() (Channel, <-chan *Request, error) {
+	if ch.decided {
+		return nil, nil, errDecidedAlready
+	}
+	ch.maxIncomingPayload = channelMaxPacket
+	confirm := channelOpenConfirmMsg{
+		PeersID:       ch.remoteId,
+		MyID:          ch.localId,
+		MyWindow:      ch.myWindow,
+		MaxPacketSize: ch.maxIncomingPayload,
+	}
+	ch.decided = true
+	if err := ch.sendMessage(confirm); err != nil {
+		return nil, nil, err
+	}
+
+	return ch, ch.incomingRequests, nil
+}
+
+func (ch *channel) Reject(reason RejectionReason, message string) error {
+	if ch.decided {
+		return errDecidedAlready
+	}
+	reject := channelOpenFailureMsg{
+		PeersID:  ch.remoteId,
+		Reason:   reason,
+		Message:  message,
+		Language: "en",
+	}
+	ch.decided = true
+	return ch.sendMessage(reject)
+}
+
+func (ch *channel) Read(data []byte) (int, error) {
+	if !ch.decided {
+		return 0, errUndecided
+	}
+	return ch.ReadExtended(data, 0)
+}
+
+func (ch *channel) Write(data []byte) (int, error) {
+	if !ch.decided {
+		return 0, errUndecided
+	}
+	return ch.WriteExtended(data, 0)
+}
+
+func (ch *channel) CloseWrite() error {
+	if !ch.decided {
+		return errUndecided
+	}
+	ch.sentEOF = true
+	return ch.sendMessage(channelEOFMsg{
+		PeersID: ch.remoteId})
+}
+
+func (ch *channel) Close() error {
+	if !ch.decided {
+		return errUndecided
+	}
+
+	return ch.sendMessage(channelCloseMsg{
+		PeersID: ch.remoteId})
+}
+
+// Extended returns an io.ReadWriter that sends and receives data on the given,
+// SSH extended stream. Such streams are used, for example, for stderr.
+func (ch *channel) Extended(code uint32) io.ReadWriter {
+	if !ch.decided {
+		return nil
+	}
+	return &extChannel{code, ch}
+}
+
+func (ch *channel) Stderr() io.ReadWriter {
+	return ch.Extended(1)
+}
+
+func (ch *channel) SendRequest(name string, wantReply bool, payload []byte) (bool, error) {
+	if !ch.decided {
+		return false, errUndecided
+	}
+
+	if wantReply {
+		ch.sentRequestMu.Lock()
+		defer ch.sentRequestMu.Unlock()
+	}
+
+	msg := channelRequestMsg{
+		PeersID:             ch.remoteId,
+		Request:             name,
+		WantReply:           wantReply,
+		RequestSpecificData: payload,
+	}
+
+	if err := ch.sendMessage(msg); err != nil {
+		return false, err
+	}
+
+	if wantReply {
+		m, ok := (<-ch.msg)
+		if !ok {
+			return false, io.EOF
+		}
+		switch m.(type) {
+		case *channelRequestFailureMsg:
+			return false, nil
+		case *channelRequestSuccessMsg:
+			return true, nil
+		default:
+			return false, fmt.Errorf("ssh: unexpected response to channel request: %#v", m)
+		}
+	}
+
+	return false, nil
+}
+
+// ackRequest either sends an ack or nack to the channel request.
+func (ch *channel) ackRequest(ok bool) error {
+	if !ch.decided {
+		return errUndecided
+	}
+
+	var msg interface{}
+	if !ok {
+		msg = channelRequestFailureMsg{
+			PeersID: ch.remoteId,
+		}
+	} else {
+		msg = channelRequestSuccessMsg{
+			PeersID: ch.remoteId,
+		}
+	}
+	return ch.sendMessage(msg)
+}
+
+func (ch *channel) ChannelType() string {
+	return ch.chanType
+}
+
+func (ch *channel) ExtraData() []byte {
+	return ch.extraData
+}
diff --git a/vendor/golang.org/x/crypto/ssh/cipher.go b/vendor/golang.org/x/crypto/ssh/cipher.go
new file mode 100644
index 000000000..741e984f3
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/cipher.go
@@ -0,0 +1,789 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/des"
+	"crypto/rc4"
+	"crypto/subtle"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"hash"
+	"io"
+
+	"golang.org/x/crypto/chacha20"
+	"golang.org/x/crypto/internal/poly1305"
+)
+
+const (
+	packetSizeMultiple = 16 // TODO(huin) this should be determined by the cipher.
+
+	// RFC 4253 section 6.1 defines a minimum packet size of 32768 that implementations
+	// MUST be able to process (plus a few more kilobytes for padding and mac). The RFC
+	// indicates implementations SHOULD be able to handle larger packet sizes, but then
+	// waffles on about reasonable limits.
+	//
+	// OpenSSH caps their maxPacket at 256kB so we choose to do
+	// the same. maxPacket is also used to ensure that uint32
+	// length fields do not overflow, so it should remain well
+	// below 4G.
+	maxPacket = 256 * 1024
+)
+
+// noneCipher implements cipher.Stream and provides no encryption. It is used
+// by the transport before the first key-exchange.
+type noneCipher struct{}
+
+func (c noneCipher) XORKeyStream(dst, src []byte) {
+	copy(dst, src)
+}
+
+func newAESCTR(key, iv []byte) (cipher.Stream, error) {
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	return cipher.NewCTR(c, iv), nil
+}
+
+func newRC4(key, iv []byte) (cipher.Stream, error) {
+	return rc4.NewCipher(key)
+}
+
+type cipherMode struct {
+	keySize int
+	ivSize  int
+	create  func(key, iv []byte, macKey []byte, algs directionAlgorithms) (packetCipher, error)
+}
+
+func streamCipherMode(skip int, createFunc func(key, iv []byte) (cipher.Stream, error)) func(key, iv []byte, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	return func(key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+		stream, err := createFunc(key, iv)
+		if err != nil {
+			return nil, err
+		}
+
+		var streamDump []byte
+		if skip > 0 {
+			streamDump = make([]byte, 512)
+		}
+
+		for remainingToDump := skip; remainingToDump > 0; {
+			dumpThisTime := remainingToDump
+			if dumpThisTime > len(streamDump) {
+				dumpThisTime = len(streamDump)
+			}
+			stream.XORKeyStream(streamDump[:dumpThisTime], streamDump[:dumpThisTime])
+			remainingToDump -= dumpThisTime
+		}
+
+		mac := macModes[algs.MAC].new(macKey)
+		return &streamPacketCipher{
+			mac:       mac,
+			etm:       macModes[algs.MAC].etm,
+			macResult: make([]byte, mac.Size()),
+			cipher:    stream,
+		}, nil
+	}
+}
+
+// cipherModes documents properties of supported ciphers. Ciphers not included
+// are not supported and will not be negotiated, even if explicitly requested in
+// ClientConfig.Crypto.Ciphers.
+var cipherModes = map[string]*cipherMode{
+	// Ciphers from RFC 4344, which introduced many CTR-based ciphers. Algorithms
+	// are defined in the order specified in the RFC.
+	"aes128-ctr": {16, aes.BlockSize, streamCipherMode(0, newAESCTR)},
+	"aes192-ctr": {24, aes.BlockSize, streamCipherMode(0, newAESCTR)},
+	"aes256-ctr": {32, aes.BlockSize, streamCipherMode(0, newAESCTR)},
+
+	// Ciphers from RFC 4345, which introduces security-improved arcfour ciphers.
+	// They are defined in the order specified in the RFC.
+	"arcfour128": {16, 0, streamCipherMode(1536, newRC4)},
+	"arcfour256": {32, 0, streamCipherMode(1536, newRC4)},
+
+	// Cipher defined in RFC 4253, which describes SSH Transport Layer Protocol.
+	// Note that this cipher is not safe, as stated in RFC 4253: "Arcfour (and
+	// RC4) has problems with weak keys, and should be used with caution."
+	// RFC 4345 introduces improved versions of Arcfour.
+	"arcfour": {16, 0, streamCipherMode(0, newRC4)},
+
+	// AEAD ciphers
+	gcm128CipherID:     {16, 12, newGCMCipher},
+	gcm256CipherID:     {32, 12, newGCMCipher},
+	chacha20Poly1305ID: {64, 0, newChaCha20Cipher},
+
+	// CBC mode is insecure and so is not included in the default config.
+	// (See https://www.ieee-security.org/TC/SP2013/papers/4977a526.pdf). If absolutely
+	// needed, it's possible to specify a custom Config to enable it.
+	// You should expect that an active attacker can recover plaintext if
+	// you do.
+	aes128cbcID: {16, aes.BlockSize, newAESCBCCipher},
+
+	// 3des-cbc is insecure and is not included in the default
+	// config.
+	tripledescbcID: {24, des.BlockSize, newTripleDESCBCCipher},
+}
+
+// prefixLen is the length of the packet prefix that contains the packet length
+// and number of padding bytes.
+const prefixLen = 5
+
+// streamPacketCipher is a packetCipher using a stream cipher.
+type streamPacketCipher struct {
+	mac    hash.Hash
+	cipher cipher.Stream
+	etm    bool
+
+	// The following members are to avoid per-packet allocations.
+	prefix      [prefixLen]byte
+	seqNumBytes [4]byte
+	padding     [2 * packetSizeMultiple]byte
+	packetData  []byte
+	macResult   []byte
+}
+
+// readCipherPacket reads and decrypt a single packet from the reader argument.
+func (s *streamPacketCipher) readCipherPacket(seqNum uint32, r io.Reader) ([]byte, error) {
+	if _, err := io.ReadFull(r, s.prefix[:]); err != nil {
+		return nil, err
+	}
+
+	var encryptedPaddingLength [1]byte
+	if s.mac != nil && s.etm {
+		copy(encryptedPaddingLength[:], s.prefix[4:5])
+		s.cipher.XORKeyStream(s.prefix[4:5], s.prefix[4:5])
+	} else {
+		s.cipher.XORKeyStream(s.prefix[:], s.prefix[:])
+	}
+
+	length := binary.BigEndian.Uint32(s.prefix[0:4])
+	paddingLength := uint32(s.prefix[4])
+
+	var macSize uint32
+	if s.mac != nil {
+		s.mac.Reset()
+		binary.BigEndian.PutUint32(s.seqNumBytes[:], seqNum)
+		s.mac.Write(s.seqNumBytes[:])
+		if s.etm {
+			s.mac.Write(s.prefix[:4])
+			s.mac.Write(encryptedPaddingLength[:])
+		} else {
+			s.mac.Write(s.prefix[:])
+		}
+		macSize = uint32(s.mac.Size())
+	}
+
+	if length <= paddingLength+1 {
+		return nil, errors.New("ssh: invalid packet length, packet too small")
+	}
+
+	if length > maxPacket {
+		return nil, errors.New("ssh: invalid packet length, packet too large")
+	}
+
+	// the maxPacket check above ensures that length-1+macSize
+	// does not overflow.
+	if uint32(cap(s.packetData)) < length-1+macSize {
+		s.packetData = make([]byte, length-1+macSize)
+	} else {
+		s.packetData = s.packetData[:length-1+macSize]
+	}
+
+	if _, err := io.ReadFull(r, s.packetData); err != nil {
+		return nil, err
+	}
+	mac := s.packetData[length-1:]
+	data := s.packetData[:length-1]
+
+	if s.mac != nil && s.etm {
+		s.mac.Write(data)
+	}
+
+	s.cipher.XORKeyStream(data, data)
+
+	if s.mac != nil {
+		if !s.etm {
+			s.mac.Write(data)
+		}
+		s.macResult = s.mac.Sum(s.macResult[:0])
+		if subtle.ConstantTimeCompare(s.macResult, mac) != 1 {
+			return nil, errors.New("ssh: MAC failure")
+		}
+	}
+
+	return s.packetData[:length-paddingLength-1], nil
+}
+
+// writeCipherPacket encrypts and sends a packet of data to the writer argument
+func (s *streamPacketCipher) writeCipherPacket(seqNum uint32, w io.Writer, rand io.Reader, packet []byte) error {
+	if len(packet) > maxPacket {
+		return errors.New("ssh: packet too large")
+	}
+
+	aadlen := 0
+	if s.mac != nil && s.etm {
+		// packet length is not encrypted for EtM modes
+		aadlen = 4
+	}
+
+	paddingLength := packetSizeMultiple - (prefixLen+len(packet)-aadlen)%packetSizeMultiple
+	if paddingLength < 4 {
+		paddingLength += packetSizeMultiple
+	}
+
+	length := len(packet) + 1 + paddingLength
+	binary.BigEndian.PutUint32(s.prefix[:], uint32(length))
+	s.prefix[4] = byte(paddingLength)
+	padding := s.padding[:paddingLength]
+	if _, err := io.ReadFull(rand, padding); err != nil {
+		return err
+	}
+
+	if s.mac != nil {
+		s.mac.Reset()
+		binary.BigEndian.PutUint32(s.seqNumBytes[:], seqNum)
+		s.mac.Write(s.seqNumBytes[:])
+
+		if s.etm {
+			// For EtM algorithms, the packet length must stay unencrypted,
+			// but the following data (padding length) must be encrypted
+			s.cipher.XORKeyStream(s.prefix[4:5], s.prefix[4:5])
+		}
+
+		s.mac.Write(s.prefix[:])
+
+		if !s.etm {
+			// For non-EtM algorithms, the algorithm is applied on unencrypted data
+			s.mac.Write(packet)
+			s.mac.Write(padding)
+		}
+	}
+
+	if !(s.mac != nil && s.etm) {
+		// For EtM algorithms, the padding length has already been encrypted
+		// and the packet length must remain unencrypted
+		s.cipher.XORKeyStream(s.prefix[:], s.prefix[:])
+	}
+
+	s.cipher.XORKeyStream(packet, packet)
+	s.cipher.XORKeyStream(padding, padding)
+
+	if s.mac != nil && s.etm {
+		// For EtM algorithms, packet and padding must be encrypted
+		s.mac.Write(packet)
+		s.mac.Write(padding)
+	}
+
+	if _, err := w.Write(s.prefix[:]); err != nil {
+		return err
+	}
+	if _, err := w.Write(packet); err != nil {
+		return err
+	}
+	if _, err := w.Write(padding); err != nil {
+		return err
+	}
+
+	if s.mac != nil {
+		s.macResult = s.mac.Sum(s.macResult[:0])
+		if _, err := w.Write(s.macResult); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+type gcmCipher struct {
+	aead   cipher.AEAD
+	prefix [4]byte
+	iv     []byte
+	buf    []byte
+}
+
+func newGCMCipher(key, iv, unusedMacKey []byte, unusedAlgs directionAlgorithms) (packetCipher, error) {
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	aead, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+
+	return &gcmCipher{
+		aead: aead,
+		iv:   iv,
+	}, nil
+}
+
+const gcmTagSize = 16
+
+func (c *gcmCipher) writeCipherPacket(seqNum uint32, w io.Writer, rand io.Reader, packet []byte) error {
+	// Pad out to multiple of 16 bytes. This is different from the
+	// stream cipher because that encrypts the length too.
+	padding := byte(packetSizeMultiple - (1+len(packet))%packetSizeMultiple)
+	if padding < 4 {
+		padding += packetSizeMultiple
+	}
+
+	length := uint32(len(packet) + int(padding) + 1)
+	binary.BigEndian.PutUint32(c.prefix[:], length)
+	if _, err := w.Write(c.prefix[:]); err != nil {
+		return err
+	}
+
+	if cap(c.buf) < int(length) {
+		c.buf = make([]byte, length)
+	} else {
+		c.buf = c.buf[:length]
+	}
+
+	c.buf[0] = padding
+	copy(c.buf[1:], packet)
+	if _, err := io.ReadFull(rand, c.buf[1+len(packet):]); err != nil {
+		return err
+	}
+	c.buf = c.aead.Seal(c.buf[:0], c.iv, c.buf, c.prefix[:])
+	if _, err := w.Write(c.buf); err != nil {
+		return err
+	}
+	c.incIV()
+
+	return nil
+}
+
+func (c *gcmCipher) incIV() {
+	for i := 4 + 7; i >= 4; i-- {
+		c.iv[i]++
+		if c.iv[i] != 0 {
+			break
+		}
+	}
+}
+
+func (c *gcmCipher) readCipherPacket(seqNum uint32, r io.Reader) ([]byte, error) {
+	if _, err := io.ReadFull(r, c.prefix[:]); err != nil {
+		return nil, err
+	}
+	length := binary.BigEndian.Uint32(c.prefix[:])
+	if length > maxPacket {
+		return nil, errors.New("ssh: max packet length exceeded")
+	}
+
+	if cap(c.buf) < int(length+gcmTagSize) {
+		c.buf = make([]byte, length+gcmTagSize)
+	} else {
+		c.buf = c.buf[:length+gcmTagSize]
+	}
+
+	if _, err := io.ReadFull(r, c.buf); err != nil {
+		return nil, err
+	}
+
+	plain, err := c.aead.Open(c.buf[:0], c.iv, c.buf, c.prefix[:])
+	if err != nil {
+		return nil, err
+	}
+	c.incIV()
+
+	if len(plain) == 0 {
+		return nil, errors.New("ssh: empty packet")
+	}
+
+	padding := plain[0]
+	if padding < 4 {
+		// padding is a byte, so it automatically satisfies
+		// the maximum size, which is 255.
+		return nil, fmt.Errorf("ssh: illegal padding %d", padding)
+	}
+
+	if int(padding+1) >= len(plain) {
+		return nil, fmt.Errorf("ssh: padding %d too large", padding)
+	}
+	plain = plain[1 : length-uint32(padding)]
+	return plain, nil
+}
+
+// cbcCipher implements aes128-cbc cipher defined in RFC 4253 section 6.1
+type cbcCipher struct {
+	mac       hash.Hash
+	macSize   uint32
+	decrypter cipher.BlockMode
+	encrypter cipher.BlockMode
+
+	// The following members are to avoid per-packet allocations.
+	seqNumBytes [4]byte
+	packetData  []byte
+	macResult   []byte
+
+	// Amount of data we should still read to hide which
+	// verification error triggered.
+	oracleCamouflage uint32
+}
+
+func newCBCCipher(c cipher.Block, key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	cbc := &cbcCipher{
+		mac:        macModes[algs.MAC].new(macKey),
+		decrypter:  cipher.NewCBCDecrypter(c, iv),
+		encrypter:  cipher.NewCBCEncrypter(c, iv),
+		packetData: make([]byte, 1024),
+	}
+	if cbc.mac != nil {
+		cbc.macSize = uint32(cbc.mac.Size())
+	}
+
+	return cbc, nil
+}
+
+func newAESCBCCipher(key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	cbc, err := newCBCCipher(c, key, iv, macKey, algs)
+	if err != nil {
+		return nil, err
+	}
+
+	return cbc, nil
+}
+
+func newTripleDESCBCCipher(key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	c, err := des.NewTripleDESCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	cbc, err := newCBCCipher(c, key, iv, macKey, algs)
+	if err != nil {
+		return nil, err
+	}
+
+	return cbc, nil
+}
+
+func maxUInt32(a, b int) uint32 {
+	if a > b {
+		return uint32(a)
+	}
+	return uint32(b)
+}
+
+const (
+	cbcMinPacketSizeMultiple = 8
+	cbcMinPacketSize         = 16
+	cbcMinPaddingSize        = 4
+)
+
+// cbcError represents a verification error that may leak information.
+type cbcError string
+
+func (e cbcError) Error() string { return string(e) }
+
+func (c *cbcCipher) readCipherPacket(seqNum uint32, r io.Reader) ([]byte, error) {
+	p, err := c.readCipherPacketLeaky(seqNum, r)
+	if err != nil {
+		if _, ok := err.(cbcError); ok {
+			// Verification error: read a fixed amount of
+			// data, to make distinguishing between
+			// failing MAC and failing length check more
+			// difficult.
+			io.CopyN(io.Discard, r, int64(c.oracleCamouflage))
+		}
+	}
+	return p, err
+}
+
+func (c *cbcCipher) readCipherPacketLeaky(seqNum uint32, r io.Reader) ([]byte, error) {
+	blockSize := c.decrypter.BlockSize()
+
+	// Read the header, which will include some of the subsequent data in the
+	// case of block ciphers - this is copied back to the payload later.
+	// How many bytes of payload/padding will be read with this first read.
+	firstBlockLength := uint32((prefixLen + blockSize - 1) / blockSize * blockSize)
+	firstBlock := c.packetData[:firstBlockLength]
+	if _, err := io.ReadFull(r, firstBlock); err != nil {
+		return nil, err
+	}
+
+	c.oracleCamouflage = maxPacket + 4 + c.macSize - firstBlockLength
+
+	c.decrypter.CryptBlocks(firstBlock, firstBlock)
+	length := binary.BigEndian.Uint32(firstBlock[:4])
+	if length > maxPacket {
+		return nil, cbcError("ssh: packet too large")
+	}
+	if length+4 < maxUInt32(cbcMinPacketSize, blockSize) {
+		// The minimum size of a packet is 16 (or the cipher block size, whichever
+		// is larger) bytes.
+		return nil, cbcError("ssh: packet too small")
+	}
+	// The length of the packet (including the length field but not the MAC) must
+	// be a multiple of the block size or 8, whichever is larger.
+	if (length+4)%maxUInt32(cbcMinPacketSizeMultiple, blockSize) != 0 {
+		return nil, cbcError("ssh: invalid packet length multiple")
+	}
+
+	paddingLength := uint32(firstBlock[4])
+	if paddingLength < cbcMinPaddingSize || length <= paddingLength+1 {
+		return nil, cbcError("ssh: invalid packet length")
+	}
+
+	// Positions within the c.packetData buffer:
+	macStart := 4 + length
+	paddingStart := macStart - paddingLength
+
+	// Entire packet size, starting before length, ending at end of mac.
+	entirePacketSize := macStart + c.macSize
+
+	// Ensure c.packetData is large enough for the entire packet data.
+	if uint32(cap(c.packetData)) < entirePacketSize {
+		// Still need to upsize and copy, but this should be rare at runtime, only
+		// on upsizing the packetData buffer.
+		c.packetData = make([]byte, entirePacketSize)
+		copy(c.packetData, firstBlock)
+	} else {
+		c.packetData = c.packetData[:entirePacketSize]
+	}
+
+	n, err := io.ReadFull(r, c.packetData[firstBlockLength:])
+	if err != nil {
+		return nil, err
+	}
+	c.oracleCamouflage -= uint32(n)
+
+	remainingCrypted := c.packetData[firstBlockLength:macStart]
+	c.decrypter.CryptBlocks(remainingCrypted, remainingCrypted)
+
+	mac := c.packetData[macStart:]
+	if c.mac != nil {
+		c.mac.Reset()
+		binary.BigEndian.PutUint32(c.seqNumBytes[:], seqNum)
+		c.mac.Write(c.seqNumBytes[:])
+		c.mac.Write(c.packetData[:macStart])
+		c.macResult = c.mac.Sum(c.macResult[:0])
+		if subtle.ConstantTimeCompare(c.macResult, mac) != 1 {
+			return nil, cbcError("ssh: MAC failure")
+		}
+	}
+
+	return c.packetData[prefixLen:paddingStart], nil
+}
+
+func (c *cbcCipher) writeCipherPacket(seqNum uint32, w io.Writer, rand io.Reader, packet []byte) error {
+	effectiveBlockSize := maxUInt32(cbcMinPacketSizeMultiple, c.encrypter.BlockSize())
+
+	// Length of encrypted portion of the packet (header, payload, padding).
+	// Enforce minimum padding and packet size.
+	encLength := maxUInt32(prefixLen+len(packet)+cbcMinPaddingSize, cbcMinPaddingSize)
+	// Enforce block size.
+	encLength = (encLength + effectiveBlockSize - 1) / effectiveBlockSize * effectiveBlockSize
+
+	length := encLength - 4
+	paddingLength := int(length) - (1 + len(packet))
+
+	// Overall buffer contains: header, payload, padding, mac.
+	// Space for the MAC is reserved in the capacity but not the slice length.
+	bufferSize := encLength + c.macSize
+	if uint32(cap(c.packetData)) < bufferSize {
+		c.packetData = make([]byte, encLength, bufferSize)
+	} else {
+		c.packetData = c.packetData[:encLength]
+	}
+
+	p := c.packetData
+
+	// Packet header.
+	binary.BigEndian.PutUint32(p, length)
+	p = p[4:]
+	p[0] = byte(paddingLength)
+
+	// Payload.
+	p = p[1:]
+	copy(p, packet)
+
+	// Padding.
+	p = p[len(packet):]
+	if _, err := io.ReadFull(rand, p); err != nil {
+		return err
+	}
+
+	if c.mac != nil {
+		c.mac.Reset()
+		binary.BigEndian.PutUint32(c.seqNumBytes[:], seqNum)
+		c.mac.Write(c.seqNumBytes[:])
+		c.mac.Write(c.packetData)
+		// The MAC is now appended into the capacity reserved for it earlier.
+		c.packetData = c.mac.Sum(c.packetData)
+	}
+
+	c.encrypter.CryptBlocks(c.packetData[:encLength], c.packetData[:encLength])
+
+	if _, err := w.Write(c.packetData); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+const chacha20Poly1305ID = "chacha20-poly1305@openssh.com"
+
+// chacha20Poly1305Cipher implements the chacha20-poly1305@openssh.com
+// AEAD, which is described here:
+//
+//	https://tools.ietf.org/html/draft-josefsson-ssh-chacha20-poly1305-openssh-00
+//
+// the methods here also implement padding, which RFC 4253 Section 6
+// also requires of stream ciphers.
+type chacha20Poly1305Cipher struct {
+	lengthKey  [32]byte
+	contentKey [32]byte
+	buf        []byte
+}
+
+func newChaCha20Cipher(key, unusedIV, unusedMACKey []byte, unusedAlgs directionAlgorithms) (packetCipher, error) {
+	if len(key) != 64 {
+		panic(len(key))
+	}
+
+	c := &chacha20Poly1305Cipher{
+		buf: make([]byte, 256),
+	}
+
+	copy(c.contentKey[:], key[:32])
+	copy(c.lengthKey[:], key[32:])
+	return c, nil
+}
+
+func (c *chacha20Poly1305Cipher) readCipherPacket(seqNum uint32, r io.Reader) ([]byte, error) {
+	nonce := make([]byte, 12)
+	binary.BigEndian.PutUint32(nonce[8:], seqNum)
+	s, err := chacha20.NewUnauthenticatedCipher(c.contentKey[:], nonce)
+	if err != nil {
+		return nil, err
+	}
+	var polyKey, discardBuf [32]byte
+	s.XORKeyStream(polyKey[:], polyKey[:])
+	s.XORKeyStream(discardBuf[:], discardBuf[:]) // skip the next 32 bytes
+
+	encryptedLength := c.buf[:4]
+	if _, err := io.ReadFull(r, encryptedLength); err != nil {
+		return nil, err
+	}
+
+	var lenBytes [4]byte
+	ls, err := chacha20.NewUnauthenticatedCipher(c.lengthKey[:], nonce)
+	if err != nil {
+		return nil, err
+	}
+	ls.XORKeyStream(lenBytes[:], encryptedLength)
+
+	length := binary.BigEndian.Uint32(lenBytes[:])
+	if length > maxPacket {
+		return nil, errors.New("ssh: invalid packet length, packet too large")
+	}
+
+	contentEnd := 4 + length
+	packetEnd := contentEnd + poly1305.TagSize
+	if uint32(cap(c.buf)) < packetEnd {
+		c.buf = make([]byte, packetEnd)
+		copy(c.buf[:], encryptedLength)
+	} else {
+		c.buf = c.buf[:packetEnd]
+	}
+
+	if _, err := io.ReadFull(r, c.buf[4:packetEnd]); err != nil {
+		return nil, err
+	}
+
+	var mac [poly1305.TagSize]byte
+	copy(mac[:], c.buf[contentEnd:packetEnd])
+	if !poly1305.Verify(&mac, c.buf[:contentEnd], &polyKey) {
+		return nil, errors.New("ssh: MAC failure")
+	}
+
+	plain := c.buf[4:contentEnd]
+	s.XORKeyStream(plain, plain)
+
+	if len(plain) == 0 {
+		return nil, errors.New("ssh: empty packet")
+	}
+
+	padding := plain[0]
+	if padding < 4 {
+		// padding is a byte, so it automatically satisfies
+		// the maximum size, which is 255.
+		return nil, fmt.Errorf("ssh: illegal padding %d", padding)
+	}
+
+	if int(padding)+1 >= len(plain) {
+		return nil, fmt.Errorf("ssh: padding %d too large", padding)
+	}
+
+	plain = plain[1 : len(plain)-int(padding)]
+
+	return plain, nil
+}
+
+func (c *chacha20Poly1305Cipher) writeCipherPacket(seqNum uint32, w io.Writer, rand io.Reader, payload []byte) error {
+	nonce := make([]byte, 12)
+	binary.BigEndian.PutUint32(nonce[8:], seqNum)
+	s, err := chacha20.NewUnauthenticatedCipher(c.contentKey[:], nonce)
+	if err != nil {
+		return err
+	}
+	var polyKey, discardBuf [32]byte
+	s.XORKeyStream(polyKey[:], polyKey[:])
+	s.XORKeyStream(discardBuf[:], discardBuf[:]) // skip the next 32 bytes
+
+	// There is no blocksize, so fall back to multiple of 8 byte
+	// padding, as described in RFC 4253, Sec 6.
+	const packetSizeMultiple = 8
+
+	padding := packetSizeMultiple - (1+len(payload))%packetSizeMultiple
+	if padding < 4 {
+		padding += packetSizeMultiple
+	}
+
+	// size (4 bytes), padding (1), payload, padding, tag.
+	totalLength := 4 + 1 + len(payload) + padding + poly1305.TagSize
+	if cap(c.buf) < totalLength {
+		c.buf = make([]byte, totalLength)
+	} else {
+		c.buf = c.buf[:totalLength]
+	}
+
+	binary.BigEndian.PutUint32(c.buf, uint32(1+len(payload)+padding))
+	ls, err := chacha20.NewUnauthenticatedCipher(c.lengthKey[:], nonce)
+	if err != nil {
+		return err
+	}
+	ls.XORKeyStream(c.buf, c.buf[:4])
+	c.buf[4] = byte(padding)
+	copy(c.buf[5:], payload)
+	packetEnd := 5 + len(payload) + padding
+	if _, err := io.ReadFull(rand, c.buf[5+len(payload):packetEnd]); err != nil {
+		return err
+	}
+
+	s.XORKeyStream(c.buf[4:], c.buf[4:packetEnd])
+
+	var mac [poly1305.TagSize]byte
+	poly1305.Sum(&mac, c.buf[:packetEnd], &polyKey)
+
+	copy(c.buf[packetEnd:], mac[:])
+
+	if _, err := w.Write(c.buf); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/vendor/golang.org/x/crypto/ssh/client.go b/vendor/golang.org/x/crypto/ssh/client.go
new file mode 100644
index 000000000..fd8c49749
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/client.go
@@ -0,0 +1,282 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"sync"
+	"time"
+)
+
+// Client implements a traditional SSH client that supports shells,
+// subprocesses, TCP port/streamlocal forwarding and tunneled dialing.
+type Client struct {
+	Conn
+
+	handleForwardsOnce sync.Once // guards calling (*Client).handleForwards
+
+	forwards        forwardList // forwarded tcpip connections from the remote side
+	mu              sync.Mutex
+	channelHandlers map[string]chan NewChannel
+}
+
+// HandleChannelOpen returns a channel on which NewChannel requests
+// for the given type are sent. If the type already is being handled,
+// nil is returned. The channel is closed when the connection is closed.
+func (c *Client) HandleChannelOpen(channelType string) <-chan NewChannel {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.channelHandlers == nil {
+		// The SSH channel has been closed.
+		c := make(chan NewChannel)
+		close(c)
+		return c
+	}
+
+	ch := c.channelHandlers[channelType]
+	if ch != nil {
+		return nil
+	}
+
+	ch = make(chan NewChannel, chanSize)
+	c.channelHandlers[channelType] = ch
+	return ch
+}
+
+// NewClient creates a Client on top of the given connection.
+func NewClient(c Conn, chans <-chan NewChannel, reqs <-chan *Request) *Client {
+	conn := &Client{
+		Conn:            c,
+		channelHandlers: make(map[string]chan NewChannel, 1),
+	}
+
+	go conn.handleGlobalRequests(reqs)
+	go conn.handleChannelOpens(chans)
+	go func() {
+		conn.Wait()
+		conn.forwards.closeAll()
+	}()
+	return conn
+}
+
+// NewClientConn establishes an authenticated SSH connection using c
+// as the underlying transport.  The Request and NewChannel channels
+// must be serviced or the connection will hang.
+func NewClientConn(c net.Conn, addr string, config *ClientConfig) (Conn, <-chan NewChannel, <-chan *Request, error) {
+	fullConf := *config
+	fullConf.SetDefaults()
+	if fullConf.HostKeyCallback == nil {
+		c.Close()
+		return nil, nil, nil, errors.New("ssh: must specify HostKeyCallback")
+	}
+
+	conn := &connection{
+		sshConn: sshConn{conn: c, user: fullConf.User},
+	}
+
+	if err := conn.clientHandshake(addr, &fullConf); err != nil {
+		c.Close()
+		return nil, nil, nil, fmt.Errorf("ssh: handshake failed: %w", err)
+	}
+	conn.mux = newMux(conn.transport)
+	return conn, conn.mux.incomingChannels, conn.mux.incomingRequests, nil
+}
+
+// clientHandshake performs the client side key exchange. See RFC 4253 Section
+// 7.
+func (c *connection) clientHandshake(dialAddress string, config *ClientConfig) error {
+	if config.ClientVersion != "" {
+		c.clientVersion = []byte(config.ClientVersion)
+	} else {
+		c.clientVersion = []byte(packageVersion)
+	}
+	var err error
+	c.serverVersion, err = exchangeVersions(c.sshConn.conn, c.clientVersion)
+	if err != nil {
+		return err
+	}
+
+	c.transport = newClientTransport(
+		newTransport(c.sshConn.conn, config.Rand, true /* is client */),
+		c.clientVersion, c.serverVersion, config, dialAddress, c.sshConn.RemoteAddr())
+	if err := c.transport.waitSession(); err != nil {
+		return err
+	}
+
+	c.sessionID = c.transport.getSessionID()
+	return c.clientAuthenticate(config)
+}
+
+// verifyHostKeySignature verifies the host key obtained in the key exchange.
+// algo is the negotiated algorithm, and may be a certificate type.
+func verifyHostKeySignature(hostKey PublicKey, algo string, result *kexResult) error {
+	sig, rest, ok := parseSignatureBody(result.Signature)
+	if len(rest) > 0 || !ok {
+		return errors.New("ssh: signature parse error")
+	}
+
+	if a := underlyingAlgo(algo); sig.Format != a {
+		return fmt.Errorf("ssh: invalid signature algorithm %q, expected %q", sig.Format, a)
+	}
+
+	return hostKey.Verify(result.H, sig)
+}
+
+// NewSession opens a new Session for this client. (A session is a remote
+// execution of a program.)
+func (c *Client) NewSession() (*Session, error) {
+	ch, in, err := c.OpenChannel("session", nil)
+	if err != nil {
+		return nil, err
+	}
+	return newSession(ch, in)
+}
+
+func (c *Client) handleGlobalRequests(incoming <-chan *Request) {
+	for r := range incoming {
+		// This handles keepalive messages and matches
+		// the behaviour of OpenSSH.
+		r.Reply(false, nil)
+	}
+}
+
+// handleChannelOpens channel open messages from the remote side.
+func (c *Client) handleChannelOpens(in <-chan NewChannel) {
+	for ch := range in {
+		c.mu.Lock()
+		handler := c.channelHandlers[ch.ChannelType()]
+		c.mu.Unlock()
+
+		if handler != nil {
+			handler <- ch
+		} else {
+			ch.Reject(UnknownChannelType, fmt.Sprintf("unknown channel type: %v", ch.ChannelType()))
+		}
+	}
+
+	c.mu.Lock()
+	for _, ch := range c.channelHandlers {
+		close(ch)
+	}
+	c.channelHandlers = nil
+	c.mu.Unlock()
+}
+
+// Dial starts a client connection to the given SSH server. It is a
+// convenience function that connects to the given network address,
+// initiates the SSH handshake, and then sets up a Client.  For access
+// to incoming channels and requests, use net.Dial with NewClientConn
+// instead.
+func Dial(network, addr string, config *ClientConfig) (*Client, error) {
+	conn, err := net.DialTimeout(network, addr, config.Timeout)
+	if err != nil {
+		return nil, err
+	}
+	c, chans, reqs, err := NewClientConn(conn, addr, config)
+	if err != nil {
+		return nil, err
+	}
+	return NewClient(c, chans, reqs), nil
+}
+
+// HostKeyCallback is the function type used for verifying server
+// keys.  A HostKeyCallback must return nil if the host key is OK, or
+// an error to reject it. It receives the hostname as passed to Dial
+// or NewClientConn. The remote address is the RemoteAddr of the
+// net.Conn underlying the SSH connection.
+type HostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
+
+// BannerCallback is the function type used for treat the banner sent by
+// the server. A BannerCallback receives the message sent by the remote server.
+type BannerCallback func(message string) error
+
+// A ClientConfig structure is used to configure a Client. It must not be
+// modified after having been passed to an SSH function.
+type ClientConfig struct {
+	// Config contains configuration that is shared between clients and
+	// servers.
+	Config
+
+	// User contains the username to authenticate as.
+	User string
+
+	// Auth contains possible authentication methods to use with the
+	// server. Only the first instance of a particular RFC 4252 method will
+	// be used during authentication.
+	Auth []AuthMethod
+
+	// HostKeyCallback is called during the cryptographic
+	// handshake to validate the server's host key. The client
+	// configuration must supply this callback for the connection
+	// to succeed. The functions InsecureIgnoreHostKey or
+	// FixedHostKey can be used for simplistic host key checks.
+	HostKeyCallback HostKeyCallback
+
+	// BannerCallback is called during the SSH dance to display a custom
+	// server's message. The client configuration can supply this callback to
+	// handle it as wished. The function BannerDisplayStderr can be used for
+	// simplistic display on Stderr.
+	BannerCallback BannerCallback
+
+	// ClientVersion contains the version identification string that will
+	// be used for the connection. If empty, a reasonable default is used.
+	ClientVersion string
+
+	// HostKeyAlgorithms lists the public key algorithms that the client will
+	// accept from the server for host key authentication, in order of
+	// preference. If empty, a reasonable default is used. Any
+	// string returned from a PublicKey.Type method may be used, or
+	// any of the CertAlgo and KeyAlgo constants.
+	HostKeyAlgorithms []string
+
+	// Timeout is the maximum amount of time for the TCP connection to establish.
+	//
+	// A Timeout of zero means no timeout.
+	Timeout time.Duration
+}
+
+// InsecureIgnoreHostKey returns a function that can be used for
+// ClientConfig.HostKeyCallback to accept any host key. It should
+// not be used for production code.
+func InsecureIgnoreHostKey() HostKeyCallback {
+	return func(hostname string, remote net.Addr, key PublicKey) error {
+		return nil
+	}
+}
+
+type fixedHostKey struct {
+	key PublicKey
+}
+
+func (f *fixedHostKey) check(hostname string, remote net.Addr, key PublicKey) error {
+	if f.key == nil {
+		return fmt.Errorf("ssh: required host key was nil")
+	}
+	if !bytes.Equal(key.Marshal(), f.key.Marshal()) {
+		return fmt.Errorf("ssh: host key mismatch")
+	}
+	return nil
+}
+
+// FixedHostKey returns a function for use in
+// ClientConfig.HostKeyCallback to accept only a specific host key.
+func FixedHostKey(key PublicKey) HostKeyCallback {
+	hk := &fixedHostKey{key}
+	return hk.check
+}
+
+// BannerDisplayStderr returns a function that can be used for
+// ClientConfig.BannerCallback to display banners on os.Stderr.
+func BannerDisplayStderr() BannerCallback {
+	return func(banner string) error {
+		_, err := os.Stderr.WriteString(banner)
+
+		return err
+	}
+}
diff --git a/vendor/golang.org/x/crypto/ssh/client_auth.go b/vendor/golang.org/x/crypto/ssh/client_auth.go
new file mode 100644
index 000000000..9486c5986
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/client_auth.go
@@ -0,0 +1,787 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+)
+
+type authResult int
+
+const (
+	authFailure authResult = iota
+	authPartialSuccess
+	authSuccess
+)
+
+// clientAuthenticate authenticates with the remote server. See RFC 4252.
+func (c *connection) clientAuthenticate(config *ClientConfig) error {
+	// initiate user auth session
+	if err := c.transport.writePacket(Marshal(&serviceRequestMsg{serviceUserAuth})); err != nil {
+		return err
+	}
+	packet, err := c.transport.readPacket()
+	if err != nil {
+		return err
+	}
+	// The server may choose to send a SSH_MSG_EXT_INFO at this point (if we
+	// advertised willingness to receive one, which we always do) or not. See
+	// RFC 8308, Section 2.4.
+	extensions := make(map[string][]byte)
+	if len(packet) > 0 && packet[0] == msgExtInfo {
+		var extInfo extInfoMsg
+		if err := Unmarshal(packet, &extInfo); err != nil {
+			return err
+		}
+		payload := extInfo.Payload
+		for i := uint32(0); i < extInfo.NumExtensions; i++ {
+			name, rest, ok := parseString(payload)
+			if !ok {
+				return parseError(msgExtInfo)
+			}
+			value, rest, ok := parseString(rest)
+			if !ok {
+				return parseError(msgExtInfo)
+			}
+			extensions[string(name)] = value
+			payload = rest
+		}
+		packet, err = c.transport.readPacket()
+		if err != nil {
+			return err
+		}
+	}
+	var serviceAccept serviceAcceptMsg
+	if err := Unmarshal(packet, &serviceAccept); err != nil {
+		return err
+	}
+
+	// during the authentication phase the client first attempts the "none" method
+	// then any untried methods suggested by the server.
+	var tried []string
+	var lastMethods []string
+
+	sessionID := c.transport.getSessionID()
+	for auth := AuthMethod(new(noneAuth)); auth != nil; {
+		ok, methods, err := auth.auth(sessionID, config.User, c.transport, config.Rand, extensions)
+		if err != nil {
+			// We return the error later if there is no other method left to
+			// try.
+			ok = authFailure
+		}
+		if ok == authSuccess {
+			// success
+			return nil
+		} else if ok == authFailure {
+			if m := auth.method(); !contains(tried, m) {
+				tried = append(tried, m)
+			}
+		}
+		if methods == nil {
+			methods = lastMethods
+		}
+		lastMethods = methods
+
+		auth = nil
+
+	findNext:
+		for _, a := range config.Auth {
+			candidateMethod := a.method()
+			if contains(tried, candidateMethod) {
+				continue
+			}
+			for _, meth := range methods {
+				if meth == candidateMethod {
+					auth = a
+					break findNext
+				}
+			}
+		}
+
+		if auth == nil && err != nil {
+			// We have an error and there are no other authentication methods to
+			// try, so we return it.
+			return err
+		}
+	}
+	return fmt.Errorf("ssh: unable to authenticate, attempted methods %v, no supported methods remain", tried)
+}
+
+func contains(list []string, e string) bool {
+	for _, s := range list {
+		if s == e {
+			return true
+		}
+	}
+	return false
+}
+
+// An AuthMethod represents an instance of an RFC 4252 authentication method.
+type AuthMethod interface {
+	// auth authenticates user over transport t.
+	// Returns true if authentication is successful.
+	// If authentication is not successful, a []string of alternative
+	// method names is returned. If the slice is nil, it will be ignored
+	// and the previous set of possible methods will be reused.
+	auth(session []byte, user string, p packetConn, rand io.Reader, extensions map[string][]byte) (authResult, []string, error)
+
+	// method returns the RFC 4252 method name.
+	method() string
+}
+
+// "none" authentication, RFC 4252 section 5.2.
+type noneAuth int
+
+func (n *noneAuth) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) {
+	if err := c.writePacket(Marshal(&userAuthRequestMsg{
+		User:    user,
+		Service: serviceSSH,
+		Method:  "none",
+	})); err != nil {
+		return authFailure, nil, err
+	}
+
+	return handleAuthResponse(c)
+}
+
+func (n *noneAuth) method() string {
+	return "none"
+}
+
+// passwordCallback is an AuthMethod that fetches the password through
+// a function call, e.g. by prompting the user.
+type passwordCallback func() (password string, err error)
+
+func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) {
+	type passwordAuthMsg struct {
+		User     string `sshtype:"50"`
+		Service  string
+		Method   string
+		Reply    bool
+		Password string
+	}
+
+	pw, err := cb()
+	// REVIEW NOTE: is there a need to support skipping a password attempt?
+	// The program may only find out that the user doesn't have a password
+	// when prompting.
+	if err != nil {
+		return authFailure, nil, err
+	}
+
+	if err := c.writePacket(Marshal(&passwordAuthMsg{
+		User:     user,
+		Service:  serviceSSH,
+		Method:   cb.method(),
+		Reply:    false,
+		Password: pw,
+	})); err != nil {
+		return authFailure, nil, err
+	}
+
+	return handleAuthResponse(c)
+}
+
+func (cb passwordCallback) method() string {
+	return "password"
+}
+
+// Password returns an AuthMethod using the given password.
+func Password(secret string) AuthMethod {
+	return passwordCallback(func() (string, error) { return secret, nil })
+}
+
+// PasswordCallback returns an AuthMethod that uses a callback for
+// fetching a password.
+func PasswordCallback(prompt func() (secret string, err error)) AuthMethod {
+	return passwordCallback(prompt)
+}
+
+type publickeyAuthMsg struct {
+	User    string `sshtype:"50"`
+	Service string
+	Method  string
+	// HasSig indicates to the receiver packet that the auth request is signed and
+	// should be used for authentication of the request.
+	HasSig   bool
+	Algoname string
+	PubKey   []byte
+	// Sig is tagged with "rest" so Marshal will exclude it during
+	// validateKey
+	Sig []byte `ssh:"rest"`
+}
+
+// publicKeyCallback is an AuthMethod that uses a set of key
+// pairs for authentication.
+type publicKeyCallback func() ([]Signer, error)
+
+func (cb publicKeyCallback) method() string {
+	return "publickey"
+}
+
+func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (MultiAlgorithmSigner, string, error) {
+	var as MultiAlgorithmSigner
+	keyFormat := signer.PublicKey().Type()
+
+	// If the signer implements MultiAlgorithmSigner we use the algorithms it
+	// support, if it implements AlgorithmSigner we assume it supports all
+	// algorithms, otherwise only the key format one.
+	switch s := signer.(type) {
+	case MultiAlgorithmSigner:
+		as = s
+	case AlgorithmSigner:
+		as = &multiAlgorithmSigner{
+			AlgorithmSigner:     s,
+			supportedAlgorithms: algorithmsForKeyFormat(underlyingAlgo(keyFormat)),
+		}
+	default:
+		as = &multiAlgorithmSigner{
+			AlgorithmSigner:     algorithmSignerWrapper{signer},
+			supportedAlgorithms: []string{underlyingAlgo(keyFormat)},
+		}
+	}
+
+	getFallbackAlgo := func() (string, error) {
+		// Fallback to use if there is no "server-sig-algs" extension or a
+		// common algorithm cannot be found. We use the public key format if the
+		// MultiAlgorithmSigner supports it, otherwise we return an error.
+		if !contains(as.Algorithms(), underlyingAlgo(keyFormat)) {
+			return "", fmt.Errorf("ssh: no common public key signature algorithm, server only supports %q for key type %q, signer only supports %v",
+				underlyingAlgo(keyFormat), keyFormat, as.Algorithms())
+		}
+		return keyFormat, nil
+	}
+
+	extPayload, ok := extensions["server-sig-algs"]
+	if !ok {
+		// If there is no "server-sig-algs" extension use the fallback
+		// algorithm.
+		algo, err := getFallbackAlgo()
+		return as, algo, err
+	}
+
+	// The server-sig-algs extension only carries underlying signature
+	// algorithm, but we are trying to select a protocol-level public key
+	// algorithm, which might be a certificate type. Extend the list of server
+	// supported algorithms to include the corresponding certificate algorithms.
+	serverAlgos := strings.Split(string(extPayload), ",")
+	for _, algo := range serverAlgos {
+		if certAlgo, ok := certificateAlgo(algo); ok {
+			serverAlgos = append(serverAlgos, certAlgo)
+		}
+	}
+
+	// Filter algorithms based on those supported by MultiAlgorithmSigner.
+	var keyAlgos []string
+	for _, algo := range algorithmsForKeyFormat(keyFormat) {
+		if contains(as.Algorithms(), underlyingAlgo(algo)) {
+			keyAlgos = append(keyAlgos, algo)
+		}
+	}
+
+	algo, err := findCommon("public key signature algorithm", keyAlgos, serverAlgos)
+	if err != nil {
+		// If there is no overlap, return the fallback algorithm to support
+		// servers that fail to list all supported algorithms.
+		algo, err := getFallbackAlgo()
+		return as, algo, err
+	}
+	return as, algo, nil
+}
+
+func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader, extensions map[string][]byte) (authResult, []string, error) {
+	// Authentication is performed by sending an enquiry to test if a key is
+	// acceptable to the remote. If the key is acceptable, the client will
+	// attempt to authenticate with the valid key.  If not the client will repeat
+	// the process with the remaining keys.
+
+	signers, err := cb()
+	if err != nil {
+		return authFailure, nil, err
+	}
+	var methods []string
+	var errSigAlgo error
+
+	origSignersLen := len(signers)
+	for idx := 0; idx < len(signers); idx++ {
+		signer := signers[idx]
+		pub := signer.PublicKey()
+		as, algo, err := pickSignatureAlgorithm(signer, extensions)
+		if err != nil && errSigAlgo == nil {
+			// If we cannot negotiate a signature algorithm store the first
+			// error so we can return it to provide a more meaningful message if
+			// no other signers work.
+			errSigAlgo = err
+			continue
+		}
+		ok, err := validateKey(pub, algo, user, c)
+		if err != nil {
+			return authFailure, nil, err
+		}
+		// OpenSSH 7.2-7.7 advertises support for rsa-sha2-256 and rsa-sha2-512
+		// in the "server-sig-algs" extension but doesn't support these
+		// algorithms for certificate authentication, so if the server rejects
+		// the key try to use the obtained algorithm as if "server-sig-algs" had
+		// not been implemented if supported from the algorithm signer.
+		if !ok && idx < origSignersLen && isRSACert(algo) && algo != CertAlgoRSAv01 {
+			if contains(as.Algorithms(), KeyAlgoRSA) {
+				// We retry using the compat algorithm after all signers have
+				// been tried normally.
+				signers = append(signers, &multiAlgorithmSigner{
+					AlgorithmSigner:     as,
+					supportedAlgorithms: []string{KeyAlgoRSA},
+				})
+			}
+		}
+		if !ok {
+			continue
+		}
+
+		pubKey := pub.Marshal()
+		data := buildDataSignedForAuth(session, userAuthRequestMsg{
+			User:    user,
+			Service: serviceSSH,
+			Method:  cb.method(),
+		}, algo, pubKey)
+		sign, err := as.SignWithAlgorithm(rand, data, underlyingAlgo(algo))
+		if err != nil {
+			return authFailure, nil, err
+		}
+
+		// manually wrap the serialized signature in a string
+		s := Marshal(sign)
+		sig := make([]byte, stringLength(len(s)))
+		marshalString(sig, s)
+		msg := publickeyAuthMsg{
+			User:     user,
+			Service:  serviceSSH,
+			Method:   cb.method(),
+			HasSig:   true,
+			Algoname: algo,
+			PubKey:   pubKey,
+			Sig:      sig,
+		}
+		p := Marshal(&msg)
+		if err := c.writePacket(p); err != nil {
+			return authFailure, nil, err
+		}
+		var success authResult
+		success, methods, err = handleAuthResponse(c)
+		if err != nil {
+			return authFailure, nil, err
+		}
+
+		// If authentication succeeds or the list of available methods does not
+		// contain the "publickey" method, do not attempt to authenticate with any
+		// other keys.  According to RFC 4252 Section 7, the latter can occur when
+		// additional authentication methods are required.
+		if success == authSuccess || !contains(methods, cb.method()) {
+			return success, methods, err
+		}
+	}
+
+	return authFailure, methods, errSigAlgo
+}
+
+// validateKey validates the key provided is acceptable to the server.
+func validateKey(key PublicKey, algo string, user string, c packetConn) (bool, error) {
+	pubKey := key.Marshal()
+	msg := publickeyAuthMsg{
+		User:     user,
+		Service:  serviceSSH,
+		Method:   "publickey",
+		HasSig:   false,
+		Algoname: algo,
+		PubKey:   pubKey,
+	}
+	if err := c.writePacket(Marshal(&msg)); err != nil {
+		return false, err
+	}
+
+	return confirmKeyAck(key, c)
+}
+
+func confirmKeyAck(key PublicKey, c packetConn) (bool, error) {
+	pubKey := key.Marshal()
+
+	for {
+		packet, err := c.readPacket()
+		if err != nil {
+			return false, err
+		}
+		switch packet[0] {
+		case msgUserAuthBanner:
+			if err := handleBannerResponse(c, packet); err != nil {
+				return false, err
+			}
+		case msgUserAuthPubKeyOk:
+			var msg userAuthPubKeyOkMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return false, err
+			}
+			// According to RFC 4252 Section 7 the algorithm in
+			// SSH_MSG_USERAUTH_PK_OK should match that of the request but some
+			// servers send the key type instead. OpenSSH allows any algorithm
+			// that matches the public key, so we do the same.
+			// https://github.com/openssh/openssh-portable/blob/86bdd385/sshconnect2.c#L709
+			if !contains(algorithmsForKeyFormat(key.Type()), msg.Algo) {
+				return false, nil
+			}
+			if !bytes.Equal(msg.PubKey, pubKey) {
+				return false, nil
+			}
+			return true, nil
+		case msgUserAuthFailure:
+			return false, nil
+		default:
+			return false, unexpectedMessageError(msgUserAuthPubKeyOk, packet[0])
+		}
+	}
+}
+
+// PublicKeys returns an AuthMethod that uses the given key
+// pairs.
+func PublicKeys(signers ...Signer) AuthMethod {
+	return publicKeyCallback(func() ([]Signer, error) { return signers, nil })
+}
+
+// PublicKeysCallback returns an AuthMethod that runs the given
+// function to obtain a list of key pairs.
+func PublicKeysCallback(getSigners func() (signers []Signer, err error)) AuthMethod {
+	return publicKeyCallback(getSigners)
+}
+
+// handleAuthResponse returns whether the preceding authentication request succeeded
+// along with a list of remaining authentication methods to try next and
+// an error if an unexpected response was received.
+func handleAuthResponse(c packetConn) (authResult, []string, error) {
+	gotMsgExtInfo := false
+	for {
+		packet, err := c.readPacket()
+		if err != nil {
+			return authFailure, nil, err
+		}
+
+		switch packet[0] {
+		case msgUserAuthBanner:
+			if err := handleBannerResponse(c, packet); err != nil {
+				return authFailure, nil, err
+			}
+		case msgExtInfo:
+			// Ignore post-authentication RFC 8308 extensions, once.
+			if gotMsgExtInfo {
+				return authFailure, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0])
+			}
+			gotMsgExtInfo = true
+		case msgUserAuthFailure:
+			var msg userAuthFailureMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return authFailure, nil, err
+			}
+			if msg.PartialSuccess {
+				return authPartialSuccess, msg.Methods, nil
+			}
+			return authFailure, msg.Methods, nil
+		case msgUserAuthSuccess:
+			return authSuccess, nil, nil
+		default:
+			return authFailure, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0])
+		}
+	}
+}
+
+func handleBannerResponse(c packetConn, packet []byte) error {
+	var msg userAuthBannerMsg
+	if err := Unmarshal(packet, &msg); err != nil {
+		return err
+	}
+
+	transport, ok := c.(*handshakeTransport)
+	if !ok {
+		return nil
+	}
+
+	if transport.bannerCallback != nil {
+		return transport.bannerCallback(msg.Message)
+	}
+
+	return nil
+}
+
+// KeyboardInteractiveChallenge should print questions, optionally
+// disabling echoing (e.g. for passwords), and return all the answers.
+// Challenge may be called multiple times in a single session. After
+// successful authentication, the server may send a challenge with no
+// questions, for which the name and instruction messages should be
+// printed.  RFC 4256 section 3.3 details how the UI should behave for
+// both CLI and GUI environments.
+type KeyboardInteractiveChallenge func(name, instruction string, questions []string, echos []bool) (answers []string, err error)
+
+// KeyboardInteractive returns an AuthMethod using a prompt/response
+// sequence controlled by the server.
+func KeyboardInteractive(challenge KeyboardInteractiveChallenge) AuthMethod {
+	return challenge
+}
+
+func (cb KeyboardInteractiveChallenge) method() string {
+	return "keyboard-interactive"
+}
+
+func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) {
+	type initiateMsg struct {
+		User       string `sshtype:"50"`
+		Service    string
+		Method     string
+		Language   string
+		Submethods string
+	}
+
+	if err := c.writePacket(Marshal(&initiateMsg{
+		User:    user,
+		Service: serviceSSH,
+		Method:  "keyboard-interactive",
+	})); err != nil {
+		return authFailure, nil, err
+	}
+
+	gotMsgExtInfo := false
+	for {
+		packet, err := c.readPacket()
+		if err != nil {
+			return authFailure, nil, err
+		}
+
+		// like handleAuthResponse, but with less options.
+		switch packet[0] {
+		case msgUserAuthBanner:
+			if err := handleBannerResponse(c, packet); err != nil {
+				return authFailure, nil, err
+			}
+			continue
+		case msgExtInfo:
+			// Ignore post-authentication RFC 8308 extensions, once.
+			if gotMsgExtInfo {
+				return authFailure, nil, unexpectedMessageError(msgUserAuthInfoRequest, packet[0])
+			}
+			gotMsgExtInfo = true
+			continue
+		case msgUserAuthInfoRequest:
+			// OK
+		case msgUserAuthFailure:
+			var msg userAuthFailureMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return authFailure, nil, err
+			}
+			if msg.PartialSuccess {
+				return authPartialSuccess, msg.Methods, nil
+			}
+			return authFailure, msg.Methods, nil
+		case msgUserAuthSuccess:
+			return authSuccess, nil, nil
+		default:
+			return authFailure, nil, unexpectedMessageError(msgUserAuthInfoRequest, packet[0])
+		}
+
+		var msg userAuthInfoRequestMsg
+		if err := Unmarshal(packet, &msg); err != nil {
+			return authFailure, nil, err
+		}
+
+		// Manually unpack the prompt/echo pairs.
+		rest := msg.Prompts
+		var prompts []string
+		var echos []bool
+		for i := 0; i < int(msg.NumPrompts); i++ {
+			prompt, r, ok := parseString(rest)
+			if !ok || len(r) == 0 {
+				return authFailure, nil, errors.New("ssh: prompt format error")
+			}
+			prompts = append(prompts, string(prompt))
+			echos = append(echos, r[0] != 0)
+			rest = r[1:]
+		}
+
+		if len(rest) != 0 {
+			return authFailure, nil, errors.New("ssh: extra data following keyboard-interactive pairs")
+		}
+
+		answers, err := cb(msg.Name, msg.Instruction, prompts, echos)
+		if err != nil {
+			return authFailure, nil, err
+		}
+
+		if len(answers) != len(prompts) {
+			return authFailure, nil, fmt.Errorf("ssh: incorrect number of answers from keyboard-interactive callback %d (expected %d)", len(answers), len(prompts))
+		}
+		responseLength := 1 + 4
+		for _, a := range answers {
+			responseLength += stringLength(len(a))
+		}
+		serialized := make([]byte, responseLength)
+		p := serialized
+		p[0] = msgUserAuthInfoResponse
+		p = p[1:]
+		p = marshalUint32(p, uint32(len(answers)))
+		for _, a := range answers {
+			p = marshalString(p, []byte(a))
+		}
+
+		if err := c.writePacket(serialized); err != nil {
+			return authFailure, nil, err
+		}
+	}
+}
+
+type retryableAuthMethod struct {
+	authMethod AuthMethod
+	maxTries   int
+}
+
+func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader, extensions map[string][]byte) (ok authResult, methods []string, err error) {
+	for i := 0; r.maxTries <= 0 || i < r.maxTries; i++ {
+		ok, methods, err = r.authMethod.auth(session, user, c, rand, extensions)
+		if ok != authFailure || err != nil { // either success, partial success or error terminate
+			return ok, methods, err
+		}
+	}
+	return ok, methods, err
+}
+
+func (r *retryableAuthMethod) method() string {
+	return r.authMethod.method()
+}
+
+// RetryableAuthMethod is a decorator for other auth methods enabling them to
+// be retried up to maxTries before considering that AuthMethod itself failed.
+// If maxTries is <= 0, will retry indefinitely
+//
+// This is useful for interactive clients using challenge/response type
+// authentication (e.g. Keyboard-Interactive, Password, etc) where the user
+// could mistype their response resulting in the server issuing a
+// SSH_MSG_USERAUTH_FAILURE (rfc4252 #8 [password] and rfc4256 #3.4
+// [keyboard-interactive]); Without this decorator, the non-retryable
+// AuthMethod would be removed from future consideration, and never tried again
+// (and so the user would never be able to retry their entry).
+func RetryableAuthMethod(auth AuthMethod, maxTries int) AuthMethod {
+	return &retryableAuthMethod{authMethod: auth, maxTries: maxTries}
+}
+
+// GSSAPIWithMICAuthMethod is an AuthMethod with "gssapi-with-mic" authentication.
+// See RFC 4462 section 3
+// gssAPIClient is implementation of the GSSAPIClient interface, see the definition of the interface for details.
+// target is the server host you want to log in to.
+func GSSAPIWithMICAuthMethod(gssAPIClient GSSAPIClient, target string) AuthMethod {
+	if gssAPIClient == nil {
+		panic("gss-api client must be not nil with enable gssapi-with-mic")
+	}
+	return &gssAPIWithMICCallback{gssAPIClient: gssAPIClient, target: target}
+}
+
+type gssAPIWithMICCallback struct {
+	gssAPIClient GSSAPIClient
+	target       string
+}
+
+func (g *gssAPIWithMICCallback) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) {
+	m := &userAuthRequestMsg{
+		User:    user,
+		Service: serviceSSH,
+		Method:  g.method(),
+	}
+	// The GSS-API authentication method is initiated when the client sends an SSH_MSG_USERAUTH_REQUEST.
+	// See RFC 4462 section 3.2.
+	m.Payload = appendU32(m.Payload, 1)
+	m.Payload = appendString(m.Payload, string(krb5OID))
+	if err := c.writePacket(Marshal(m)); err != nil {
+		return authFailure, nil, err
+	}
+	// The server responds to the SSH_MSG_USERAUTH_REQUEST with either an
+	// SSH_MSG_USERAUTH_FAILURE if none of the mechanisms are supported or
+	// with an SSH_MSG_USERAUTH_GSSAPI_RESPONSE.
+	// See RFC 4462 section 3.3.
+	// OpenSSH supports Kerberos V5 mechanism only for GSS-API authentication,so I don't want to check
+	// selected mech if it is valid.
+	packet, err := c.readPacket()
+	if err != nil {
+		return authFailure, nil, err
+	}
+	userAuthGSSAPIResp := &userAuthGSSAPIResponse{}
+	if err := Unmarshal(packet, userAuthGSSAPIResp); err != nil {
+		return authFailure, nil, err
+	}
+	// Start the loop into the exchange token.
+	// See RFC 4462 section 3.4.
+	var token []byte
+	defer g.gssAPIClient.DeleteSecContext()
+	for {
+		// Initiates the establishment of a security context between the application and a remote peer.
+		nextToken, needContinue, err := g.gssAPIClient.InitSecContext("host@"+g.target, token, false)
+		if err != nil {
+			return authFailure, nil, err
+		}
+		if len(nextToken) > 0 {
+			if err := c.writePacket(Marshal(&userAuthGSSAPIToken{
+				Token: nextToken,
+			})); err != nil {
+				return authFailure, nil, err
+			}
+		}
+		if !needContinue {
+			break
+		}
+		packet, err = c.readPacket()
+		if err != nil {
+			return authFailure, nil, err
+		}
+		switch packet[0] {
+		case msgUserAuthFailure:
+			var msg userAuthFailureMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return authFailure, nil, err
+			}
+			if msg.PartialSuccess {
+				return authPartialSuccess, msg.Methods, nil
+			}
+			return authFailure, msg.Methods, nil
+		case msgUserAuthGSSAPIError:
+			userAuthGSSAPIErrorResp := &userAuthGSSAPIError{}
+			if err := Unmarshal(packet, userAuthGSSAPIErrorResp); err != nil {
+				return authFailure, nil, err
+			}
+			return authFailure, nil, fmt.Errorf("GSS-API Error:\n"+
+				"Major Status: %d\n"+
+				"Minor Status: %d\n"+
+				"Error Message: %s\n", userAuthGSSAPIErrorResp.MajorStatus, userAuthGSSAPIErrorResp.MinorStatus,
+				userAuthGSSAPIErrorResp.Message)
+		case msgUserAuthGSSAPIToken:
+			userAuthGSSAPITokenReq := &userAuthGSSAPIToken{}
+			if err := Unmarshal(packet, userAuthGSSAPITokenReq); err != nil {
+				return authFailure, nil, err
+			}
+			token = userAuthGSSAPITokenReq.Token
+		}
+	}
+	// Binding Encryption Keys.
+	// See RFC 4462 section 3.5.
+	micField := buildMIC(string(session), user, "ssh-connection", "gssapi-with-mic")
+	micToken, err := g.gssAPIClient.GetMIC(micField)
+	if err != nil {
+		return authFailure, nil, err
+	}
+	if err := c.writePacket(Marshal(&userAuthGSSAPIMIC{
+		MIC: micToken,
+	})); err != nil {
+		return authFailure, nil, err
+	}
+	return handleAuthResponse(c)
+}
+
+func (g *gssAPIWithMICCallback) method() string {
+	return "gssapi-with-mic"
+}
diff --git a/vendor/golang.org/x/crypto/ssh/common.go b/vendor/golang.org/x/crypto/ssh/common.go
new file mode 100644
index 000000000..7e9c2cbc6
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/common.go
@@ -0,0 +1,476 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"crypto"
+	"crypto/rand"
+	"fmt"
+	"io"
+	"math"
+	"sync"
+
+	_ "crypto/sha1"
+	_ "crypto/sha256"
+	_ "crypto/sha512"
+)
+
+// These are string constants in the SSH protocol.
+const (
+	compressionNone = "none"
+	serviceUserAuth = "ssh-userauth"
+	serviceSSH      = "ssh-connection"
+)
+
+// supportedCiphers lists ciphers we support but might not recommend.
+var supportedCiphers = []string{
+	"aes128-ctr", "aes192-ctr", "aes256-ctr",
+	"aes128-gcm@openssh.com", gcm256CipherID,
+	chacha20Poly1305ID,
+	"arcfour256", "arcfour128", "arcfour",
+	aes128cbcID,
+	tripledescbcID,
+}
+
+// preferredCiphers specifies the default preference for ciphers.
+var preferredCiphers = []string{
+	"aes128-gcm@openssh.com", gcm256CipherID,
+	chacha20Poly1305ID,
+	"aes128-ctr", "aes192-ctr", "aes256-ctr",
+}
+
+// supportedKexAlgos specifies the supported key-exchange algorithms in
+// preference order.
+var supportedKexAlgos = []string{
+	kexAlgoCurve25519SHA256, kexAlgoCurve25519SHA256LibSSH,
+	// P384 and P521 are not constant-time yet, but since we don't
+	// reuse ephemeral keys, using them for ECDH should be OK.
+	kexAlgoECDH256, kexAlgoECDH384, kexAlgoECDH521,
+	kexAlgoDH14SHA256, kexAlgoDH16SHA512, kexAlgoDH14SHA1,
+	kexAlgoDH1SHA1,
+}
+
+// serverForbiddenKexAlgos contains key exchange algorithms, that are forbidden
+// for the server half.
+var serverForbiddenKexAlgos = map[string]struct{}{
+	kexAlgoDHGEXSHA1:   {}, // server half implementation is only minimal to satisfy the automated tests
+	kexAlgoDHGEXSHA256: {}, // server half implementation is only minimal to satisfy the automated tests
+}
+
+// preferredKexAlgos specifies the default preference for key-exchange
+// algorithms in preference order. The diffie-hellman-group16-sha512 algorithm
+// is disabled by default because it is a bit slower than the others.
+var preferredKexAlgos = []string{
+	kexAlgoCurve25519SHA256, kexAlgoCurve25519SHA256LibSSH,
+	kexAlgoECDH256, kexAlgoECDH384, kexAlgoECDH521,
+	kexAlgoDH14SHA256, kexAlgoDH14SHA1,
+}
+
+// supportedHostKeyAlgos specifies the supported host-key algorithms (i.e. methods
+// of authenticating servers) in preference order.
+var supportedHostKeyAlgos = []string{
+	CertAlgoRSASHA256v01, CertAlgoRSASHA512v01,
+	CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01,
+	CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoED25519v01,
+
+	KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521,
+	KeyAlgoRSASHA256, KeyAlgoRSASHA512,
+	KeyAlgoRSA, KeyAlgoDSA,
+
+	KeyAlgoED25519,
+}
+
+// supportedMACs specifies a default set of MAC algorithms in preference order.
+// This is based on RFC 4253, section 6.4, but with hmac-md5 variants removed
+// because they have reached the end of their useful life.
+var supportedMACs = []string{
+	"hmac-sha2-256-etm@openssh.com", "hmac-sha2-512-etm@openssh.com", "hmac-sha2-256", "hmac-sha2-512", "hmac-sha1", "hmac-sha1-96",
+}
+
+var supportedCompressions = []string{compressionNone}
+
+// hashFuncs keeps the mapping of supported signature algorithms to their
+// respective hashes needed for signing and verification.
+var hashFuncs = map[string]crypto.Hash{
+	KeyAlgoRSA:       crypto.SHA1,
+	KeyAlgoRSASHA256: crypto.SHA256,
+	KeyAlgoRSASHA512: crypto.SHA512,
+	KeyAlgoDSA:       crypto.SHA1,
+	KeyAlgoECDSA256:  crypto.SHA256,
+	KeyAlgoECDSA384:  crypto.SHA384,
+	KeyAlgoECDSA521:  crypto.SHA512,
+	// KeyAlgoED25519 doesn't pre-hash.
+	KeyAlgoSKECDSA256: crypto.SHA256,
+	KeyAlgoSKED25519:  crypto.SHA256,
+}
+
+// algorithmsForKeyFormat returns the supported signature algorithms for a given
+// public key format (PublicKey.Type), in order of preference. See RFC 8332,
+// Section 2. See also the note in sendKexInit on backwards compatibility.
+func algorithmsForKeyFormat(keyFormat string) []string {
+	switch keyFormat {
+	case KeyAlgoRSA:
+		return []string{KeyAlgoRSASHA256, KeyAlgoRSASHA512, KeyAlgoRSA}
+	case CertAlgoRSAv01:
+		return []string{CertAlgoRSASHA256v01, CertAlgoRSASHA512v01, CertAlgoRSAv01}
+	default:
+		return []string{keyFormat}
+	}
+}
+
+// isRSA returns whether algo is a supported RSA algorithm, including certificate
+// algorithms.
+func isRSA(algo string) bool {
+	algos := algorithmsForKeyFormat(KeyAlgoRSA)
+	return contains(algos, underlyingAlgo(algo))
+}
+
+func isRSACert(algo string) bool {
+	_, ok := certKeyAlgoNames[algo]
+	if !ok {
+		return false
+	}
+	return isRSA(algo)
+}
+
+// supportedPubKeyAuthAlgos specifies the supported client public key
+// authentication algorithms. Note that this doesn't include certificate types
+// since those use the underlying algorithm. This list is sent to the client if
+// it supports the server-sig-algs extension. Order is irrelevant.
+var supportedPubKeyAuthAlgos = []string{
+	KeyAlgoED25519,
+	KeyAlgoSKED25519, KeyAlgoSKECDSA256,
+	KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521,
+	KeyAlgoRSASHA256, KeyAlgoRSASHA512, KeyAlgoRSA,
+	KeyAlgoDSA,
+}
+
+// unexpectedMessageError results when the SSH message that we received didn't
+// match what we wanted.
+func unexpectedMessageError(expected, got uint8) error {
+	return fmt.Errorf("ssh: unexpected message type %d (expected %d)", got, expected)
+}
+
+// parseError results from a malformed SSH message.
+func parseError(tag uint8) error {
+	return fmt.Errorf("ssh: parse error in message type %d", tag)
+}
+
+func findCommon(what string, client []string, server []string) (common string, err error) {
+	for _, c := range client {
+		for _, s := range server {
+			if c == s {
+				return c, nil
+			}
+		}
+	}
+	return "", fmt.Errorf("ssh: no common algorithm for %s; client offered: %v, server offered: %v", what, client, server)
+}
+
+// directionAlgorithms records algorithm choices in one direction (either read or write)
+type directionAlgorithms struct {
+	Cipher      string
+	MAC         string
+	Compression string
+}
+
+// rekeyBytes returns a rekeying intervals in bytes.
+func (a *directionAlgorithms) rekeyBytes() int64 {
+	// According to RFC 4344 block ciphers should rekey after
+	// 2^(BLOCKSIZE/4) blocks. For all AES flavors BLOCKSIZE is
+	// 128.
+	switch a.Cipher {
+	case "aes128-ctr", "aes192-ctr", "aes256-ctr", gcm128CipherID, gcm256CipherID, aes128cbcID:
+		return 16 * (1 << 32)
+
+	}
+
+	// For others, stick with RFC 4253 recommendation to rekey after 1 Gb of data.
+	return 1 << 30
+}
+
+var aeadCiphers = map[string]bool{
+	gcm128CipherID:     true,
+	gcm256CipherID:     true,
+	chacha20Poly1305ID: true,
+}
+
+type algorithms struct {
+	kex     string
+	hostKey string
+	w       directionAlgorithms
+	r       directionAlgorithms
+}
+
+func findAgreedAlgorithms(isClient bool, clientKexInit, serverKexInit *kexInitMsg) (algs *algorithms, err error) {
+	result := &algorithms{}
+
+	result.kex, err = findCommon("key exchange", clientKexInit.KexAlgos, serverKexInit.KexAlgos)
+	if err != nil {
+		return
+	}
+
+	result.hostKey, err = findCommon("host key", clientKexInit.ServerHostKeyAlgos, serverKexInit.ServerHostKeyAlgos)
+	if err != nil {
+		return
+	}
+
+	stoc, ctos := &result.w, &result.r
+	if isClient {
+		ctos, stoc = stoc, ctos
+	}
+
+	ctos.Cipher, err = findCommon("client to server cipher", clientKexInit.CiphersClientServer, serverKexInit.CiphersClientServer)
+	if err != nil {
+		return
+	}
+
+	stoc.Cipher, err = findCommon("server to client cipher", clientKexInit.CiphersServerClient, serverKexInit.CiphersServerClient)
+	if err != nil {
+		return
+	}
+
+	if !aeadCiphers[ctos.Cipher] {
+		ctos.MAC, err = findCommon("client to server MAC", clientKexInit.MACsClientServer, serverKexInit.MACsClientServer)
+		if err != nil {
+			return
+		}
+	}
+
+	if !aeadCiphers[stoc.Cipher] {
+		stoc.MAC, err = findCommon("server to client MAC", clientKexInit.MACsServerClient, serverKexInit.MACsServerClient)
+		if err != nil {
+			return
+		}
+	}
+
+	ctos.Compression, err = findCommon("client to server compression", clientKexInit.CompressionClientServer, serverKexInit.CompressionClientServer)
+	if err != nil {
+		return
+	}
+
+	stoc.Compression, err = findCommon("server to client compression", clientKexInit.CompressionServerClient, serverKexInit.CompressionServerClient)
+	if err != nil {
+		return
+	}
+
+	return result, nil
+}
+
+// If rekeythreshold is too small, we can't make any progress sending
+// stuff.
+const minRekeyThreshold uint64 = 256
+
+// Config contains configuration data common to both ServerConfig and
+// ClientConfig.
+type Config struct {
+	// Rand provides the source of entropy for cryptographic
+	// primitives. If Rand is nil, the cryptographic random reader
+	// in package crypto/rand will be used.
+	Rand io.Reader
+
+	// The maximum number of bytes sent or received after which a
+	// new key is negotiated. It must be at least 256. If
+	// unspecified, a size suitable for the chosen cipher is used.
+	RekeyThreshold uint64
+
+	// The allowed key exchanges algorithms. If unspecified then a default set
+	// of algorithms is used. Unsupported values are silently ignored.
+	KeyExchanges []string
+
+	// The allowed cipher algorithms. If unspecified then a sensible default is
+	// used. Unsupported values are silently ignored.
+	Ciphers []string
+
+	// The allowed MAC algorithms. If unspecified then a sensible default is
+	// used. Unsupported values are silently ignored.
+	MACs []string
+}
+
+// SetDefaults sets sensible values for unset fields in config. This is
+// exported for testing: Configs passed to SSH functions are copied and have
+// default values set automatically.
+func (c *Config) SetDefaults() {
+	if c.Rand == nil {
+		c.Rand = rand.Reader
+	}
+	if c.Ciphers == nil {
+		c.Ciphers = preferredCiphers
+	}
+	var ciphers []string
+	for _, c := range c.Ciphers {
+		if cipherModes[c] != nil {
+			// Ignore the cipher if we have no cipherModes definition.
+			ciphers = append(ciphers, c)
+		}
+	}
+	c.Ciphers = ciphers
+
+	if c.KeyExchanges == nil {
+		c.KeyExchanges = preferredKexAlgos
+	}
+	var kexs []string
+	for _, k := range c.KeyExchanges {
+		if kexAlgoMap[k] != nil {
+			// Ignore the KEX if we have no kexAlgoMap definition.
+			kexs = append(kexs, k)
+		}
+	}
+	c.KeyExchanges = kexs
+
+	if c.MACs == nil {
+		c.MACs = supportedMACs
+	}
+	var macs []string
+	for _, m := range c.MACs {
+		if macModes[m] != nil {
+			// Ignore the MAC if we have no macModes definition.
+			macs = append(macs, m)
+		}
+	}
+	c.MACs = macs
+
+	if c.RekeyThreshold == 0 {
+		// cipher specific default
+	} else if c.RekeyThreshold < minRekeyThreshold {
+		c.RekeyThreshold = minRekeyThreshold
+	} else if c.RekeyThreshold >= math.MaxInt64 {
+		// Avoid weirdness if somebody uses -1 as a threshold.
+		c.RekeyThreshold = math.MaxInt64
+	}
+}
+
+// buildDataSignedForAuth returns the data that is signed in order to prove
+// possession of a private key. See RFC 4252, section 7. algo is the advertised
+// algorithm, and may be a certificate type.
+func buildDataSignedForAuth(sessionID []byte, req userAuthRequestMsg, algo string, pubKey []byte) []byte {
+	data := struct {
+		Session []byte
+		Type    byte
+		User    string
+		Service string
+		Method  string
+		Sign    bool
+		Algo    string
+		PubKey  []byte
+	}{
+		sessionID,
+		msgUserAuthRequest,
+		req.User,
+		req.Service,
+		req.Method,
+		true,
+		algo,
+		pubKey,
+	}
+	return Marshal(data)
+}
+
+func appendU16(buf []byte, n uint16) []byte {
+	return append(buf, byte(n>>8), byte(n))
+}
+
+func appendU32(buf []byte, n uint32) []byte {
+	return append(buf, byte(n>>24), byte(n>>16), byte(n>>8), byte(n))
+}
+
+func appendU64(buf []byte, n uint64) []byte {
+	return append(buf,
+		byte(n>>56), byte(n>>48), byte(n>>40), byte(n>>32),
+		byte(n>>24), byte(n>>16), byte(n>>8), byte(n))
+}
+
+func appendInt(buf []byte, n int) []byte {
+	return appendU32(buf, uint32(n))
+}
+
+func appendString(buf []byte, s string) []byte {
+	buf = appendU32(buf, uint32(len(s)))
+	buf = append(buf, s...)
+	return buf
+}
+
+func appendBool(buf []byte, b bool) []byte {
+	if b {
+		return append(buf, 1)
+	}
+	return append(buf, 0)
+}
+
+// newCond is a helper to hide the fact that there is no usable zero
+// value for sync.Cond.
+func newCond() *sync.Cond { return sync.NewCond(new(sync.Mutex)) }
+
+// window represents the buffer available to clients
+// wishing to write to a channel.
+type window struct {
+	*sync.Cond
+	win          uint32 // RFC 4254 5.2 says the window size can grow to 2^32-1
+	writeWaiters int
+	closed       bool
+}
+
+// add adds win to the amount of window available
+// for consumers.
+func (w *window) add(win uint32) bool {
+	// a zero sized window adjust is a noop.
+	if win == 0 {
+		return true
+	}
+	w.L.Lock()
+	if w.win+win < win {
+		w.L.Unlock()
+		return false
+	}
+	w.win += win
+	// It is unusual that multiple goroutines would be attempting to reserve
+	// window space, but not guaranteed. Use broadcast to notify all waiters
+	// that additional window is available.
+	w.Broadcast()
+	w.L.Unlock()
+	return true
+}
+
+// close sets the window to closed, so all reservations fail
+// immediately.
+func (w *window) close() {
+	w.L.Lock()
+	w.closed = true
+	w.Broadcast()
+	w.L.Unlock()
+}
+
+// reserve reserves win from the available window capacity.
+// If no capacity remains, reserve will block. reserve may
+// return less than requested.
+func (w *window) reserve(win uint32) (uint32, error) {
+	var err error
+	w.L.Lock()
+	w.writeWaiters++
+	w.Broadcast()
+	for w.win == 0 && !w.closed {
+		w.Wait()
+	}
+	w.writeWaiters--
+	if w.win < win {
+		win = w.win
+	}
+	w.win -= win
+	if w.closed {
+		err = io.EOF
+	}
+	w.L.Unlock()
+	return win, err
+}
+
+// waitWriterBlocked waits until some goroutine is blocked for further
+// writes. It is used in tests only.
+func (w *window) waitWriterBlocked() {
+	w.Cond.L.Lock()
+	for w.writeWaiters == 0 {
+		w.Cond.Wait()
+	}
+	w.Cond.L.Unlock()
+}
diff --git a/vendor/golang.org/x/crypto/ssh/connection.go b/vendor/golang.org/x/crypto/ssh/connection.go
new file mode 100644
index 000000000..8f345ee92
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/connection.go
@@ -0,0 +1,143 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"fmt"
+	"net"
+)
+
+// OpenChannelError is returned if the other side rejects an
+// OpenChannel request.
+type OpenChannelError struct {
+	Reason  RejectionReason
+	Message string
+}
+
+func (e *OpenChannelError) Error() string {
+	return fmt.Sprintf("ssh: rejected: %s (%s)", e.Reason, e.Message)
+}
+
+// ConnMetadata holds metadata for the connection.
+type ConnMetadata interface {
+	// User returns the user ID for this connection.
+	User() string
+
+	// SessionID returns the session hash, also denoted by H.
+	SessionID() []byte
+
+	// ClientVersion returns the client's version string as hashed
+	// into the session ID.
+	ClientVersion() []byte
+
+	// ServerVersion returns the server's version string as hashed
+	// into the session ID.
+	ServerVersion() []byte
+
+	// RemoteAddr returns the remote address for this connection.
+	RemoteAddr() net.Addr
+
+	// LocalAddr returns the local address for this connection.
+	LocalAddr() net.Addr
+}
+
+// Conn represents an SSH connection for both server and client roles.
+// Conn is the basis for implementing an application layer, such
+// as ClientConn, which implements the traditional shell access for
+// clients.
+type Conn interface {
+	ConnMetadata
+
+	// SendRequest sends a global request, and returns the
+	// reply. If wantReply is true, it returns the response status
+	// and payload. See also RFC 4254, section 4.
+	SendRequest(name string, wantReply bool, payload []byte) (bool, []byte, error)
+
+	// OpenChannel tries to open an channel. If the request is
+	// rejected, it returns *OpenChannelError. On success it returns
+	// the SSH Channel and a Go channel for incoming, out-of-band
+	// requests. The Go channel must be serviced, or the
+	// connection will hang.
+	OpenChannel(name string, data []byte) (Channel, <-chan *Request, error)
+
+	// Close closes the underlying network connection
+	Close() error
+
+	// Wait blocks until the connection has shut down, and returns the
+	// error causing the shutdown.
+	Wait() error
+
+	// TODO(hanwen): consider exposing:
+	//   RequestKeyChange
+	//   Disconnect
+}
+
+// DiscardRequests consumes and rejects all requests from the
+// passed-in channel.
+func DiscardRequests(in <-chan *Request) {
+	for req := range in {
+		if req.WantReply {
+			req.Reply(false, nil)
+		}
+	}
+}
+
+// A connection represents an incoming connection.
+type connection struct {
+	transport *handshakeTransport
+	sshConn
+
+	// The connection protocol.
+	*mux
+}
+
+func (c *connection) Close() error {
+	return c.sshConn.conn.Close()
+}
+
+// sshConn provides net.Conn metadata, but disallows direct reads and
+// writes.
+type sshConn struct {
+	conn net.Conn
+
+	user          string
+	sessionID     []byte
+	clientVersion []byte
+	serverVersion []byte
+}
+
+func dup(src []byte) []byte {
+	dst := make([]byte, len(src))
+	copy(dst, src)
+	return dst
+}
+
+func (c *sshConn) User() string {
+	return c.user
+}
+
+func (c *sshConn) RemoteAddr() net.Addr {
+	return c.conn.RemoteAddr()
+}
+
+func (c *sshConn) Close() error {
+	return c.conn.Close()
+}
+
+func (c *sshConn) LocalAddr() net.Addr {
+	return c.conn.LocalAddr()
+}
+
+func (c *sshConn) SessionID() []byte {
+	return dup(c.sessionID)
+}
+
+func (c *sshConn) ClientVersion() []byte {
+	return dup(c.clientVersion)
+}
+
+func (c *sshConn) ServerVersion() []byte {
+	return dup(c.serverVersion)
+}
diff --git a/vendor/golang.org/x/crypto/ssh/doc.go b/vendor/golang.org/x/crypto/ssh/doc.go
new file mode 100644
index 000000000..edbe63340
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/doc.go
@@ -0,0 +1,23 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package ssh implements an SSH client and server.
+
+SSH is a transport security protocol, an authentication protocol and a
+family of application protocols. The most typical application level
+protocol is a remote shell and this is specifically implemented.  However,
+the multiplexed nature of SSH is exposed to users that wish to support
+others.
+
+References:
+
+	[PROTOCOL]: https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL?rev=HEAD
+	[PROTOCOL.certkeys]: http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.certkeys?rev=HEAD
+	[SSH-PARAMETERS]:    http://www.iana.org/assignments/ssh-parameters/ssh-parameters.xml#ssh-parameters-1
+
+This package does not fall under the stability promise of the Go language itself,
+so its API may be changed when pressing needs arise.
+*/
+package ssh // import "golang.org/x/crypto/ssh"
diff --git a/vendor/golang.org/x/crypto/ssh/handshake.go b/vendor/golang.org/x/crypto/ssh/handshake.go
new file mode 100644
index 000000000..56cdc7c21
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/handshake.go
@@ -0,0 +1,806 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"strings"
+	"sync"
+)
+
+// debugHandshake, if set, prints messages sent and received.  Key
+// exchange messages are printed as if DH were used, so the debug
+// messages are wrong when using ECDH.
+const debugHandshake = false
+
+// chanSize sets the amount of buffering SSH connections. This is
+// primarily for testing: setting chanSize=0 uncovers deadlocks more
+// quickly.
+const chanSize = 16
+
+// keyingTransport is a packet based transport that supports key
+// changes. It need not be thread-safe. It should pass through
+// msgNewKeys in both directions.
+type keyingTransport interface {
+	packetConn
+
+	// prepareKeyChange sets up a key change. The key change for a
+	// direction will be effected if a msgNewKeys message is sent
+	// or received.
+	prepareKeyChange(*algorithms, *kexResult) error
+
+	// setStrictMode sets the strict KEX mode, notably triggering
+	// sequence number resets on sending or receiving msgNewKeys.
+	// If the sequence number is already > 1 when setStrictMode
+	// is called, an error is returned.
+	setStrictMode() error
+
+	// setInitialKEXDone indicates to the transport that the initial key exchange
+	// was completed
+	setInitialKEXDone()
+}
+
+// handshakeTransport implements rekeying on top of a keyingTransport
+// and offers a thread-safe writePacket() interface.
+type handshakeTransport struct {
+	conn   keyingTransport
+	config *Config
+
+	serverVersion []byte
+	clientVersion []byte
+
+	// hostKeys is non-empty if we are the server. In that case,
+	// it contains all host keys that can be used to sign the
+	// connection.
+	hostKeys []Signer
+
+	// publicKeyAuthAlgorithms is non-empty if we are the server. In that case,
+	// it contains the supported client public key authentication algorithms.
+	publicKeyAuthAlgorithms []string
+
+	// hostKeyAlgorithms is non-empty if we are the client. In that case,
+	// we accept these key types from the server as host key.
+	hostKeyAlgorithms []string
+
+	// On read error, incoming is closed, and readError is set.
+	incoming  chan []byte
+	readError error
+
+	mu               sync.Mutex
+	writeError       error
+	sentInitPacket   []byte
+	sentInitMsg      *kexInitMsg
+	pendingPackets   [][]byte // Used when a key exchange is in progress.
+	writePacketsLeft uint32
+	writeBytesLeft   int64
+
+	// If the read loop wants to schedule a kex, it pings this
+	// channel, and the write loop will send out a kex
+	// message.
+	requestKex chan struct{}
+
+	// If the other side requests or confirms a kex, its kexInit
+	// packet is sent here for the write loop to find it.
+	startKex    chan *pendingKex
+	kexLoopDone chan struct{} // closed (with writeError non-nil) when kexLoop exits
+
+	// data for host key checking
+	hostKeyCallback HostKeyCallback
+	dialAddress     string
+	remoteAddr      net.Addr
+
+	// bannerCallback is non-empty if we are the client and it has been set in
+	// ClientConfig. In that case it is called during the user authentication
+	// dance to handle a custom server's message.
+	bannerCallback BannerCallback
+
+	// Algorithms agreed in the last key exchange.
+	algorithms *algorithms
+
+	// Counters exclusively owned by readLoop.
+	readPacketsLeft uint32
+	readBytesLeft   int64
+
+	// The session ID or nil if first kex did not complete yet.
+	sessionID []byte
+
+	// strictMode indicates if the other side of the handshake indicated
+	// that we should be following the strict KEX protocol restrictions.
+	strictMode bool
+}
+
+type pendingKex struct {
+	otherInit []byte
+	done      chan error
+}
+
+func newHandshakeTransport(conn keyingTransport, config *Config, clientVersion, serverVersion []byte) *handshakeTransport {
+	t := &handshakeTransport{
+		conn:          conn,
+		serverVersion: serverVersion,
+		clientVersion: clientVersion,
+		incoming:      make(chan []byte, chanSize),
+		requestKex:    make(chan struct{}, 1),
+		startKex:      make(chan *pendingKex),
+		kexLoopDone:   make(chan struct{}),
+
+		config: config,
+	}
+	t.resetReadThresholds()
+	t.resetWriteThresholds()
+
+	// We always start with a mandatory key exchange.
+	t.requestKex <- struct{}{}
+	return t
+}
+
+func newClientTransport(conn keyingTransport, clientVersion, serverVersion []byte, config *ClientConfig, dialAddr string, addr net.Addr) *handshakeTransport {
+	t := newHandshakeTransport(conn, &config.Config, clientVersion, serverVersion)
+	t.dialAddress = dialAddr
+	t.remoteAddr = addr
+	t.hostKeyCallback = config.HostKeyCallback
+	t.bannerCallback = config.BannerCallback
+	if config.HostKeyAlgorithms != nil {
+		t.hostKeyAlgorithms = config.HostKeyAlgorithms
+	} else {
+		t.hostKeyAlgorithms = supportedHostKeyAlgos
+	}
+	go t.readLoop()
+	go t.kexLoop()
+	return t
+}
+
+func newServerTransport(conn keyingTransport, clientVersion, serverVersion []byte, config *ServerConfig) *handshakeTransport {
+	t := newHandshakeTransport(conn, &config.Config, clientVersion, serverVersion)
+	t.hostKeys = config.hostKeys
+	t.publicKeyAuthAlgorithms = config.PublicKeyAuthAlgorithms
+	go t.readLoop()
+	go t.kexLoop()
+	return t
+}
+
+func (t *handshakeTransport) getSessionID() []byte {
+	return t.sessionID
+}
+
+// waitSession waits for the session to be established. This should be
+// the first thing to call after instantiating handshakeTransport.
+func (t *handshakeTransport) waitSession() error {
+	p, err := t.readPacket()
+	if err != nil {
+		return err
+	}
+	if p[0] != msgNewKeys {
+		return fmt.Errorf("ssh: first packet should be msgNewKeys")
+	}
+
+	return nil
+}
+
+func (t *handshakeTransport) id() string {
+	if len(t.hostKeys) > 0 {
+		return "server"
+	}
+	return "client"
+}
+
+func (t *handshakeTransport) printPacket(p []byte, write bool) {
+	action := "got"
+	if write {
+		action = "sent"
+	}
+
+	if p[0] == msgChannelData || p[0] == msgChannelExtendedData {
+		log.Printf("%s %s data (packet %d bytes)", t.id(), action, len(p))
+	} else {
+		msg, err := decode(p)
+		log.Printf("%s %s %T %v (%v)", t.id(), action, msg, msg, err)
+	}
+}
+
+func (t *handshakeTransport) readPacket() ([]byte, error) {
+	p, ok := <-t.incoming
+	if !ok {
+		return nil, t.readError
+	}
+	return p, nil
+}
+
+func (t *handshakeTransport) readLoop() {
+	first := true
+	for {
+		p, err := t.readOnePacket(first)
+		first = false
+		if err != nil {
+			t.readError = err
+			close(t.incoming)
+			break
+		}
+		// If this is the first kex, and strict KEX mode is enabled,
+		// we don't ignore any messages, as they may be used to manipulate
+		// the packet sequence numbers.
+		if !(t.sessionID == nil && t.strictMode) && (p[0] == msgIgnore || p[0] == msgDebug) {
+			continue
+		}
+		t.incoming <- p
+	}
+
+	// Stop writers too.
+	t.recordWriteError(t.readError)
+
+	// Unblock the writer should it wait for this.
+	close(t.startKex)
+
+	// Don't close t.requestKex; it's also written to from writePacket.
+}
+
+func (t *handshakeTransport) pushPacket(p []byte) error {
+	if debugHandshake {
+		t.printPacket(p, true)
+	}
+	return t.conn.writePacket(p)
+}
+
+func (t *handshakeTransport) getWriteError() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.writeError
+}
+
+func (t *handshakeTransport) recordWriteError(err error) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.writeError == nil && err != nil {
+		t.writeError = err
+	}
+}
+
+func (t *handshakeTransport) requestKeyExchange() {
+	select {
+	case t.requestKex <- struct{}{}:
+	default:
+		// something already requested a kex, so do nothing.
+	}
+}
+
+func (t *handshakeTransport) resetWriteThresholds() {
+	t.writePacketsLeft = packetRekeyThreshold
+	if t.config.RekeyThreshold > 0 {
+		t.writeBytesLeft = int64(t.config.RekeyThreshold)
+	} else if t.algorithms != nil {
+		t.writeBytesLeft = t.algorithms.w.rekeyBytes()
+	} else {
+		t.writeBytesLeft = 1 << 30
+	}
+}
+
+func (t *handshakeTransport) kexLoop() {
+
+write:
+	for t.getWriteError() == nil {
+		var request *pendingKex
+		var sent bool
+
+		for request == nil || !sent {
+			var ok bool
+			select {
+			case request, ok = <-t.startKex:
+				if !ok {
+					break write
+				}
+			case <-t.requestKex:
+				break
+			}
+
+			if !sent {
+				if err := t.sendKexInit(); err != nil {
+					t.recordWriteError(err)
+					break
+				}
+				sent = true
+			}
+		}
+
+		if err := t.getWriteError(); err != nil {
+			if request != nil {
+				request.done <- err
+			}
+			break
+		}
+
+		// We're not servicing t.requestKex, but that is OK:
+		// we never block on sending to t.requestKex.
+
+		// We're not servicing t.startKex, but the remote end
+		// has just sent us a kexInitMsg, so it can't send
+		// another key change request, until we close the done
+		// channel on the pendingKex request.
+
+		err := t.enterKeyExchange(request.otherInit)
+
+		t.mu.Lock()
+		t.writeError = err
+		t.sentInitPacket = nil
+		t.sentInitMsg = nil
+
+		t.resetWriteThresholds()
+
+		// we have completed the key exchange. Since the
+		// reader is still blocked, it is safe to clear out
+		// the requestKex channel. This avoids the situation
+		// where: 1) we consumed our own request for the
+		// initial kex, and 2) the kex from the remote side
+		// caused another send on the requestKex channel,
+	clear:
+		for {
+			select {
+			case <-t.requestKex:
+				//
+			default:
+				break clear
+			}
+		}
+
+		request.done <- t.writeError
+
+		// kex finished. Push packets that we received while
+		// the kex was in progress. Don't look at t.startKex
+		// and don't increment writtenSinceKex: if we trigger
+		// another kex while we are still busy with the last
+		// one, things will become very confusing.
+		for _, p := range t.pendingPackets {
+			t.writeError = t.pushPacket(p)
+			if t.writeError != nil {
+				break
+			}
+		}
+		t.pendingPackets = t.pendingPackets[:0]
+		t.mu.Unlock()
+	}
+
+	// Unblock reader.
+	t.conn.Close()
+
+	// drain startKex channel. We don't service t.requestKex
+	// because nobody does blocking sends there.
+	for request := range t.startKex {
+		request.done <- t.getWriteError()
+	}
+
+	// Mark that the loop is done so that Close can return.
+	close(t.kexLoopDone)
+}
+
+// The protocol uses uint32 for packet counters, so we can't let them
+// reach 1<<32.  We will actually read and write more packets than
+// this, though: the other side may send more packets, and after we
+// hit this limit on writing we will send a few more packets for the
+// key exchange itself.
+const packetRekeyThreshold = (1 << 31)
+
+func (t *handshakeTransport) resetReadThresholds() {
+	t.readPacketsLeft = packetRekeyThreshold
+	if t.config.RekeyThreshold > 0 {
+		t.readBytesLeft = int64(t.config.RekeyThreshold)
+	} else if t.algorithms != nil {
+		t.readBytesLeft = t.algorithms.r.rekeyBytes()
+	} else {
+		t.readBytesLeft = 1 << 30
+	}
+}
+
+func (t *handshakeTransport) readOnePacket(first bool) ([]byte, error) {
+	p, err := t.conn.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	if t.readPacketsLeft > 0 {
+		t.readPacketsLeft--
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if t.readBytesLeft > 0 {
+		t.readBytesLeft -= int64(len(p))
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if debugHandshake {
+		t.printPacket(p, false)
+	}
+
+	if first && p[0] != msgKexInit {
+		return nil, fmt.Errorf("ssh: first packet should be msgKexInit")
+	}
+
+	if p[0] != msgKexInit {
+		return p, nil
+	}
+
+	firstKex := t.sessionID == nil
+
+	kex := pendingKex{
+		done:      make(chan error, 1),
+		otherInit: p,
+	}
+	t.startKex <- &kex
+	err = <-kex.done
+
+	if debugHandshake {
+		log.Printf("%s exited key exchange (first %v), err %v", t.id(), firstKex, err)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	t.resetReadThresholds()
+
+	// By default, a key exchange is hidden from higher layers by
+	// translating it into msgIgnore.
+	successPacket := []byte{msgIgnore}
+	if firstKex {
+		// sendKexInit() for the first kex waits for
+		// msgNewKeys so the authentication process is
+		// guaranteed to happen over an encrypted transport.
+		successPacket = []byte{msgNewKeys}
+	}
+
+	return successPacket, nil
+}
+
+const (
+	kexStrictClient = "kex-strict-c-v00@openssh.com"
+	kexStrictServer = "kex-strict-s-v00@openssh.com"
+)
+
+// sendKexInit sends a key change message.
+func (t *handshakeTransport) sendKexInit() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.sentInitMsg != nil {
+		// kexInits may be sent either in response to the other side,
+		// or because our side wants to initiate a key change, so we
+		// may have already sent a kexInit. In that case, don't send a
+		// second kexInit.
+		return nil
+	}
+
+	msg := &kexInitMsg{
+		CiphersClientServer:     t.config.Ciphers,
+		CiphersServerClient:     t.config.Ciphers,
+		MACsClientServer:        t.config.MACs,
+		MACsServerClient:        t.config.MACs,
+		CompressionClientServer: supportedCompressions,
+		CompressionServerClient: supportedCompressions,
+	}
+	io.ReadFull(rand.Reader, msg.Cookie[:])
+
+	// We mutate the KexAlgos slice, in order to add the kex-strict extension algorithm,
+	// and possibly to add the ext-info extension algorithm. Since the slice may be the
+	// user owned KeyExchanges, we create our own slice in order to avoid using user
+	// owned memory by mistake.
+	msg.KexAlgos = make([]string, 0, len(t.config.KeyExchanges)+2) // room for kex-strict and ext-info
+	msg.KexAlgos = append(msg.KexAlgos, t.config.KeyExchanges...)
+
+	isServer := len(t.hostKeys) > 0
+	if isServer {
+		for _, k := range t.hostKeys {
+			// If k is a MultiAlgorithmSigner, we restrict the signature
+			// algorithms. If k is a AlgorithmSigner, presume it supports all
+			// signature algorithms associated with the key format. If k is not
+			// an AlgorithmSigner, we can only assume it only supports the
+			// algorithms that matches the key format. (This means that Sign
+			// can't pick a different default).
+			keyFormat := k.PublicKey().Type()
+
+			switch s := k.(type) {
+			case MultiAlgorithmSigner:
+				for _, algo := range algorithmsForKeyFormat(keyFormat) {
+					if contains(s.Algorithms(), underlyingAlgo(algo)) {
+						msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algo)
+					}
+				}
+			case AlgorithmSigner:
+				msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algorithmsForKeyFormat(keyFormat)...)
+			default:
+				msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, keyFormat)
+			}
+		}
+
+		if t.sessionID == nil {
+			msg.KexAlgos = append(msg.KexAlgos, kexStrictServer)
+		}
+	} else {
+		msg.ServerHostKeyAlgos = t.hostKeyAlgorithms
+
+		// As a client we opt in to receiving SSH_MSG_EXT_INFO so we know what
+		// algorithms the server supports for public key authentication. See RFC
+		// 8308, Section 2.1.
+		//
+		// We also send the strict KEX mode extension algorithm, in order to opt
+		// into the strict KEX mode.
+		if firstKeyExchange := t.sessionID == nil; firstKeyExchange {
+			msg.KexAlgos = append(msg.KexAlgos, "ext-info-c")
+			msg.KexAlgos = append(msg.KexAlgos, kexStrictClient)
+		}
+
+	}
+
+	packet := Marshal(msg)
+
+	// writePacket destroys the contents, so save a copy.
+	packetCopy := make([]byte, len(packet))
+	copy(packetCopy, packet)
+
+	if err := t.pushPacket(packetCopy); err != nil {
+		return err
+	}
+
+	t.sentInitMsg = msg
+	t.sentInitPacket = packet
+
+	return nil
+}
+
+func (t *handshakeTransport) writePacket(p []byte) error {
+	switch p[0] {
+	case msgKexInit:
+		return errors.New("ssh: only handshakeTransport can send kexInit")
+	case msgNewKeys:
+		return errors.New("ssh: only handshakeTransport can send newKeys")
+	}
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.writeError != nil {
+		return t.writeError
+	}
+
+	if t.sentInitMsg != nil {
+		// Copy the packet so the writer can reuse the buffer.
+		cp := make([]byte, len(p))
+		copy(cp, p)
+		t.pendingPackets = append(t.pendingPackets, cp)
+		return nil
+	}
+
+	if t.writeBytesLeft > 0 {
+		t.writeBytesLeft -= int64(len(p))
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if t.writePacketsLeft > 0 {
+		t.writePacketsLeft--
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if err := t.pushPacket(p); err != nil {
+		t.writeError = err
+	}
+
+	return nil
+}
+
+func (t *handshakeTransport) Close() error {
+	// Close the connection. This should cause the readLoop goroutine to wake up
+	// and close t.startKex, which will shut down kexLoop if running.
+	err := t.conn.Close()
+
+	// Wait for the kexLoop goroutine to complete.
+	// At that point we know that the readLoop goroutine is complete too,
+	// because kexLoop itself waits for readLoop to close the startKex channel.
+	<-t.kexLoopDone
+
+	return err
+}
+
+func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
+	if debugHandshake {
+		log.Printf("%s entered key exchange", t.id())
+	}
+
+	otherInit := &kexInitMsg{}
+	if err := Unmarshal(otherInitPacket, otherInit); err != nil {
+		return err
+	}
+
+	magics := handshakeMagics{
+		clientVersion: t.clientVersion,
+		serverVersion: t.serverVersion,
+		clientKexInit: otherInitPacket,
+		serverKexInit: t.sentInitPacket,
+	}
+
+	clientInit := otherInit
+	serverInit := t.sentInitMsg
+	isClient := len(t.hostKeys) == 0
+	if isClient {
+		clientInit, serverInit = serverInit, clientInit
+
+		magics.clientKexInit = t.sentInitPacket
+		magics.serverKexInit = otherInitPacket
+	}
+
+	var err error
+	t.algorithms, err = findAgreedAlgorithms(isClient, clientInit, serverInit)
+	if err != nil {
+		return err
+	}
+
+	if t.sessionID == nil && ((isClient && contains(serverInit.KexAlgos, kexStrictServer)) || (!isClient && contains(clientInit.KexAlgos, kexStrictClient))) {
+		t.strictMode = true
+		if err := t.conn.setStrictMode(); err != nil {
+			return err
+		}
+	}
+
+	// We don't send FirstKexFollows, but we handle receiving it.
+	//
+	// RFC 4253 section 7 defines the kex and the agreement method for
+	// first_kex_packet_follows. It states that the guessed packet
+	// should be ignored if the "kex algorithm and/or the host
+	// key algorithm is guessed wrong (server and client have
+	// different preferred algorithm), or if any of the other
+	// algorithms cannot be agreed upon". The other algorithms have
+	// already been checked above so the kex algorithm and host key
+	// algorithm are checked here.
+	if otherInit.FirstKexFollows && (clientInit.KexAlgos[0] != serverInit.KexAlgos[0] || clientInit.ServerHostKeyAlgos[0] != serverInit.ServerHostKeyAlgos[0]) {
+		// other side sent a kex message for the wrong algorithm,
+		// which we have to ignore.
+		if _, err := t.conn.readPacket(); err != nil {
+			return err
+		}
+	}
+
+	kex, ok := kexAlgoMap[t.algorithms.kex]
+	if !ok {
+		return fmt.Errorf("ssh: unexpected key exchange algorithm %v", t.algorithms.kex)
+	}
+
+	var result *kexResult
+	if len(t.hostKeys) > 0 {
+		result, err = t.server(kex, &magics)
+	} else {
+		result, err = t.client(kex, &magics)
+	}
+
+	if err != nil {
+		return err
+	}
+
+	firstKeyExchange := t.sessionID == nil
+	if firstKeyExchange {
+		t.sessionID = result.H
+	}
+	result.SessionID = t.sessionID
+
+	if err := t.conn.prepareKeyChange(t.algorithms, result); err != nil {
+		return err
+	}
+	if err = t.conn.writePacket([]byte{msgNewKeys}); err != nil {
+		return err
+	}
+
+	// On the server side, after the first SSH_MSG_NEWKEYS, send a SSH_MSG_EXT_INFO
+	// message with the server-sig-algs extension if the client supports it. See
+	// RFC 8308, Sections 2.4 and 3.1, and [PROTOCOL], Section 1.9.
+	if !isClient && firstKeyExchange && contains(clientInit.KexAlgos, "ext-info-c") {
+		supportedPubKeyAuthAlgosList := strings.Join(t.publicKeyAuthAlgorithms, ",")
+		extInfo := &extInfoMsg{
+			NumExtensions: 2,
+			Payload:       make([]byte, 0, 4+15+4+len(supportedPubKeyAuthAlgosList)+4+16+4+1),
+		}
+		extInfo.Payload = appendInt(extInfo.Payload, len("server-sig-algs"))
+		extInfo.Payload = append(extInfo.Payload, "server-sig-algs"...)
+		extInfo.Payload = appendInt(extInfo.Payload, len(supportedPubKeyAuthAlgosList))
+		extInfo.Payload = append(extInfo.Payload, supportedPubKeyAuthAlgosList...)
+		extInfo.Payload = appendInt(extInfo.Payload, len("ping@openssh.com"))
+		extInfo.Payload = append(extInfo.Payload, "ping@openssh.com"...)
+		extInfo.Payload = appendInt(extInfo.Payload, 1)
+		extInfo.Payload = append(extInfo.Payload, "0"...)
+		if err := t.conn.writePacket(Marshal(extInfo)); err != nil {
+			return err
+		}
+	}
+
+	if packet, err := t.conn.readPacket(); err != nil {
+		return err
+	} else if packet[0] != msgNewKeys {
+		return unexpectedMessageError(msgNewKeys, packet[0])
+	}
+
+	if firstKeyExchange {
+		// Indicates to the transport that the first key exchange is completed
+		// after receiving SSH_MSG_NEWKEYS.
+		t.conn.setInitialKEXDone()
+	}
+
+	return nil
+}
+
+// algorithmSignerWrapper is an AlgorithmSigner that only supports the default
+// key format algorithm.
+//
+// This is technically a violation of the AlgorithmSigner interface, but it
+// should be unreachable given where we use this. Anyway, at least it returns an
+// error instead of panicing or producing an incorrect signature.
+type algorithmSignerWrapper struct {
+	Signer
+}
+
+func (a algorithmSignerWrapper) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
+	if algorithm != underlyingAlgo(a.PublicKey().Type()) {
+		return nil, errors.New("ssh: internal error: algorithmSignerWrapper invoked with non-default algorithm")
+	}
+	return a.Sign(rand, data)
+}
+
+func pickHostKey(hostKeys []Signer, algo string) AlgorithmSigner {
+	for _, k := range hostKeys {
+		if s, ok := k.(MultiAlgorithmSigner); ok {
+			if !contains(s.Algorithms(), underlyingAlgo(algo)) {
+				continue
+			}
+		}
+
+		if algo == k.PublicKey().Type() {
+			return algorithmSignerWrapper{k}
+		}
+
+		k, ok := k.(AlgorithmSigner)
+		if !ok {
+			continue
+		}
+		for _, a := range algorithmsForKeyFormat(k.PublicKey().Type()) {
+			if algo == a {
+				return k
+			}
+		}
+	}
+	return nil
+}
+
+func (t *handshakeTransport) server(kex kexAlgorithm, magics *handshakeMagics) (*kexResult, error) {
+	hostKey := pickHostKey(t.hostKeys, t.algorithms.hostKey)
+	if hostKey == nil {
+		return nil, errors.New("ssh: internal error: negotiated unsupported signature type")
+	}
+
+	r, err := kex.Server(t.conn, t.config.Rand, magics, hostKey, t.algorithms.hostKey)
+	return r, err
+}
+
+func (t *handshakeTransport) client(kex kexAlgorithm, magics *handshakeMagics) (*kexResult, error) {
+	result, err := kex.Client(t.conn, t.config.Rand, magics)
+	if err != nil {
+		return nil, err
+	}
+
+	hostKey, err := ParsePublicKey(result.HostKey)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := verifyHostKeySignature(hostKey, t.algorithms.hostKey, result); err != nil {
+		return nil, err
+	}
+
+	err = t.hostKeyCallback(t.dialAddress, t.remoteAddr, hostKey)
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
diff --git a/vendor/golang.org/x/crypto/ssh/internal/bcrypt_pbkdf/bcrypt_pbkdf.go b/vendor/golang.org/x/crypto/ssh/internal/bcrypt_pbkdf/bcrypt_pbkdf.go
new file mode 100644
index 000000000..af81d2665
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/internal/bcrypt_pbkdf/bcrypt_pbkdf.go
@@ -0,0 +1,93 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package bcrypt_pbkdf implements bcrypt_pbkdf(3) from OpenBSD.
+//
+// See https://flak.tedunangst.com/post/bcrypt-pbkdf and
+// https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libutil/bcrypt_pbkdf.c.
+package bcrypt_pbkdf
+
+import (
+	"crypto/sha512"
+	"errors"
+	"golang.org/x/crypto/blowfish"
+)
+
+const blockSize = 32
+
+// Key derives a key from the password, salt and rounds count, returning a
+// []byte of length keyLen that can be used as cryptographic key.
+func Key(password, salt []byte, rounds, keyLen int) ([]byte, error) {
+	if rounds < 1 {
+		return nil, errors.New("bcrypt_pbkdf: number of rounds is too small")
+	}
+	if len(password) == 0 {
+		return nil, errors.New("bcrypt_pbkdf: empty password")
+	}
+	if len(salt) == 0 || len(salt) > 1<<20 {
+		return nil, errors.New("bcrypt_pbkdf: bad salt length")
+	}
+	if keyLen > 1024 {
+		return nil, errors.New("bcrypt_pbkdf: keyLen is too large")
+	}
+
+	numBlocks := (keyLen + blockSize - 1) / blockSize
+	key := make([]byte, numBlocks*blockSize)
+
+	h := sha512.New()
+	h.Write(password)
+	shapass := h.Sum(nil)
+
+	shasalt := make([]byte, 0, sha512.Size)
+	cnt, tmp := make([]byte, 4), make([]byte, blockSize)
+	for block := 1; block <= numBlocks; block++ {
+		h.Reset()
+		h.Write(salt)
+		cnt[0] = byte(block >> 24)
+		cnt[1] = byte(block >> 16)
+		cnt[2] = byte(block >> 8)
+		cnt[3] = byte(block)
+		h.Write(cnt)
+		bcryptHash(tmp, shapass, h.Sum(shasalt))
+
+		out := make([]byte, blockSize)
+		copy(out, tmp)
+		for i := 2; i <= rounds; i++ {
+			h.Reset()
+			h.Write(tmp)
+			bcryptHash(tmp, shapass, h.Sum(shasalt))
+			for j := 0; j < len(out); j++ {
+				out[j] ^= tmp[j]
+			}
+		}
+
+		for i, v := range out {
+			key[i*numBlocks+(block-1)] = v
+		}
+	}
+	return key[:keyLen], nil
+}
+
+var magic = []byte("OxychromaticBlowfishSwatDynamite")
+
+func bcryptHash(out, shapass, shasalt []byte) {
+	c, err := blowfish.NewSaltedCipher(shapass, shasalt)
+	if err != nil {
+		panic(err)
+	}
+	for i := 0; i < 64; i++ {
+		blowfish.ExpandKey(shasalt, c)
+		blowfish.ExpandKey(shapass, c)
+	}
+	copy(out, magic)
+	for i := 0; i < 32; i += 8 {
+		for j := 0; j < 64; j++ {
+			c.Encrypt(out[i:i+8], out[i:i+8])
+		}
+	}
+	// Swap bytes due to different endianness.
+	for i := 0; i < 32; i += 4 {
+		out[i+3], out[i+2], out[i+1], out[i] = out[i], out[i+1], out[i+2], out[i+3]
+	}
+}
diff --git a/vendor/golang.org/x/crypto/ssh/kex.go b/vendor/golang.org/x/crypto/ssh/kex.go
new file mode 100644
index 000000000..8a05f7990
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/kex.go
@@ -0,0 +1,786 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/subtle"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math/big"
+
+	"golang.org/x/crypto/curve25519"
+)
+
+const (
+	kexAlgoDH1SHA1                = "diffie-hellman-group1-sha1"
+	kexAlgoDH14SHA1               = "diffie-hellman-group14-sha1"
+	kexAlgoDH14SHA256             = "diffie-hellman-group14-sha256"
+	kexAlgoDH16SHA512             = "diffie-hellman-group16-sha512"
+	kexAlgoECDH256                = "ecdh-sha2-nistp256"
+	kexAlgoECDH384                = "ecdh-sha2-nistp384"
+	kexAlgoECDH521                = "ecdh-sha2-nistp521"
+	kexAlgoCurve25519SHA256LibSSH = "curve25519-sha256@libssh.org"
+	kexAlgoCurve25519SHA256       = "curve25519-sha256"
+
+	// For the following kex only the client half contains a production
+	// ready implementation. The server half only consists of a minimal
+	// implementation to satisfy the automated tests.
+	kexAlgoDHGEXSHA1   = "diffie-hellman-group-exchange-sha1"
+	kexAlgoDHGEXSHA256 = "diffie-hellman-group-exchange-sha256"
+)
+
+// kexResult captures the outcome of a key exchange.
+type kexResult struct {
+	// Session hash. See also RFC 4253, section 8.
+	H []byte
+
+	// Shared secret. See also RFC 4253, section 8.
+	K []byte
+
+	// Host key as hashed into H.
+	HostKey []byte
+
+	// Signature of H.
+	Signature []byte
+
+	// A cryptographic hash function that matches the security
+	// level of the key exchange algorithm. It is used for
+	// calculating H, and for deriving keys from H and K.
+	Hash crypto.Hash
+
+	// The session ID, which is the first H computed. This is used
+	// to derive key material inside the transport.
+	SessionID []byte
+}
+
+// handshakeMagics contains data that is always included in the
+// session hash.
+type handshakeMagics struct {
+	clientVersion, serverVersion []byte
+	clientKexInit, serverKexInit []byte
+}
+
+func (m *handshakeMagics) write(w io.Writer) {
+	writeString(w, m.clientVersion)
+	writeString(w, m.serverVersion)
+	writeString(w, m.clientKexInit)
+	writeString(w, m.serverKexInit)
+}
+
+// kexAlgorithm abstracts different key exchange algorithms.
+type kexAlgorithm interface {
+	// Server runs server-side key agreement, signing the result
+	// with a hostkey. algo is the negotiated algorithm, and may
+	// be a certificate type.
+	Server(p packetConn, rand io.Reader, magics *handshakeMagics, s AlgorithmSigner, algo string) (*kexResult, error)
+
+	// Client runs the client-side key agreement. Caller is
+	// responsible for verifying the host key signature.
+	Client(p packetConn, rand io.Reader, magics *handshakeMagics) (*kexResult, error)
+}
+
+// dhGroup is a multiplicative group suitable for implementing Diffie-Hellman key agreement.
+type dhGroup struct {
+	g, p, pMinus1 *big.Int
+	hashFunc      crypto.Hash
+}
+
+func (group *dhGroup) diffieHellman(theirPublic, myPrivate *big.Int) (*big.Int, error) {
+	if theirPublic.Cmp(bigOne) <= 0 || theirPublic.Cmp(group.pMinus1) >= 0 {
+		return nil, errors.New("ssh: DH parameter out of bounds")
+	}
+	return new(big.Int).Exp(theirPublic, myPrivate, group.p), nil
+}
+
+func (group *dhGroup) Client(c packetConn, randSource io.Reader, magics *handshakeMagics) (*kexResult, error) {
+	var x *big.Int
+	for {
+		var err error
+		if x, err = rand.Int(randSource, group.pMinus1); err != nil {
+			return nil, err
+		}
+		if x.Sign() > 0 {
+			break
+		}
+	}
+
+	X := new(big.Int).Exp(group.g, x, group.p)
+	kexDHInit := kexDHInitMsg{
+		X: X,
+	}
+	if err := c.writePacket(Marshal(&kexDHInit)); err != nil {
+		return nil, err
+	}
+
+	packet, err := c.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	var kexDHReply kexDHReplyMsg
+	if err = Unmarshal(packet, &kexDHReply); err != nil {
+		return nil, err
+	}
+
+	ki, err := group.diffieHellman(kexDHReply.Y, x)
+	if err != nil {
+		return nil, err
+	}
+
+	h := group.hashFunc.New()
+	magics.write(h)
+	writeString(h, kexDHReply.HostKey)
+	writeInt(h, X)
+	writeInt(h, kexDHReply.Y)
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
+	h.Write(K)
+
+	return &kexResult{
+		H:         h.Sum(nil),
+		K:         K,
+		HostKey:   kexDHReply.HostKey,
+		Signature: kexDHReply.Signature,
+		Hash:      group.hashFunc,
+	}, nil
+}
+
+func (group *dhGroup) Server(c packetConn, randSource io.Reader, magics *handshakeMagics, priv AlgorithmSigner, algo string) (result *kexResult, err error) {
+	packet, err := c.readPacket()
+	if err != nil {
+		return
+	}
+	var kexDHInit kexDHInitMsg
+	if err = Unmarshal(packet, &kexDHInit); err != nil {
+		return
+	}
+
+	var y *big.Int
+	for {
+		if y, err = rand.Int(randSource, group.pMinus1); err != nil {
+			return
+		}
+		if y.Sign() > 0 {
+			break
+		}
+	}
+
+	Y := new(big.Int).Exp(group.g, y, group.p)
+	ki, err := group.diffieHellman(kexDHInit.X, y)
+	if err != nil {
+		return nil, err
+	}
+
+	hostKeyBytes := priv.PublicKey().Marshal()
+
+	h := group.hashFunc.New()
+	magics.write(h)
+	writeString(h, hostKeyBytes)
+	writeInt(h, kexDHInit.X)
+	writeInt(h, Y)
+
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
+	h.Write(K)
+
+	H := h.Sum(nil)
+
+	// H is already a hash, but the hostkey signing will apply its
+	// own key-specific hash algorithm.
+	sig, err := signAndMarshal(priv, randSource, H, algo)
+	if err != nil {
+		return nil, err
+	}
+
+	kexDHReply := kexDHReplyMsg{
+		HostKey:   hostKeyBytes,
+		Y:         Y,
+		Signature: sig,
+	}
+	packet = Marshal(&kexDHReply)
+
+	err = c.writePacket(packet)
+	return &kexResult{
+		H:         H,
+		K:         K,
+		HostKey:   hostKeyBytes,
+		Signature: sig,
+		Hash:      group.hashFunc,
+	}, err
+}
+
+// ecdh performs Elliptic Curve Diffie-Hellman key exchange as
+// described in RFC 5656, section 4.
+type ecdh struct {
+	curve elliptic.Curve
+}
+
+func (kex *ecdh) Client(c packetConn, rand io.Reader, magics *handshakeMagics) (*kexResult, error) {
+	ephKey, err := ecdsa.GenerateKey(kex.curve, rand)
+	if err != nil {
+		return nil, err
+	}
+
+	kexInit := kexECDHInitMsg{
+		ClientPubKey: elliptic.Marshal(kex.curve, ephKey.PublicKey.X, ephKey.PublicKey.Y),
+	}
+
+	serialized := Marshal(&kexInit)
+	if err := c.writePacket(serialized); err != nil {
+		return nil, err
+	}
+
+	packet, err := c.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	var reply kexECDHReplyMsg
+	if err = Unmarshal(packet, &reply); err != nil {
+		return nil, err
+	}
+
+	x, y, err := unmarshalECKey(kex.curve, reply.EphemeralPubKey)
+	if err != nil {
+		return nil, err
+	}
+
+	// generate shared secret
+	secret, _ := kex.curve.ScalarMult(x, y, ephKey.D.Bytes())
+
+	h := ecHash(kex.curve).New()
+	magics.write(h)
+	writeString(h, reply.HostKey)
+	writeString(h, kexInit.ClientPubKey)
+	writeString(h, reply.EphemeralPubKey)
+	K := make([]byte, intLength(secret))
+	marshalInt(K, secret)
+	h.Write(K)
+
+	return &kexResult{
+		H:         h.Sum(nil),
+		K:         K,
+		HostKey:   reply.HostKey,
+		Signature: reply.Signature,
+		Hash:      ecHash(kex.curve),
+	}, nil
+}
+
+// unmarshalECKey parses and checks an EC key.
+func unmarshalECKey(curve elliptic.Curve, pubkey []byte) (x, y *big.Int, err error) {
+	x, y = elliptic.Unmarshal(curve, pubkey)
+	if x == nil {
+		return nil, nil, errors.New("ssh: elliptic.Unmarshal failure")
+	}
+	if !validateECPublicKey(curve, x, y) {
+		return nil, nil, errors.New("ssh: public key not on curve")
+	}
+	return x, y, nil
+}
+
+// validateECPublicKey checks that the point is a valid public key for
+// the given curve. See [SEC1], 3.2.2
+func validateECPublicKey(curve elliptic.Curve, x, y *big.Int) bool {
+	if x.Sign() == 0 && y.Sign() == 0 {
+		return false
+	}
+
+	if x.Cmp(curve.Params().P) >= 0 {
+		return false
+	}
+
+	if y.Cmp(curve.Params().P) >= 0 {
+		return false
+	}
+
+	if !curve.IsOnCurve(x, y) {
+		return false
+	}
+
+	// We don't check if N * PubKey == 0, since
+	//
+	// - the NIST curves have cofactor = 1, so this is implicit.
+	// (We don't foresee an implementation that supports non NIST
+	// curves)
+	//
+	// - for ephemeral keys, we don't need to worry about small
+	// subgroup attacks.
+	return true
+}
+
+func (kex *ecdh) Server(c packetConn, rand io.Reader, magics *handshakeMagics, priv AlgorithmSigner, algo string) (result *kexResult, err error) {
+	packet, err := c.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	var kexECDHInit kexECDHInitMsg
+	if err = Unmarshal(packet, &kexECDHInit); err != nil {
+		return nil, err
+	}
+
+	clientX, clientY, err := unmarshalECKey(kex.curve, kexECDHInit.ClientPubKey)
+	if err != nil {
+		return nil, err
+	}
+
+	// We could cache this key across multiple users/multiple
+	// connection attempts, but the benefit is small. OpenSSH
+	// generates a new key for each incoming connection.
+	ephKey, err := ecdsa.GenerateKey(kex.curve, rand)
+	if err != nil {
+		return nil, err
+	}
+
+	hostKeyBytes := priv.PublicKey().Marshal()
+
+	serializedEphKey := elliptic.Marshal(kex.curve, ephKey.PublicKey.X, ephKey.PublicKey.Y)
+
+	// generate shared secret
+	secret, _ := kex.curve.ScalarMult(clientX, clientY, ephKey.D.Bytes())
+
+	h := ecHash(kex.curve).New()
+	magics.write(h)
+	writeString(h, hostKeyBytes)
+	writeString(h, kexECDHInit.ClientPubKey)
+	writeString(h, serializedEphKey)
+
+	K := make([]byte, intLength(secret))
+	marshalInt(K, secret)
+	h.Write(K)
+
+	H := h.Sum(nil)
+
+	// H is already a hash, but the hostkey signing will apply its
+	// own key-specific hash algorithm.
+	sig, err := signAndMarshal(priv, rand, H, algo)
+	if err != nil {
+		return nil, err
+	}
+
+	reply := kexECDHReplyMsg{
+		EphemeralPubKey: serializedEphKey,
+		HostKey:         hostKeyBytes,
+		Signature:       sig,
+	}
+
+	serialized := Marshal(&reply)
+	if err := c.writePacket(serialized); err != nil {
+		return nil, err
+	}
+
+	return &kexResult{
+		H:         H,
+		K:         K,
+		HostKey:   reply.HostKey,
+		Signature: sig,
+		Hash:      ecHash(kex.curve),
+	}, nil
+}
+
+// ecHash returns the hash to match the given elliptic curve, see RFC
+// 5656, section 6.2.1
+func ecHash(curve elliptic.Curve) crypto.Hash {
+	bitSize := curve.Params().BitSize
+	switch {
+	case bitSize <= 256:
+		return crypto.SHA256
+	case bitSize <= 384:
+		return crypto.SHA384
+	}
+	return crypto.SHA512
+}
+
+var kexAlgoMap = map[string]kexAlgorithm{}
+
+func init() {
+	// This is the group called diffie-hellman-group1-sha1 in
+	// RFC 4253 and Oakley Group 2 in RFC 2409.
+	p, _ := new(big.Int).SetString("FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF", 16)
+	kexAlgoMap[kexAlgoDH1SHA1] = &dhGroup{
+		g:        new(big.Int).SetInt64(2),
+		p:        p,
+		pMinus1:  new(big.Int).Sub(p, bigOne),
+		hashFunc: crypto.SHA1,
+	}
+
+	// This are the groups called diffie-hellman-group14-sha1 and
+	// diffie-hellman-group14-sha256 in RFC 4253 and RFC 8268,
+	// and Oakley Group 14 in RFC 3526.
+	p, _ = new(big.Int).SetString("FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB9ED529077096966D670C354E4ABC9804F1746C08CA18217C32905E462E36CE3BE39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF6955817183995497CEA956AE515D2261898FA051015728E5A8AACAA68FFFFFFFFFFFFFFFF", 16)
+	group14 := &dhGroup{
+		g:       new(big.Int).SetInt64(2),
+		p:       p,
+		pMinus1: new(big.Int).Sub(p, bigOne),
+	}
+
+	kexAlgoMap[kexAlgoDH14SHA1] = &dhGroup{
+		g: group14.g, p: group14.p, pMinus1: group14.pMinus1,
+		hashFunc: crypto.SHA1,
+	}
+	kexAlgoMap[kexAlgoDH14SHA256] = &dhGroup{
+		g: group14.g, p: group14.p, pMinus1: group14.pMinus1,
+		hashFunc: crypto.SHA256,
+	}
+
+	// This is the group called diffie-hellman-group16-sha512 in RFC
+	// 8268 and Oakley Group 16 in RFC 3526.
+	p, _ = new(big.Int).SetString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
+
+	kexAlgoMap[kexAlgoDH16SHA512] = &dhGroup{
+		g:        new(big.Int).SetInt64(2),
+		p:        p,
+		pMinus1:  new(big.Int).Sub(p, bigOne),
+		hashFunc: crypto.SHA512,
+	}
+
+	kexAlgoMap[kexAlgoECDH521] = &ecdh{elliptic.P521()}
+	kexAlgoMap[kexAlgoECDH384] = &ecdh{elliptic.P384()}
+	kexAlgoMap[kexAlgoECDH256] = &ecdh{elliptic.P256()}
+	kexAlgoMap[kexAlgoCurve25519SHA256] = &curve25519sha256{}
+	kexAlgoMap[kexAlgoCurve25519SHA256LibSSH] = &curve25519sha256{}
+	kexAlgoMap[kexAlgoDHGEXSHA1] = &dhGEXSHA{hashFunc: crypto.SHA1}
+	kexAlgoMap[kexAlgoDHGEXSHA256] = &dhGEXSHA{hashFunc: crypto.SHA256}
+}
+
+// curve25519sha256 implements the curve25519-sha256 (formerly known as
+// curve25519-sha256@libssh.org) key exchange method, as described in RFC 8731.
+type curve25519sha256 struct{}
+
+type curve25519KeyPair struct {
+	priv [32]byte
+	pub  [32]byte
+}
+
+func (kp *curve25519KeyPair) generate(rand io.Reader) error {
+	if _, err := io.ReadFull(rand, kp.priv[:]); err != nil {
+		return err
+	}
+	curve25519.ScalarBaseMult(&kp.pub, &kp.priv)
+	return nil
+}
+
+// curve25519Zeros is just an array of 32 zero bytes so that we have something
+// convenient to compare against in order to reject curve25519 points with the
+// wrong order.
+var curve25519Zeros [32]byte
+
+func (kex *curve25519sha256) Client(c packetConn, rand io.Reader, magics *handshakeMagics) (*kexResult, error) {
+	var kp curve25519KeyPair
+	if err := kp.generate(rand); err != nil {
+		return nil, err
+	}
+	if err := c.writePacket(Marshal(&kexECDHInitMsg{kp.pub[:]})); err != nil {
+		return nil, err
+	}
+
+	packet, err := c.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	var reply kexECDHReplyMsg
+	if err = Unmarshal(packet, &reply); err != nil {
+		return nil, err
+	}
+	if len(reply.EphemeralPubKey) != 32 {
+		return nil, errors.New("ssh: peer's curve25519 public value has wrong length")
+	}
+
+	var servPub, secret [32]byte
+	copy(servPub[:], reply.EphemeralPubKey)
+	curve25519.ScalarMult(&secret, &kp.priv, &servPub)
+	if subtle.ConstantTimeCompare(secret[:], curve25519Zeros[:]) == 1 {
+		return nil, errors.New("ssh: peer's curve25519 public value has wrong order")
+	}
+
+	h := crypto.SHA256.New()
+	magics.write(h)
+	writeString(h, reply.HostKey)
+	writeString(h, kp.pub[:])
+	writeString(h, reply.EphemeralPubKey)
+
+	ki := new(big.Int).SetBytes(secret[:])
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
+	h.Write(K)
+
+	return &kexResult{
+		H:         h.Sum(nil),
+		K:         K,
+		HostKey:   reply.HostKey,
+		Signature: reply.Signature,
+		Hash:      crypto.SHA256,
+	}, nil
+}
+
+func (kex *curve25519sha256) Server(c packetConn, rand io.Reader, magics *handshakeMagics, priv AlgorithmSigner, algo string) (result *kexResult, err error) {
+	packet, err := c.readPacket()
+	if err != nil {
+		return
+	}
+	var kexInit kexECDHInitMsg
+	if err = Unmarshal(packet, &kexInit); err != nil {
+		return
+	}
+
+	if len(kexInit.ClientPubKey) != 32 {
+		return nil, errors.New("ssh: peer's curve25519 public value has wrong length")
+	}
+
+	var kp curve25519KeyPair
+	if err := kp.generate(rand); err != nil {
+		return nil, err
+	}
+
+	var clientPub, secret [32]byte
+	copy(clientPub[:], kexInit.ClientPubKey)
+	curve25519.ScalarMult(&secret, &kp.priv, &clientPub)
+	if subtle.ConstantTimeCompare(secret[:], curve25519Zeros[:]) == 1 {
+		return nil, errors.New("ssh: peer's curve25519 public value has wrong order")
+	}
+
+	hostKeyBytes := priv.PublicKey().Marshal()
+
+	h := crypto.SHA256.New()
+	magics.write(h)
+	writeString(h, hostKeyBytes)
+	writeString(h, kexInit.ClientPubKey)
+	writeString(h, kp.pub[:])
+
+	ki := new(big.Int).SetBytes(secret[:])
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
+	h.Write(K)
+
+	H := h.Sum(nil)
+
+	sig, err := signAndMarshal(priv, rand, H, algo)
+	if err != nil {
+		return nil, err
+	}
+
+	reply := kexECDHReplyMsg{
+		EphemeralPubKey: kp.pub[:],
+		HostKey:         hostKeyBytes,
+		Signature:       sig,
+	}
+	if err := c.writePacket(Marshal(&reply)); err != nil {
+		return nil, err
+	}
+	return &kexResult{
+		H:         H,
+		K:         K,
+		HostKey:   hostKeyBytes,
+		Signature: sig,
+		Hash:      crypto.SHA256,
+	}, nil
+}
+
+// dhGEXSHA implements the diffie-hellman-group-exchange-sha1 and
+// diffie-hellman-group-exchange-sha256 key agreement protocols,
+// as described in RFC 4419
+type dhGEXSHA struct {
+	hashFunc crypto.Hash
+}
+
+const (
+	dhGroupExchangeMinimumBits   = 2048
+	dhGroupExchangePreferredBits = 2048
+	dhGroupExchangeMaximumBits   = 8192
+)
+
+func (gex *dhGEXSHA) Client(c packetConn, randSource io.Reader, magics *handshakeMagics) (*kexResult, error) {
+	// Send GexRequest
+	kexDHGexRequest := kexDHGexRequestMsg{
+		MinBits:      dhGroupExchangeMinimumBits,
+		PreferedBits: dhGroupExchangePreferredBits,
+		MaxBits:      dhGroupExchangeMaximumBits,
+	}
+	if err := c.writePacket(Marshal(&kexDHGexRequest)); err != nil {
+		return nil, err
+	}
+
+	// Receive GexGroup
+	packet, err := c.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	var msg kexDHGexGroupMsg
+	if err = Unmarshal(packet, &msg); err != nil {
+		return nil, err
+	}
+
+	// reject if p's bit length < dhGroupExchangeMinimumBits or > dhGroupExchangeMaximumBits
+	if msg.P.BitLen() < dhGroupExchangeMinimumBits || msg.P.BitLen() > dhGroupExchangeMaximumBits {
+		return nil, fmt.Errorf("ssh: server-generated gex p is out of range (%d bits)", msg.P.BitLen())
+	}
+
+	// Check if g is safe by verifying that 1 < g < p-1
+	pMinusOne := new(big.Int).Sub(msg.P, bigOne)
+	if msg.G.Cmp(bigOne) <= 0 || msg.G.Cmp(pMinusOne) >= 0 {
+		return nil, fmt.Errorf("ssh: server provided gex g is not safe")
+	}
+
+	// Send GexInit
+	pHalf := new(big.Int).Rsh(msg.P, 1)
+	x, err := rand.Int(randSource, pHalf)
+	if err != nil {
+		return nil, err
+	}
+	X := new(big.Int).Exp(msg.G, x, msg.P)
+	kexDHGexInit := kexDHGexInitMsg{
+		X: X,
+	}
+	if err := c.writePacket(Marshal(&kexDHGexInit)); err != nil {
+		return nil, err
+	}
+
+	// Receive GexReply
+	packet, err = c.readPacket()
+	if err != nil {
+		return nil, err
+	}
+
+	var kexDHGexReply kexDHGexReplyMsg
+	if err = Unmarshal(packet, &kexDHGexReply); err != nil {
+		return nil, err
+	}
+
+	if kexDHGexReply.Y.Cmp(bigOne) <= 0 || kexDHGexReply.Y.Cmp(pMinusOne) >= 0 {
+		return nil, errors.New("ssh: DH parameter out of bounds")
+	}
+	kInt := new(big.Int).Exp(kexDHGexReply.Y, x, msg.P)
+
+	// Check if k is safe by verifying that k > 1 and k < p - 1
+	if kInt.Cmp(bigOne) <= 0 || kInt.Cmp(pMinusOne) >= 0 {
+		return nil, fmt.Errorf("ssh: derived k is not safe")
+	}
+
+	h := gex.hashFunc.New()
+	magics.write(h)
+	writeString(h, kexDHGexReply.HostKey)
+	binary.Write(h, binary.BigEndian, uint32(dhGroupExchangeMinimumBits))
+	binary.Write(h, binary.BigEndian, uint32(dhGroupExchangePreferredBits))
+	binary.Write(h, binary.BigEndian, uint32(dhGroupExchangeMaximumBits))
+	writeInt(h, msg.P)
+	writeInt(h, msg.G)
+	writeInt(h, X)
+	writeInt(h, kexDHGexReply.Y)
+	K := make([]byte, intLength(kInt))
+	marshalInt(K, kInt)
+	h.Write(K)
+
+	return &kexResult{
+		H:         h.Sum(nil),
+		K:         K,
+		HostKey:   kexDHGexReply.HostKey,
+		Signature: kexDHGexReply.Signature,
+		Hash:      gex.hashFunc,
+	}, nil
+}
+
+// Server half implementation of the Diffie Hellman Key Exchange with SHA1 and SHA256.
+//
+// This is a minimal implementation to satisfy the automated tests.
+func (gex dhGEXSHA) Server(c packetConn, randSource io.Reader, magics *handshakeMagics, priv AlgorithmSigner, algo string) (result *kexResult, err error) {
+	// Receive GexRequest
+	packet, err := c.readPacket()
+	if err != nil {
+		return
+	}
+	var kexDHGexRequest kexDHGexRequestMsg
+	if err = Unmarshal(packet, &kexDHGexRequest); err != nil {
+		return
+	}
+
+	// Send GexGroup
+	// This is the group called diffie-hellman-group14-sha1 in RFC
+	// 4253 and Oakley Group 14 in RFC 3526.
+	p, _ := new(big.Int).SetString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
+	g := big.NewInt(2)
+
+	msg := &kexDHGexGroupMsg{
+		P: p,
+		G: g,
+	}
+	if err := c.writePacket(Marshal(msg)); err != nil {
+		return nil, err
+	}
+
+	// Receive GexInit
+	packet, err = c.readPacket()
+	if err != nil {
+		return
+	}
+	var kexDHGexInit kexDHGexInitMsg
+	if err = Unmarshal(packet, &kexDHGexInit); err != nil {
+		return
+	}
+
+	pHalf := new(big.Int).Rsh(p, 1)
+
+	y, err := rand.Int(randSource, pHalf)
+	if err != nil {
+		return
+	}
+	Y := new(big.Int).Exp(g, y, p)
+
+	pMinusOne := new(big.Int).Sub(p, bigOne)
+	if kexDHGexInit.X.Cmp(bigOne) <= 0 || kexDHGexInit.X.Cmp(pMinusOne) >= 0 {
+		return nil, errors.New("ssh: DH parameter out of bounds")
+	}
+	kInt := new(big.Int).Exp(kexDHGexInit.X, y, p)
+
+	hostKeyBytes := priv.PublicKey().Marshal()
+
+	h := gex.hashFunc.New()
+	magics.write(h)
+	writeString(h, hostKeyBytes)
+	binary.Write(h, binary.BigEndian, uint32(dhGroupExchangeMinimumBits))
+	binary.Write(h, binary.BigEndian, uint32(dhGroupExchangePreferredBits))
+	binary.Write(h, binary.BigEndian, uint32(dhGroupExchangeMaximumBits))
+	writeInt(h, p)
+	writeInt(h, g)
+	writeInt(h, kexDHGexInit.X)
+	writeInt(h, Y)
+
+	K := make([]byte, intLength(kInt))
+	marshalInt(K, kInt)
+	h.Write(K)
+
+	H := h.Sum(nil)
+
+	// H is already a hash, but the hostkey signing will apply its
+	// own key-specific hash algorithm.
+	sig, err := signAndMarshal(priv, randSource, H, algo)
+	if err != nil {
+		return nil, err
+	}
+
+	kexDHGexReply := kexDHGexReplyMsg{
+		HostKey:   hostKeyBytes,
+		Y:         Y,
+		Signature: sig,
+	}
+	packet = Marshal(&kexDHGexReply)
+
+	err = c.writePacket(packet)
+
+	return &kexResult{
+		H:         H,
+		K:         K,
+		HostKey:   hostKeyBytes,
+		Signature: sig,
+		Hash:      gex.hashFunc,
+	}, err
+}
diff --git a/vendor/golang.org/x/crypto/ssh/keys.go b/vendor/golang.org/x/crypto/ssh/keys.go
new file mode 100644
index 000000000..df4ebdada
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/keys.go
@@ -0,0 +1,1728 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/dsa"
+	"crypto/ecdsa"
+	"crypto/ed25519"
+	"crypto/elliptic"
+	"crypto/md5"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/x509"
+	"encoding/asn1"
+	"encoding/base64"
+	"encoding/binary"
+	"encoding/hex"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io"
+	"math/big"
+	"strings"
+
+	"golang.org/x/crypto/ssh/internal/bcrypt_pbkdf"
+)
+
+// Public key algorithms names. These values can appear in PublicKey.Type,
+// ClientConfig.HostKeyAlgorithms, Signature.Format, or as AlgorithmSigner
+// arguments.
+const (
+	KeyAlgoRSA        = "ssh-rsa"
+	KeyAlgoDSA        = "ssh-dss"
+	KeyAlgoECDSA256   = "ecdsa-sha2-nistp256"
+	KeyAlgoSKECDSA256 = "sk-ecdsa-sha2-nistp256@openssh.com"
+	KeyAlgoECDSA384   = "ecdsa-sha2-nistp384"
+	KeyAlgoECDSA521   = "ecdsa-sha2-nistp521"
+	KeyAlgoED25519    = "ssh-ed25519"
+	KeyAlgoSKED25519  = "sk-ssh-ed25519@openssh.com"
+
+	// KeyAlgoRSASHA256 and KeyAlgoRSASHA512 are only public key algorithms, not
+	// public key formats, so they can't appear as a PublicKey.Type. The
+	// corresponding PublicKey.Type is KeyAlgoRSA. See RFC 8332, Section 2.
+	KeyAlgoRSASHA256 = "rsa-sha2-256"
+	KeyAlgoRSASHA512 = "rsa-sha2-512"
+)
+
+const (
+	// Deprecated: use KeyAlgoRSA.
+	SigAlgoRSA = KeyAlgoRSA
+	// Deprecated: use KeyAlgoRSASHA256.
+	SigAlgoRSASHA2256 = KeyAlgoRSASHA256
+	// Deprecated: use KeyAlgoRSASHA512.
+	SigAlgoRSASHA2512 = KeyAlgoRSASHA512
+)
+
+// parsePubKey parses a public key of the given algorithm.
+// Use ParsePublicKey for keys with prepended algorithm.
+func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err error) {
+	switch algo {
+	case KeyAlgoRSA:
+		return parseRSA(in)
+	case KeyAlgoDSA:
+		return parseDSA(in)
+	case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
+		return parseECDSA(in)
+	case KeyAlgoSKECDSA256:
+		return parseSKECDSA(in)
+	case KeyAlgoED25519:
+		return parseED25519(in)
+	case KeyAlgoSKED25519:
+		return parseSKEd25519(in)
+	case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoSKECDSA256v01, CertAlgoED25519v01, CertAlgoSKED25519v01:
+		cert, err := parseCert(in, certKeyAlgoNames[algo])
+		if err != nil {
+			return nil, nil, err
+		}
+		return cert, nil, nil
+	}
+	return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", algo)
+}
+
+// parseAuthorizedKey parses a public key in OpenSSH authorized_keys format
+// (see sshd(8) manual page) once the options and key type fields have been
+// removed.
+func parseAuthorizedKey(in []byte) (out PublicKey, comment string, err error) {
+	in = bytes.TrimSpace(in)
+
+	i := bytes.IndexAny(in, " \t")
+	if i == -1 {
+		i = len(in)
+	}
+	base64Key := in[:i]
+
+	key := make([]byte, base64.StdEncoding.DecodedLen(len(base64Key)))
+	n, err := base64.StdEncoding.Decode(key, base64Key)
+	if err != nil {
+		return nil, "", err
+	}
+	key = key[:n]
+	out, err = ParsePublicKey(key)
+	if err != nil {
+		return nil, "", err
+	}
+	comment = string(bytes.TrimSpace(in[i:]))
+	return out, comment, nil
+}
+
+// ParseKnownHosts parses an entry in the format of the known_hosts file.
+//
+// The known_hosts format is documented in the sshd(8) manual page. This
+// function will parse a single entry from in. On successful return, marker
+// will contain the optional marker value (i.e. "cert-authority" or "revoked")
+// or else be empty, hosts will contain the hosts that this entry matches,
+// pubKey will contain the public key and comment will contain any trailing
+// comment at the end of the line. See the sshd(8) manual page for the various
+// forms that a host string can take.
+//
+// The unparsed remainder of the input will be returned in rest. This function
+// can be called repeatedly to parse multiple entries.
+//
+// If no entries were found in the input then err will be io.EOF. Otherwise a
+// non-nil err value indicates a parse error.
+func ParseKnownHosts(in []byte) (marker string, hosts []string, pubKey PublicKey, comment string, rest []byte, err error) {
+	for len(in) > 0 {
+		end := bytes.IndexByte(in, '\n')
+		if end != -1 {
+			rest = in[end+1:]
+			in = in[:end]
+		} else {
+			rest = nil
+		}
+
+		end = bytes.IndexByte(in, '\r')
+		if end != -1 {
+			in = in[:end]
+		}
+
+		in = bytes.TrimSpace(in)
+		if len(in) == 0 || in[0] == '#' {
+			in = rest
+			continue
+		}
+
+		i := bytes.IndexAny(in, " \t")
+		if i == -1 {
+			in = rest
+			continue
+		}
+
+		// Strip out the beginning of the known_host key.
+		// This is either an optional marker or a (set of) hostname(s).
+		keyFields := bytes.Fields(in)
+		if len(keyFields) < 3 || len(keyFields) > 5 {
+			return "", nil, nil, "", nil, errors.New("ssh: invalid entry in known_hosts data")
+		}
+
+		// keyFields[0] is either "@cert-authority", "@revoked" or a comma separated
+		// list of hosts
+		marker := ""
+		if keyFields[0][0] == '@' {
+			marker = string(keyFields[0][1:])
+			keyFields = keyFields[1:]
+		}
+
+		hosts := string(keyFields[0])
+		// keyFields[1] contains the key type (e.g. “ssh-rsa”).
+		// However, that information is duplicated inside the
+		// base64-encoded key and so is ignored here.
+
+		key := bytes.Join(keyFields[2:], []byte(" "))
+		if pubKey, comment, err = parseAuthorizedKey(key); err != nil {
+			return "", nil, nil, "", nil, err
+		}
+
+		return marker, strings.Split(hosts, ","), pubKey, comment, rest, nil
+	}
+
+	return "", nil, nil, "", nil, io.EOF
+}
+
+// ParseAuthorizedKey parses a public key from an authorized_keys
+// file used in OpenSSH according to the sshd(8) manual page.
+func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
+	for len(in) > 0 {
+		end := bytes.IndexByte(in, '\n')
+		if end != -1 {
+			rest = in[end+1:]
+			in = in[:end]
+		} else {
+			rest = nil
+		}
+
+		end = bytes.IndexByte(in, '\r')
+		if end != -1 {
+			in = in[:end]
+		}
+
+		in = bytes.TrimSpace(in)
+		if len(in) == 0 || in[0] == '#' {
+			in = rest
+			continue
+		}
+
+		i := bytes.IndexAny(in, " \t")
+		if i == -1 {
+			in = rest
+			continue
+		}
+
+		if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
+			return out, comment, options, rest, nil
+		}
+
+		// No key type recognised. Maybe there's an options field at
+		// the beginning.
+		var b byte
+		inQuote := false
+		var candidateOptions []string
+		optionStart := 0
+		for i, b = range in {
+			isEnd := !inQuote && (b == ' ' || b == '\t')
+			if (b == ',' && !inQuote) || isEnd {
+				if i-optionStart > 0 {
+					candidateOptions = append(candidateOptions, string(in[optionStart:i]))
+				}
+				optionStart = i + 1
+			}
+			if isEnd {
+				break
+			}
+			if b == '"' && (i == 0 || (i > 0 && in[i-1] != '\\')) {
+				inQuote = !inQuote
+			}
+		}
+		for i < len(in) && (in[i] == ' ' || in[i] == '\t') {
+			i++
+		}
+		if i == len(in) {
+			// Invalid line: unmatched quote
+			in = rest
+			continue
+		}
+
+		in = in[i:]
+		i = bytes.IndexAny(in, " \t")
+		if i == -1 {
+			in = rest
+			continue
+		}
+
+		if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
+			options = candidateOptions
+			return out, comment, options, rest, nil
+		}
+
+		in = rest
+		continue
+	}
+
+	return nil, "", nil, nil, errors.New("ssh: no key found")
+}
+
+// ParsePublicKey parses an SSH public key formatted for use in
+// the SSH wire protocol according to RFC 4253, section 6.6.
+func ParsePublicKey(in []byte) (out PublicKey, err error) {
+	algo, in, ok := parseString(in)
+	if !ok {
+		return nil, errShortRead
+	}
+	var rest []byte
+	out, rest, err = parsePubKey(in, string(algo))
+	if len(rest) > 0 {
+		return nil, errors.New("ssh: trailing junk in public key")
+	}
+
+	return out, err
+}
+
+// MarshalAuthorizedKey serializes key for inclusion in an OpenSSH
+// authorized_keys file. The return value ends with newline.
+func MarshalAuthorizedKey(key PublicKey) []byte {
+	b := &bytes.Buffer{}
+	b.WriteString(key.Type())
+	b.WriteByte(' ')
+	e := base64.NewEncoder(base64.StdEncoding, b)
+	e.Write(key.Marshal())
+	e.Close()
+	b.WriteByte('\n')
+	return b.Bytes()
+}
+
+// MarshalPrivateKey returns a PEM block with the private key serialized in the
+// OpenSSH format.
+func MarshalPrivateKey(key crypto.PrivateKey, comment string) (*pem.Block, error) {
+	return marshalOpenSSHPrivateKey(key, comment, unencryptedOpenSSHMarshaler)
+}
+
+// MarshalPrivateKeyWithPassphrase returns a PEM block holding the encrypted
+// private key serialized in the OpenSSH format.
+func MarshalPrivateKeyWithPassphrase(key crypto.PrivateKey, comment string, passphrase []byte) (*pem.Block, error) {
+	return marshalOpenSSHPrivateKey(key, comment, passphraseProtectedOpenSSHMarshaler(passphrase))
+}
+
+// PublicKey represents a public key using an unspecified algorithm.
+//
+// Some PublicKeys provided by this package also implement CryptoPublicKey.
+type PublicKey interface {
+	// Type returns the key format name, e.g. "ssh-rsa".
+	Type() string
+
+	// Marshal returns the serialized key data in SSH wire format, with the name
+	// prefix. To unmarshal the returned data, use the ParsePublicKey function.
+	Marshal() []byte
+
+	// Verify that sig is a signature on the given data using this key. This
+	// method will hash the data appropriately first. sig.Format is allowed to
+	// be any signature algorithm compatible with the key type, the caller
+	// should check if it has more stringent requirements.
+	Verify(data []byte, sig *Signature) error
+}
+
+// CryptoPublicKey, if implemented by a PublicKey,
+// returns the underlying crypto.PublicKey form of the key.
+type CryptoPublicKey interface {
+	CryptoPublicKey() crypto.PublicKey
+}
+
+// A Signer can create signatures that verify against a public key.
+//
+// Some Signers provided by this package also implement MultiAlgorithmSigner.
+type Signer interface {
+	// PublicKey returns the associated PublicKey.
+	PublicKey() PublicKey
+
+	// Sign returns a signature for the given data. This method will hash the
+	// data appropriately first. The signature algorithm is expected to match
+	// the key format returned by the PublicKey.Type method (and not to be any
+	// alternative algorithm supported by the key format).
+	Sign(rand io.Reader, data []byte) (*Signature, error)
+}
+
+// An AlgorithmSigner is a Signer that also supports specifying an algorithm to
+// use for signing.
+//
+// An AlgorithmSigner can't advertise the algorithms it supports, unless it also
+// implements MultiAlgorithmSigner, so it should be prepared to be invoked with
+// every algorithm supported by the public key format.
+type AlgorithmSigner interface {
+	Signer
+
+	// SignWithAlgorithm is like Signer.Sign, but allows specifying a desired
+	// signing algorithm. Callers may pass an empty string for the algorithm in
+	// which case the AlgorithmSigner will use a default algorithm. This default
+	// doesn't currently control any behavior in this package.
+	SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error)
+}
+
+// MultiAlgorithmSigner is an AlgorithmSigner that also reports the algorithms
+// supported by that signer.
+type MultiAlgorithmSigner interface {
+	AlgorithmSigner
+
+	// Algorithms returns the available algorithms in preference order. The list
+	// must not be empty, and it must not include certificate types.
+	Algorithms() []string
+}
+
+// NewSignerWithAlgorithms returns a signer restricted to the specified
+// algorithms. The algorithms must be set in preference order. The list must not
+// be empty, and it must not include certificate types. An error is returned if
+// the specified algorithms are incompatible with the public key type.
+func NewSignerWithAlgorithms(signer AlgorithmSigner, algorithms []string) (MultiAlgorithmSigner, error) {
+	if len(algorithms) == 0 {
+		return nil, errors.New("ssh: please specify at least one valid signing algorithm")
+	}
+	var signerAlgos []string
+	supportedAlgos := algorithmsForKeyFormat(underlyingAlgo(signer.PublicKey().Type()))
+	if s, ok := signer.(*multiAlgorithmSigner); ok {
+		signerAlgos = s.Algorithms()
+	} else {
+		signerAlgos = supportedAlgos
+	}
+
+	for _, algo := range algorithms {
+		if !contains(supportedAlgos, algo) {
+			return nil, fmt.Errorf("ssh: algorithm %q is not supported for key type %q",
+				algo, signer.PublicKey().Type())
+		}
+		if !contains(signerAlgos, algo) {
+			return nil, fmt.Errorf("ssh: algorithm %q is restricted for the provided signer", algo)
+		}
+	}
+	return &multiAlgorithmSigner{
+		AlgorithmSigner:     signer,
+		supportedAlgorithms: algorithms,
+	}, nil
+}
+
+type multiAlgorithmSigner struct {
+	AlgorithmSigner
+	supportedAlgorithms []string
+}
+
+func (s *multiAlgorithmSigner) Algorithms() []string {
+	return s.supportedAlgorithms
+}
+
+func (s *multiAlgorithmSigner) isAlgorithmSupported(algorithm string) bool {
+	if algorithm == "" {
+		algorithm = underlyingAlgo(s.PublicKey().Type())
+	}
+	for _, algo := range s.supportedAlgorithms {
+		if algorithm == algo {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *multiAlgorithmSigner) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
+	if !s.isAlgorithmSupported(algorithm) {
+		return nil, fmt.Errorf("ssh: algorithm %q is not supported: %v", algorithm, s.supportedAlgorithms)
+	}
+	return s.AlgorithmSigner.SignWithAlgorithm(rand, data, algorithm)
+}
+
+type rsaPublicKey rsa.PublicKey
+
+func (r *rsaPublicKey) Type() string {
+	return "ssh-rsa"
+}
+
+// parseRSA parses an RSA key according to RFC 4253, section 6.6.
+func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		E    *big.Int
+		N    *big.Int
+		Rest []byte `ssh:"rest"`
+	}
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	if w.E.BitLen() > 24 {
+		return nil, nil, errors.New("ssh: exponent too large")
+	}
+	e := w.E.Int64()
+	if e < 3 || e&1 == 0 {
+		return nil, nil, errors.New("ssh: incorrect exponent")
+	}
+
+	var key rsa.PublicKey
+	key.E = int(e)
+	key.N = w.N
+	return (*rsaPublicKey)(&key), w.Rest, nil
+}
+
+func (r *rsaPublicKey) Marshal() []byte {
+	e := new(big.Int).SetInt64(int64(r.E))
+	// RSA publickey struct layout should match the struct used by
+	// parseRSACert in the x/crypto/ssh/agent package.
+	wirekey := struct {
+		Name string
+		E    *big.Int
+		N    *big.Int
+	}{
+		KeyAlgoRSA,
+		e,
+		r.N,
+	}
+	return Marshal(&wirekey)
+}
+
+func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
+	supportedAlgos := algorithmsForKeyFormat(r.Type())
+	if !contains(supportedAlgos, sig.Format) {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, r.Type())
+	}
+	hash := hashFuncs[sig.Format]
+	h := hash.New()
+	h.Write(data)
+	digest := h.Sum(nil)
+	return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), hash, digest, sig.Blob)
+}
+
+func (r *rsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*rsa.PublicKey)(r)
+}
+
+type dsaPublicKey dsa.PublicKey
+
+func (k *dsaPublicKey) Type() string {
+	return "ssh-dss"
+}
+
+func checkDSAParams(param *dsa.Parameters) error {
+	// SSH specifies FIPS 186-2, which only provided a single size
+	// (1024 bits) DSA key. FIPS 186-3 allows for larger key
+	// sizes, which would confuse SSH.
+	if l := param.P.BitLen(); l != 1024 {
+		return fmt.Errorf("ssh: unsupported DSA key size %d", l)
+	}
+
+	return nil
+}
+
+// parseDSA parses an DSA key according to RFC 4253, section 6.6.
+func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		P, Q, G, Y *big.Int
+		Rest       []byte `ssh:"rest"`
+	}
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	param := dsa.Parameters{
+		P: w.P,
+		Q: w.Q,
+		G: w.G,
+	}
+	if err := checkDSAParams(&param); err != nil {
+		return nil, nil, err
+	}
+
+	key := &dsaPublicKey{
+		Parameters: param,
+		Y:          w.Y,
+	}
+	return key, w.Rest, nil
+}
+
+func (k *dsaPublicKey) Marshal() []byte {
+	// DSA publickey struct layout should match the struct used by
+	// parseDSACert in the x/crypto/ssh/agent package.
+	w := struct {
+		Name       string
+		P, Q, G, Y *big.Int
+	}{
+		k.Type(),
+		k.P,
+		k.Q,
+		k.G,
+		k.Y,
+	}
+
+	return Marshal(&w)
+}
+
+func (k *dsaPublicKey) Verify(data []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
+	}
+	h := hashFuncs[sig.Format].New()
+	h.Write(data)
+	digest := h.Sum(nil)
+
+	// Per RFC 4253, section 6.6,
+	// The value for 'dss_signature_blob' is encoded as a string containing
+	// r, followed by s (which are 160-bit integers, without lengths or
+	// padding, unsigned, and in network byte order).
+	// For DSS purposes, sig.Blob should be exactly 40 bytes in length.
+	if len(sig.Blob) != 40 {
+		return errors.New("ssh: DSA signature parse error")
+	}
+	r := new(big.Int).SetBytes(sig.Blob[:20])
+	s := new(big.Int).SetBytes(sig.Blob[20:])
+	if dsa.Verify((*dsa.PublicKey)(k), digest, r, s) {
+		return nil
+	}
+	return errors.New("ssh: signature did not verify")
+}
+
+func (k *dsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*dsa.PublicKey)(k)
+}
+
+type dsaPrivateKey struct {
+	*dsa.PrivateKey
+}
+
+func (k *dsaPrivateKey) PublicKey() PublicKey {
+	return (*dsaPublicKey)(&k.PrivateKey.PublicKey)
+}
+
+func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
+	return k.SignWithAlgorithm(rand, data, k.PublicKey().Type())
+}
+
+func (k *dsaPrivateKey) Algorithms() []string {
+	return []string{k.PublicKey().Type()}
+}
+
+func (k *dsaPrivateKey) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
+	if algorithm != "" && algorithm != k.PublicKey().Type() {
+		return nil, fmt.Errorf("ssh: unsupported signature algorithm %s", algorithm)
+	}
+
+	h := hashFuncs[k.PublicKey().Type()].New()
+	h.Write(data)
+	digest := h.Sum(nil)
+	r, s, err := dsa.Sign(rand, k.PrivateKey, digest)
+	if err != nil {
+		return nil, err
+	}
+
+	sig := make([]byte, 40)
+	rb := r.Bytes()
+	sb := s.Bytes()
+
+	copy(sig[20-len(rb):20], rb)
+	copy(sig[40-len(sb):], sb)
+
+	return &Signature{
+		Format: k.PublicKey().Type(),
+		Blob:   sig,
+	}, nil
+}
+
+type ecdsaPublicKey ecdsa.PublicKey
+
+func (k *ecdsaPublicKey) Type() string {
+	return "ecdsa-sha2-" + k.nistID()
+}
+
+func (k *ecdsaPublicKey) nistID() string {
+	switch k.Params().BitSize {
+	case 256:
+		return "nistp256"
+	case 384:
+		return "nistp384"
+	case 521:
+		return "nistp521"
+	}
+	panic("ssh: unsupported ecdsa key size")
+}
+
+type ed25519PublicKey ed25519.PublicKey
+
+func (k ed25519PublicKey) Type() string {
+	return KeyAlgoED25519
+}
+
+func parseED25519(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		KeyBytes []byte
+		Rest     []byte `ssh:"rest"`
+	}
+
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	if l := len(w.KeyBytes); l != ed25519.PublicKeySize {
+		return nil, nil, fmt.Errorf("invalid size %d for Ed25519 public key", l)
+	}
+
+	return ed25519PublicKey(w.KeyBytes), w.Rest, nil
+}
+
+func (k ed25519PublicKey) Marshal() []byte {
+	w := struct {
+		Name     string
+		KeyBytes []byte
+	}{
+		KeyAlgoED25519,
+		[]byte(k),
+	}
+	return Marshal(&w)
+}
+
+func (k ed25519PublicKey) Verify(b []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
+	}
+	if l := len(k); l != ed25519.PublicKeySize {
+		return fmt.Errorf("ssh: invalid size %d for Ed25519 public key", l)
+	}
+
+	if ok := ed25519.Verify(ed25519.PublicKey(k), b, sig.Blob); !ok {
+		return errors.New("ssh: signature did not verify")
+	}
+
+	return nil
+}
+
+func (k ed25519PublicKey) CryptoPublicKey() crypto.PublicKey {
+	return ed25519.PublicKey(k)
+}
+
+func supportedEllipticCurve(curve elliptic.Curve) bool {
+	return curve == elliptic.P256() || curve == elliptic.P384() || curve == elliptic.P521()
+}
+
+// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
+func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		Curve    string
+		KeyBytes []byte
+		Rest     []byte `ssh:"rest"`
+	}
+
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	key := new(ecdsa.PublicKey)
+
+	switch w.Curve {
+	case "nistp256":
+		key.Curve = elliptic.P256()
+	case "nistp384":
+		key.Curve = elliptic.P384()
+	case "nistp521":
+		key.Curve = elliptic.P521()
+	default:
+		return nil, nil, errors.New("ssh: unsupported curve")
+	}
+
+	key.X, key.Y = elliptic.Unmarshal(key.Curve, w.KeyBytes)
+	if key.X == nil || key.Y == nil {
+		return nil, nil, errors.New("ssh: invalid curve point")
+	}
+	return (*ecdsaPublicKey)(key), w.Rest, nil
+}
+
+func (k *ecdsaPublicKey) Marshal() []byte {
+	// See RFC 5656, section 3.1.
+	keyBytes := elliptic.Marshal(k.Curve, k.X, k.Y)
+	// ECDSA publickey struct layout should match the struct used by
+	// parseECDSACert in the x/crypto/ssh/agent package.
+	w := struct {
+		Name string
+		ID   string
+		Key  []byte
+	}{
+		k.Type(),
+		k.nistID(),
+		keyBytes,
+	}
+
+	return Marshal(&w)
+}
+
+func (k *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
+	}
+
+	h := hashFuncs[sig.Format].New()
+	h.Write(data)
+	digest := h.Sum(nil)
+
+	// Per RFC 5656, section 3.1.2,
+	// The ecdsa_signature_blob value has the following specific encoding:
+	//    mpint    r
+	//    mpint    s
+	var ecSig struct {
+		R *big.Int
+		S *big.Int
+	}
+
+	if err := Unmarshal(sig.Blob, &ecSig); err != nil {
+		return err
+	}
+
+	if ecdsa.Verify((*ecdsa.PublicKey)(k), digest, ecSig.R, ecSig.S) {
+		return nil
+	}
+	return errors.New("ssh: signature did not verify")
+}
+
+func (k *ecdsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*ecdsa.PublicKey)(k)
+}
+
+// skFields holds the additional fields present in U2F/FIDO2 signatures.
+// See openssh/PROTOCOL.u2f 'SSH U2F Signatures' for details.
+type skFields struct {
+	// Flags contains U2F/FIDO2 flags such as 'user present'
+	Flags byte
+	// Counter is a monotonic signature counter which can be
+	// used to detect concurrent use of a private key, should
+	// it be extracted from hardware.
+	Counter uint32
+}
+
+type skECDSAPublicKey struct {
+	// application is a URL-like string, typically "ssh:" for SSH.
+	// see openssh/PROTOCOL.u2f for details.
+	application string
+	ecdsa.PublicKey
+}
+
+func (k *skECDSAPublicKey) Type() string {
+	return KeyAlgoSKECDSA256
+}
+
+func (k *skECDSAPublicKey) nistID() string {
+	return "nistp256"
+}
+
+func parseSKECDSA(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		Curve       string
+		KeyBytes    []byte
+		Application string
+		Rest        []byte `ssh:"rest"`
+	}
+
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	key := new(skECDSAPublicKey)
+	key.application = w.Application
+
+	if w.Curve != "nistp256" {
+		return nil, nil, errors.New("ssh: unsupported curve")
+	}
+	key.Curve = elliptic.P256()
+
+	key.X, key.Y = elliptic.Unmarshal(key.Curve, w.KeyBytes)
+	if key.X == nil || key.Y == nil {
+		return nil, nil, errors.New("ssh: invalid curve point")
+	}
+
+	return key, w.Rest, nil
+}
+
+func (k *skECDSAPublicKey) Marshal() []byte {
+	// See RFC 5656, section 3.1.
+	keyBytes := elliptic.Marshal(k.Curve, k.X, k.Y)
+	w := struct {
+		Name        string
+		ID          string
+		Key         []byte
+		Application string
+	}{
+		k.Type(),
+		k.nistID(),
+		keyBytes,
+		k.application,
+	}
+
+	return Marshal(&w)
+}
+
+func (k *skECDSAPublicKey) Verify(data []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
+	}
+
+	h := hashFuncs[sig.Format].New()
+	h.Write([]byte(k.application))
+	appDigest := h.Sum(nil)
+
+	h.Reset()
+	h.Write(data)
+	dataDigest := h.Sum(nil)
+
+	var ecSig struct {
+		R *big.Int
+		S *big.Int
+	}
+	if err := Unmarshal(sig.Blob, &ecSig); err != nil {
+		return err
+	}
+
+	var skf skFields
+	if err := Unmarshal(sig.Rest, &skf); err != nil {
+		return err
+	}
+
+	blob := struct {
+		ApplicationDigest []byte `ssh:"rest"`
+		Flags             byte
+		Counter           uint32
+		MessageDigest     []byte `ssh:"rest"`
+	}{
+		appDigest,
+		skf.Flags,
+		skf.Counter,
+		dataDigest,
+	}
+
+	original := Marshal(blob)
+
+	h.Reset()
+	h.Write(original)
+	digest := h.Sum(nil)
+
+	if ecdsa.Verify((*ecdsa.PublicKey)(&k.PublicKey), digest, ecSig.R, ecSig.S) {
+		return nil
+	}
+	return errors.New("ssh: signature did not verify")
+}
+
+type skEd25519PublicKey struct {
+	// application is a URL-like string, typically "ssh:" for SSH.
+	// see openssh/PROTOCOL.u2f for details.
+	application string
+	ed25519.PublicKey
+}
+
+func (k *skEd25519PublicKey) Type() string {
+	return KeyAlgoSKED25519
+}
+
+func parseSKEd25519(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		KeyBytes    []byte
+		Application string
+		Rest        []byte `ssh:"rest"`
+	}
+
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	if l := len(w.KeyBytes); l != ed25519.PublicKeySize {
+		return nil, nil, fmt.Errorf("invalid size %d for Ed25519 public key", l)
+	}
+
+	key := new(skEd25519PublicKey)
+	key.application = w.Application
+	key.PublicKey = ed25519.PublicKey(w.KeyBytes)
+
+	return key, w.Rest, nil
+}
+
+func (k *skEd25519PublicKey) Marshal() []byte {
+	w := struct {
+		Name        string
+		KeyBytes    []byte
+		Application string
+	}{
+		KeyAlgoSKED25519,
+		[]byte(k.PublicKey),
+		k.application,
+	}
+	return Marshal(&w)
+}
+
+func (k *skEd25519PublicKey) Verify(data []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
+	}
+	if l := len(k.PublicKey); l != ed25519.PublicKeySize {
+		return fmt.Errorf("invalid size %d for Ed25519 public key", l)
+	}
+
+	h := hashFuncs[sig.Format].New()
+	h.Write([]byte(k.application))
+	appDigest := h.Sum(nil)
+
+	h.Reset()
+	h.Write(data)
+	dataDigest := h.Sum(nil)
+
+	var edSig struct {
+		Signature []byte `ssh:"rest"`
+	}
+
+	if err := Unmarshal(sig.Blob, &edSig); err != nil {
+		return err
+	}
+
+	var skf skFields
+	if err := Unmarshal(sig.Rest, &skf); err != nil {
+		return err
+	}
+
+	blob := struct {
+		ApplicationDigest []byte `ssh:"rest"`
+		Flags             byte
+		Counter           uint32
+		MessageDigest     []byte `ssh:"rest"`
+	}{
+		appDigest,
+		skf.Flags,
+		skf.Counter,
+		dataDigest,
+	}
+
+	original := Marshal(blob)
+
+	if ok := ed25519.Verify(k.PublicKey, original, edSig.Signature); !ok {
+		return errors.New("ssh: signature did not verify")
+	}
+
+	return nil
+}
+
+// NewSignerFromKey takes an *rsa.PrivateKey, *dsa.PrivateKey,
+// *ecdsa.PrivateKey or any other crypto.Signer and returns a
+// corresponding Signer instance. ECDSA keys must use P-256, P-384 or
+// P-521. DSA keys must use parameter size L1024N160.
+func NewSignerFromKey(key interface{}) (Signer, error) {
+	switch key := key.(type) {
+	case crypto.Signer:
+		return NewSignerFromSigner(key)
+	case *dsa.PrivateKey:
+		return newDSAPrivateKey(key)
+	default:
+		return nil, fmt.Errorf("ssh: unsupported key type %T", key)
+	}
+}
+
+func newDSAPrivateKey(key *dsa.PrivateKey) (Signer, error) {
+	if err := checkDSAParams(&key.PublicKey.Parameters); err != nil {
+		return nil, err
+	}
+
+	return &dsaPrivateKey{key}, nil
+}
+
+type wrappedSigner struct {
+	signer crypto.Signer
+	pubKey PublicKey
+}
+
+// NewSignerFromSigner takes any crypto.Signer implementation and
+// returns a corresponding Signer interface. This can be used, for
+// example, with keys kept in hardware modules.
+func NewSignerFromSigner(signer crypto.Signer) (Signer, error) {
+	pubKey, err := NewPublicKey(signer.Public())
+	if err != nil {
+		return nil, err
+	}
+
+	return &wrappedSigner{signer, pubKey}, nil
+}
+
+func (s *wrappedSigner) PublicKey() PublicKey {
+	return s.pubKey
+}
+
+func (s *wrappedSigner) Sign(rand io.Reader, data []byte) (*Signature, error) {
+	return s.SignWithAlgorithm(rand, data, s.pubKey.Type())
+}
+
+func (s *wrappedSigner) Algorithms() []string {
+	return algorithmsForKeyFormat(s.pubKey.Type())
+}
+
+func (s *wrappedSigner) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
+	if algorithm == "" {
+		algorithm = s.pubKey.Type()
+	}
+
+	if !contains(s.Algorithms(), algorithm) {
+		return nil, fmt.Errorf("ssh: unsupported signature algorithm %q for key format %q", algorithm, s.pubKey.Type())
+	}
+
+	hashFunc := hashFuncs[algorithm]
+	var digest []byte
+	if hashFunc != 0 {
+		h := hashFunc.New()
+		h.Write(data)
+		digest = h.Sum(nil)
+	} else {
+		digest = data
+	}
+
+	signature, err := s.signer.Sign(rand, digest, hashFunc)
+	if err != nil {
+		return nil, err
+	}
+
+	// crypto.Signer.Sign is expected to return an ASN.1-encoded signature
+	// for ECDSA and DSA, but that's not the encoding expected by SSH, so
+	// re-encode.
+	switch s.pubKey.(type) {
+	case *ecdsaPublicKey, *dsaPublicKey:
+		type asn1Signature struct {
+			R, S *big.Int
+		}
+		asn1Sig := new(asn1Signature)
+		_, err := asn1.Unmarshal(signature, asn1Sig)
+		if err != nil {
+			return nil, err
+		}
+
+		switch s.pubKey.(type) {
+		case *ecdsaPublicKey:
+			signature = Marshal(asn1Sig)
+
+		case *dsaPublicKey:
+			signature = make([]byte, 40)
+			r := asn1Sig.R.Bytes()
+			s := asn1Sig.S.Bytes()
+			copy(signature[20-len(r):20], r)
+			copy(signature[40-len(s):40], s)
+		}
+	}
+
+	return &Signature{
+		Format: algorithm,
+		Blob:   signature,
+	}, nil
+}
+
+// NewPublicKey takes an *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey,
+// or ed25519.PublicKey returns a corresponding PublicKey instance.
+// ECDSA keys must use P-256, P-384 or P-521.
+func NewPublicKey(key interface{}) (PublicKey, error) {
+	switch key := key.(type) {
+	case *rsa.PublicKey:
+		return (*rsaPublicKey)(key), nil
+	case *ecdsa.PublicKey:
+		if !supportedEllipticCurve(key.Curve) {
+			return nil, errors.New("ssh: only P-256, P-384 and P-521 EC keys are supported")
+		}
+		return (*ecdsaPublicKey)(key), nil
+	case *dsa.PublicKey:
+		return (*dsaPublicKey)(key), nil
+	case ed25519.PublicKey:
+		if l := len(key); l != ed25519.PublicKeySize {
+			return nil, fmt.Errorf("ssh: invalid size %d for Ed25519 public key", l)
+		}
+		return ed25519PublicKey(key), nil
+	default:
+		return nil, fmt.Errorf("ssh: unsupported key type %T", key)
+	}
+}
+
+// ParsePrivateKey returns a Signer from a PEM encoded private key. It supports
+// the same keys as ParseRawPrivateKey. If the private key is encrypted, it
+// will return a PassphraseMissingError.
+func ParsePrivateKey(pemBytes []byte) (Signer, error) {
+	key, err := ParseRawPrivateKey(pemBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewSignerFromKey(key)
+}
+
+// ParsePrivateKeyWithPassphrase returns a Signer from a PEM encoded private
+// key and passphrase. It supports the same keys as
+// ParseRawPrivateKeyWithPassphrase.
+func ParsePrivateKeyWithPassphrase(pemBytes, passphrase []byte) (Signer, error) {
+	key, err := ParseRawPrivateKeyWithPassphrase(pemBytes, passphrase)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewSignerFromKey(key)
+}
+
+// encryptedBlock tells whether a private key is
+// encrypted by examining its Proc-Type header
+// for a mention of ENCRYPTED
+// according to RFC 1421 Section 4.6.1.1.
+func encryptedBlock(block *pem.Block) bool {
+	return strings.Contains(block.Headers["Proc-Type"], "ENCRYPTED")
+}
+
+// A PassphraseMissingError indicates that parsing this private key requires a
+// passphrase. Use ParsePrivateKeyWithPassphrase.
+type PassphraseMissingError struct {
+	// PublicKey will be set if the private key format includes an unencrypted
+	// public key along with the encrypted private key.
+	PublicKey PublicKey
+}
+
+func (*PassphraseMissingError) Error() string {
+	return "ssh: this private key is passphrase protected"
+}
+
+// ParseRawPrivateKey returns a private key from a PEM encoded private key. It supports
+// RSA, DSA, ECDSA, and Ed25519 private keys in PKCS#1, PKCS#8, OpenSSL, and OpenSSH
+// formats. If the private key is encrypted, it will return a PassphraseMissingError.
+func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		return nil, errors.New("ssh: no key found")
+	}
+
+	if encryptedBlock(block) {
+		return nil, &PassphraseMissingError{}
+	}
+
+	switch block.Type {
+	case "RSA PRIVATE KEY":
+		return x509.ParsePKCS1PrivateKey(block.Bytes)
+	// RFC5208 - https://tools.ietf.org/html/rfc5208
+	case "PRIVATE KEY":
+		return x509.ParsePKCS8PrivateKey(block.Bytes)
+	case "EC PRIVATE KEY":
+		return x509.ParseECPrivateKey(block.Bytes)
+	case "DSA PRIVATE KEY":
+		return ParseDSAPrivateKey(block.Bytes)
+	case "OPENSSH PRIVATE KEY":
+		return parseOpenSSHPrivateKey(block.Bytes, unencryptedOpenSSHKey)
+	default:
+		return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
+	}
+}
+
+// ParseRawPrivateKeyWithPassphrase returns a private key decrypted with
+// passphrase from a PEM encoded private key. If the passphrase is wrong, it
+// will return x509.IncorrectPasswordError.
+func ParseRawPrivateKeyWithPassphrase(pemBytes, passphrase []byte) (interface{}, error) {
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		return nil, errors.New("ssh: no key found")
+	}
+
+	if block.Type == "OPENSSH PRIVATE KEY" {
+		return parseOpenSSHPrivateKey(block.Bytes, passphraseProtectedOpenSSHKey(passphrase))
+	}
+
+	if !encryptedBlock(block) || !x509.IsEncryptedPEMBlock(block) {
+		return nil, errors.New("ssh: not an encrypted key")
+	}
+
+	buf, err := x509.DecryptPEMBlock(block, passphrase)
+	if err != nil {
+		if err == x509.IncorrectPasswordError {
+			return nil, err
+		}
+		return nil, fmt.Errorf("ssh: cannot decode encrypted private keys: %v", err)
+	}
+
+	var result interface{}
+
+	switch block.Type {
+	case "RSA PRIVATE KEY":
+		result, err = x509.ParsePKCS1PrivateKey(buf)
+	case "EC PRIVATE KEY":
+		result, err = x509.ParseECPrivateKey(buf)
+	case "DSA PRIVATE KEY":
+		result, err = ParseDSAPrivateKey(buf)
+	default:
+		err = fmt.Errorf("ssh: unsupported key type %q", block.Type)
+	}
+	// Because of deficiencies in the format, DecryptPEMBlock does not always
+	// detect an incorrect password. In these cases decrypted DER bytes is
+	// random noise. If the parsing of the key returns an asn1.StructuralError
+	// we return x509.IncorrectPasswordError.
+	if _, ok := err.(asn1.StructuralError); ok {
+		return nil, x509.IncorrectPasswordError
+	}
+
+	return result, err
+}
+
+// ParseDSAPrivateKey returns a DSA private key from its ASN.1 DER encoding, as
+// specified by the OpenSSL DSA man page.
+func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
+	var k struct {
+		Version int
+		P       *big.Int
+		Q       *big.Int
+		G       *big.Int
+		Pub     *big.Int
+		Priv    *big.Int
+	}
+	rest, err := asn1.Unmarshal(der, &k)
+	if err != nil {
+		return nil, errors.New("ssh: failed to parse DSA key: " + err.Error())
+	}
+	if len(rest) > 0 {
+		return nil, errors.New("ssh: garbage after DSA key")
+	}
+
+	return &dsa.PrivateKey{
+		PublicKey: dsa.PublicKey{
+			Parameters: dsa.Parameters{
+				P: k.P,
+				Q: k.Q,
+				G: k.G,
+			},
+			Y: k.Pub,
+		},
+		X: k.Priv,
+	}, nil
+}
+
+func unencryptedOpenSSHKey(cipherName, kdfName, kdfOpts string, privKeyBlock []byte) ([]byte, error) {
+	if kdfName != "none" || cipherName != "none" {
+		return nil, &PassphraseMissingError{}
+	}
+	if kdfOpts != "" {
+		return nil, errors.New("ssh: invalid openssh private key")
+	}
+	return privKeyBlock, nil
+}
+
+func passphraseProtectedOpenSSHKey(passphrase []byte) openSSHDecryptFunc {
+	return func(cipherName, kdfName, kdfOpts string, privKeyBlock []byte) ([]byte, error) {
+		if kdfName == "none" || cipherName == "none" {
+			return nil, errors.New("ssh: key is not password protected")
+		}
+		if kdfName != "bcrypt" {
+			return nil, fmt.Errorf("ssh: unknown KDF %q, only supports %q", kdfName, "bcrypt")
+		}
+
+		var opts struct {
+			Salt   string
+			Rounds uint32
+		}
+		if err := Unmarshal([]byte(kdfOpts), &opts); err != nil {
+			return nil, err
+		}
+
+		k, err := bcrypt_pbkdf.Key(passphrase, []byte(opts.Salt), int(opts.Rounds), 32+16)
+		if err != nil {
+			return nil, err
+		}
+		key, iv := k[:32], k[32:]
+
+		c, err := aes.NewCipher(key)
+		if err != nil {
+			return nil, err
+		}
+		switch cipherName {
+		case "aes256-ctr":
+			ctr := cipher.NewCTR(c, iv)
+			ctr.XORKeyStream(privKeyBlock, privKeyBlock)
+		case "aes256-cbc":
+			if len(privKeyBlock)%c.BlockSize() != 0 {
+				return nil, fmt.Errorf("ssh: invalid encrypted private key length, not a multiple of the block size")
+			}
+			cbc := cipher.NewCBCDecrypter(c, iv)
+			cbc.CryptBlocks(privKeyBlock, privKeyBlock)
+		default:
+			return nil, fmt.Errorf("ssh: unknown cipher %q, only supports %q or %q", cipherName, "aes256-ctr", "aes256-cbc")
+		}
+
+		return privKeyBlock, nil
+	}
+}
+
+func unencryptedOpenSSHMarshaler(privKeyBlock []byte) ([]byte, string, string, string, error) {
+	key := generateOpenSSHPadding(privKeyBlock, 8)
+	return key, "none", "none", "", nil
+}
+
+func passphraseProtectedOpenSSHMarshaler(passphrase []byte) openSSHEncryptFunc {
+	return func(privKeyBlock []byte) ([]byte, string, string, string, error) {
+		salt := make([]byte, 16)
+		if _, err := rand.Read(salt); err != nil {
+			return nil, "", "", "", err
+		}
+
+		opts := struct {
+			Salt   []byte
+			Rounds uint32
+		}{salt, 16}
+
+		// Derive key to encrypt the private key block.
+		k, err := bcrypt_pbkdf.Key(passphrase, salt, int(opts.Rounds), 32+aes.BlockSize)
+		if err != nil {
+			return nil, "", "", "", err
+		}
+
+		// Add padding matching the block size of AES.
+		keyBlock := generateOpenSSHPadding(privKeyBlock, aes.BlockSize)
+
+		// Encrypt the private key using the derived secret.
+
+		dst := make([]byte, len(keyBlock))
+		key, iv := k[:32], k[32:]
+		block, err := aes.NewCipher(key)
+		if err != nil {
+			return nil, "", "", "", err
+		}
+
+		stream := cipher.NewCTR(block, iv)
+		stream.XORKeyStream(dst, keyBlock)
+
+		return dst, "aes256-ctr", "bcrypt", string(Marshal(opts)), nil
+	}
+}
+
+const privateKeyAuthMagic = "openssh-key-v1\x00"
+
+type openSSHDecryptFunc func(CipherName, KdfName, KdfOpts string, PrivKeyBlock []byte) ([]byte, error)
+type openSSHEncryptFunc func(PrivKeyBlock []byte) (ProtectedKeyBlock []byte, cipherName, kdfName, kdfOptions string, err error)
+
+type openSSHEncryptedPrivateKey struct {
+	CipherName   string
+	KdfName      string
+	KdfOpts      string
+	NumKeys      uint32
+	PubKey       []byte
+	PrivKeyBlock []byte
+}
+
+type openSSHPrivateKey struct {
+	Check1  uint32
+	Check2  uint32
+	Keytype string
+	Rest    []byte `ssh:"rest"`
+}
+
+type openSSHRSAPrivateKey struct {
+	N       *big.Int
+	E       *big.Int
+	D       *big.Int
+	Iqmp    *big.Int
+	P       *big.Int
+	Q       *big.Int
+	Comment string
+	Pad     []byte `ssh:"rest"`
+}
+
+type openSSHEd25519PrivateKey struct {
+	Pub     []byte
+	Priv    []byte
+	Comment string
+	Pad     []byte `ssh:"rest"`
+}
+
+type openSSHECDSAPrivateKey struct {
+	Curve   string
+	Pub     []byte
+	D       *big.Int
+	Comment string
+	Pad     []byte `ssh:"rest"`
+}
+
+// parseOpenSSHPrivateKey parses an OpenSSH private key, using the decrypt
+// function to unwrap the encrypted portion. unencryptedOpenSSHKey can be used
+// as the decrypt function to parse an unencrypted private key. See
+// https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key.
+func parseOpenSSHPrivateKey(key []byte, decrypt openSSHDecryptFunc) (crypto.PrivateKey, error) {
+	if len(key) < len(privateKeyAuthMagic) || string(key[:len(privateKeyAuthMagic)]) != privateKeyAuthMagic {
+		return nil, errors.New("ssh: invalid openssh private key format")
+	}
+	remaining := key[len(privateKeyAuthMagic):]
+
+	var w openSSHEncryptedPrivateKey
+	if err := Unmarshal(remaining, &w); err != nil {
+		return nil, err
+	}
+	if w.NumKeys != 1 {
+		// We only support single key files, and so does OpenSSH.
+		// https://github.com/openssh/openssh-portable/blob/4103a3ec7/sshkey.c#L4171
+		return nil, errors.New("ssh: multi-key files are not supported")
+	}
+
+	privKeyBlock, err := decrypt(w.CipherName, w.KdfName, w.KdfOpts, w.PrivKeyBlock)
+	if err != nil {
+		if err, ok := err.(*PassphraseMissingError); ok {
+			pub, errPub := ParsePublicKey(w.PubKey)
+			if errPub != nil {
+				return nil, fmt.Errorf("ssh: failed to parse embedded public key: %v", errPub)
+			}
+			err.PublicKey = pub
+		}
+		return nil, err
+	}
+
+	var pk1 openSSHPrivateKey
+	if err := Unmarshal(privKeyBlock, &pk1); err != nil || pk1.Check1 != pk1.Check2 {
+		if w.CipherName != "none" {
+			return nil, x509.IncorrectPasswordError
+		}
+		return nil, errors.New("ssh: malformed OpenSSH key")
+	}
+
+	switch pk1.Keytype {
+	case KeyAlgoRSA:
+		var key openSSHRSAPrivateKey
+		if err := Unmarshal(pk1.Rest, &key); err != nil {
+			return nil, err
+		}
+
+		if err := checkOpenSSHKeyPadding(key.Pad); err != nil {
+			return nil, err
+		}
+
+		pk := &rsa.PrivateKey{
+			PublicKey: rsa.PublicKey{
+				N: key.N,
+				E: int(key.E.Int64()),
+			},
+			D:      key.D,
+			Primes: []*big.Int{key.P, key.Q},
+		}
+
+		if err := pk.Validate(); err != nil {
+			return nil, err
+		}
+
+		pk.Precompute()
+
+		return pk, nil
+	case KeyAlgoED25519:
+		var key openSSHEd25519PrivateKey
+		if err := Unmarshal(pk1.Rest, &key); err != nil {
+			return nil, err
+		}
+
+		if len(key.Priv) != ed25519.PrivateKeySize {
+			return nil, errors.New("ssh: private key unexpected length")
+		}
+
+		if err := checkOpenSSHKeyPadding(key.Pad); err != nil {
+			return nil, err
+		}
+
+		pk := ed25519.PrivateKey(make([]byte, ed25519.PrivateKeySize))
+		copy(pk, key.Priv)
+		return &pk, nil
+	case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
+		var key openSSHECDSAPrivateKey
+		if err := Unmarshal(pk1.Rest, &key); err != nil {
+			return nil, err
+		}
+
+		if err := checkOpenSSHKeyPadding(key.Pad); err != nil {
+			return nil, err
+		}
+
+		var curve elliptic.Curve
+		switch key.Curve {
+		case "nistp256":
+			curve = elliptic.P256()
+		case "nistp384":
+			curve = elliptic.P384()
+		case "nistp521":
+			curve = elliptic.P521()
+		default:
+			return nil, errors.New("ssh: unhandled elliptic curve: " + key.Curve)
+		}
+
+		X, Y := elliptic.Unmarshal(curve, key.Pub)
+		if X == nil || Y == nil {
+			return nil, errors.New("ssh: failed to unmarshal public key")
+		}
+
+		if key.D.Cmp(curve.Params().N) >= 0 {
+			return nil, errors.New("ssh: scalar is out of range")
+		}
+
+		x, y := curve.ScalarBaseMult(key.D.Bytes())
+		if x.Cmp(X) != 0 || y.Cmp(Y) != 0 {
+			return nil, errors.New("ssh: public key does not match private key")
+		}
+
+		return &ecdsa.PrivateKey{
+			PublicKey: ecdsa.PublicKey{
+				Curve: curve,
+				X:     X,
+				Y:     Y,
+			},
+			D: key.D,
+		}, nil
+	default:
+		return nil, errors.New("ssh: unhandled key type")
+	}
+}
+
+func marshalOpenSSHPrivateKey(key crypto.PrivateKey, comment string, encrypt openSSHEncryptFunc) (*pem.Block, error) {
+	var w openSSHEncryptedPrivateKey
+	var pk1 openSSHPrivateKey
+
+	// Random check bytes.
+	var check uint32
+	if err := binary.Read(rand.Reader, binary.BigEndian, &check); err != nil {
+		return nil, err
+	}
+
+	pk1.Check1 = check
+	pk1.Check2 = check
+	w.NumKeys = 1
+
+	// Use a []byte directly on ed25519 keys.
+	if k, ok := key.(*ed25519.PrivateKey); ok {
+		key = *k
+	}
+
+	switch k := key.(type) {
+	case *rsa.PrivateKey:
+		E := new(big.Int).SetInt64(int64(k.PublicKey.E))
+		// Marshal public key:
+		// E and N are in reversed order in the public and private key.
+		pubKey := struct {
+			KeyType string
+			E       *big.Int
+			N       *big.Int
+		}{
+			KeyAlgoRSA,
+			E, k.PublicKey.N,
+		}
+		w.PubKey = Marshal(pubKey)
+
+		// Marshal private key.
+		key := openSSHRSAPrivateKey{
+			N:       k.PublicKey.N,
+			E:       E,
+			D:       k.D,
+			Iqmp:    k.Precomputed.Qinv,
+			P:       k.Primes[0],
+			Q:       k.Primes[1],
+			Comment: comment,
+		}
+		pk1.Keytype = KeyAlgoRSA
+		pk1.Rest = Marshal(key)
+	case ed25519.PrivateKey:
+		pub := make([]byte, ed25519.PublicKeySize)
+		priv := make([]byte, ed25519.PrivateKeySize)
+		copy(pub, k[32:])
+		copy(priv, k)
+
+		// Marshal public key.
+		pubKey := struct {
+			KeyType string
+			Pub     []byte
+		}{
+			KeyAlgoED25519, pub,
+		}
+		w.PubKey = Marshal(pubKey)
+
+		// Marshal private key.
+		key := openSSHEd25519PrivateKey{
+			Pub:     pub,
+			Priv:    priv,
+			Comment: comment,
+		}
+		pk1.Keytype = KeyAlgoED25519
+		pk1.Rest = Marshal(key)
+	case *ecdsa.PrivateKey:
+		var curve, keyType string
+		switch name := k.Curve.Params().Name; name {
+		case "P-256":
+			curve = "nistp256"
+			keyType = KeyAlgoECDSA256
+		case "P-384":
+			curve = "nistp384"
+			keyType = KeyAlgoECDSA384
+		case "P-521":
+			curve = "nistp521"
+			keyType = KeyAlgoECDSA521
+		default:
+			return nil, errors.New("ssh: unhandled elliptic curve " + name)
+		}
+
+		pub := elliptic.Marshal(k.Curve, k.PublicKey.X, k.PublicKey.Y)
+
+		// Marshal public key.
+		pubKey := struct {
+			KeyType string
+			Curve   string
+			Pub     []byte
+		}{
+			keyType, curve, pub,
+		}
+		w.PubKey = Marshal(pubKey)
+
+		// Marshal private key.
+		key := openSSHECDSAPrivateKey{
+			Curve:   curve,
+			Pub:     pub,
+			D:       k.D,
+			Comment: comment,
+		}
+		pk1.Keytype = keyType
+		pk1.Rest = Marshal(key)
+	default:
+		return nil, fmt.Errorf("ssh: unsupported key type %T", k)
+	}
+
+	var err error
+	// Add padding and encrypt the key if necessary.
+	w.PrivKeyBlock, w.CipherName, w.KdfName, w.KdfOpts, err = encrypt(Marshal(pk1))
+	if err != nil {
+		return nil, err
+	}
+
+	b := Marshal(w)
+	block := &pem.Block{
+		Type:  "OPENSSH PRIVATE KEY",
+		Bytes: append([]byte(privateKeyAuthMagic), b...),
+	}
+	return block, nil
+}
+
+func checkOpenSSHKeyPadding(pad []byte) error {
+	for i, b := range pad {
+		if int(b) != i+1 {
+			return errors.New("ssh: padding not as expected")
+		}
+	}
+	return nil
+}
+
+func generateOpenSSHPadding(block []byte, blockSize int) []byte {
+	for i, l := 0, len(block); (l+i)%blockSize != 0; i++ {
+		block = append(block, byte(i+1))
+	}
+	return block
+}
+
+// FingerprintLegacyMD5 returns the user presentation of the key's
+// fingerprint as described by RFC 4716 section 4.
+func FingerprintLegacyMD5(pubKey PublicKey) string {
+	md5sum := md5.Sum(pubKey.Marshal())
+	hexarray := make([]string, len(md5sum))
+	for i, c := range md5sum {
+		hexarray[i] = hex.EncodeToString([]byte{c})
+	}
+	return strings.Join(hexarray, ":")
+}
+
+// FingerprintSHA256 returns the user presentation of the key's
+// fingerprint as unpadded base64 encoded sha256 hash.
+// This format was introduced from OpenSSH 6.8.
+// https://www.openssh.com/txt/release-6.8
+// https://tools.ietf.org/html/rfc4648#section-3.2 (unpadded base64 encoding)
+func FingerprintSHA256(pubKey PublicKey) string {
+	sha256sum := sha256.Sum256(pubKey.Marshal())
+	hash := base64.RawStdEncoding.EncodeToString(sha256sum[:])
+	return "SHA256:" + hash
+}
diff --git a/vendor/golang.org/x/crypto/ssh/mac.go b/vendor/golang.org/x/crypto/ssh/mac.go
new file mode 100644
index 000000000..06a1b2750
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/mac.go
@@ -0,0 +1,68 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+// Message authentication support
+
+import (
+	"crypto/hmac"
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/sha512"
+	"hash"
+)
+
+type macMode struct {
+	keySize int
+	etm     bool
+	new     func(key []byte) hash.Hash
+}
+
+// truncatingMAC wraps around a hash.Hash and truncates the output digest to
+// a given size.
+type truncatingMAC struct {
+	length int
+	hmac   hash.Hash
+}
+
+func (t truncatingMAC) Write(data []byte) (int, error) {
+	return t.hmac.Write(data)
+}
+
+func (t truncatingMAC) Sum(in []byte) []byte {
+	out := t.hmac.Sum(in)
+	return out[:len(in)+t.length]
+}
+
+func (t truncatingMAC) Reset() {
+	t.hmac.Reset()
+}
+
+func (t truncatingMAC) Size() int {
+	return t.length
+}
+
+func (t truncatingMAC) BlockSize() int { return t.hmac.BlockSize() }
+
+var macModes = map[string]*macMode{
+	"hmac-sha2-512-etm@openssh.com": {64, true, func(key []byte) hash.Hash {
+		return hmac.New(sha512.New, key)
+	}},
+	"hmac-sha2-256-etm@openssh.com": {32, true, func(key []byte) hash.Hash {
+		return hmac.New(sha256.New, key)
+	}},
+	"hmac-sha2-512": {64, false, func(key []byte) hash.Hash {
+		return hmac.New(sha512.New, key)
+	}},
+	"hmac-sha2-256": {32, false, func(key []byte) hash.Hash {
+		return hmac.New(sha256.New, key)
+	}},
+	"hmac-sha1": {20, false, func(key []byte) hash.Hash {
+		return hmac.New(sha1.New, key)
+	}},
+	"hmac-sha1-96": {20, false, func(key []byte) hash.Hash {
+		return truncatingMAC{12, hmac.New(sha1.New, key)}
+	}},
+}
diff --git a/vendor/golang.org/x/crypto/ssh/messages.go b/vendor/golang.org/x/crypto/ssh/messages.go
new file mode 100644
index 000000000..b55f86056
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/messages.go
@@ -0,0 +1,891 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math/big"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// These are SSH message type numbers. They are scattered around several
+// documents but many were taken from [SSH-PARAMETERS].
+const (
+	msgIgnore        = 2
+	msgUnimplemented = 3
+	msgDebug         = 4
+	msgNewKeys       = 21
+)
+
+// SSH messages:
+//
+// These structures mirror the wire format of the corresponding SSH messages.
+// They are marshaled using reflection with the marshal and unmarshal functions
+// in this file. The only wrinkle is that a final member of type []byte with a
+// ssh tag of "rest" receives the remainder of a packet when unmarshaling.
+
+// See RFC 4253, section 11.1.
+const msgDisconnect = 1
+
+// disconnectMsg is the message that signals a disconnect. It is also
+// the error type returned from mux.Wait()
+type disconnectMsg struct {
+	Reason   uint32 `sshtype:"1"`
+	Message  string
+	Language string
+}
+
+func (d *disconnectMsg) Error() string {
+	return fmt.Sprintf("ssh: disconnect, reason %d: %s", d.Reason, d.Message)
+}
+
+// See RFC 4253, section 7.1.
+const msgKexInit = 20
+
+type kexInitMsg struct {
+	Cookie                  [16]byte `sshtype:"20"`
+	KexAlgos                []string
+	ServerHostKeyAlgos      []string
+	CiphersClientServer     []string
+	CiphersServerClient     []string
+	MACsClientServer        []string
+	MACsServerClient        []string
+	CompressionClientServer []string
+	CompressionServerClient []string
+	LanguagesClientServer   []string
+	LanguagesServerClient   []string
+	FirstKexFollows         bool
+	Reserved                uint32
+}
+
+// See RFC 4253, section 8.
+
+// Diffie-Hellman
+const msgKexDHInit = 30
+
+type kexDHInitMsg struct {
+	X *big.Int `sshtype:"30"`
+}
+
+const msgKexECDHInit = 30
+
+type kexECDHInitMsg struct {
+	ClientPubKey []byte `sshtype:"30"`
+}
+
+const msgKexECDHReply = 31
+
+type kexECDHReplyMsg struct {
+	HostKey         []byte `sshtype:"31"`
+	EphemeralPubKey []byte
+	Signature       []byte
+}
+
+const msgKexDHReply = 31
+
+type kexDHReplyMsg struct {
+	HostKey   []byte `sshtype:"31"`
+	Y         *big.Int
+	Signature []byte
+}
+
+// See RFC 4419, section 5.
+const msgKexDHGexGroup = 31
+
+type kexDHGexGroupMsg struct {
+	P *big.Int `sshtype:"31"`
+	G *big.Int
+}
+
+const msgKexDHGexInit = 32
+
+type kexDHGexInitMsg struct {
+	X *big.Int `sshtype:"32"`
+}
+
+const msgKexDHGexReply = 33
+
+type kexDHGexReplyMsg struct {
+	HostKey   []byte `sshtype:"33"`
+	Y         *big.Int
+	Signature []byte
+}
+
+const msgKexDHGexRequest = 34
+
+type kexDHGexRequestMsg struct {
+	MinBits      uint32 `sshtype:"34"`
+	PreferedBits uint32
+	MaxBits      uint32
+}
+
+// See RFC 4253, section 10.
+const msgServiceRequest = 5
+
+type serviceRequestMsg struct {
+	Service string `sshtype:"5"`
+}
+
+// See RFC 4253, section 10.
+const msgServiceAccept = 6
+
+type serviceAcceptMsg struct {
+	Service string `sshtype:"6"`
+}
+
+// See RFC 8308, section 2.3
+const msgExtInfo = 7
+
+type extInfoMsg struct {
+	NumExtensions uint32 `sshtype:"7"`
+	Payload       []byte `ssh:"rest"`
+}
+
+// See RFC 4252, section 5.
+const msgUserAuthRequest = 50
+
+type userAuthRequestMsg struct {
+	User    string `sshtype:"50"`
+	Service string
+	Method  string
+	Payload []byte `ssh:"rest"`
+}
+
+// Used for debug printouts of packets.
+type userAuthSuccessMsg struct {
+}
+
+// See RFC 4252, section 5.1
+const msgUserAuthFailure = 51
+
+type userAuthFailureMsg struct {
+	Methods        []string `sshtype:"51"`
+	PartialSuccess bool
+}
+
+// See RFC 4252, section 5.1
+const msgUserAuthSuccess = 52
+
+// See RFC 4252, section 5.4
+const msgUserAuthBanner = 53
+
+type userAuthBannerMsg struct {
+	Message string `sshtype:"53"`
+	// unused, but required to allow message parsing
+	Language string
+}
+
+// See RFC 4256, section 3.2
+const msgUserAuthInfoRequest = 60
+const msgUserAuthInfoResponse = 61
+
+type userAuthInfoRequestMsg struct {
+	Name        string `sshtype:"60"`
+	Instruction string
+	Language    string
+	NumPrompts  uint32
+	Prompts     []byte `ssh:"rest"`
+}
+
+// See RFC 4254, section 5.1.
+const msgChannelOpen = 90
+
+type channelOpenMsg struct {
+	ChanType         string `sshtype:"90"`
+	PeersID          uint32
+	PeersWindow      uint32
+	MaxPacketSize    uint32
+	TypeSpecificData []byte `ssh:"rest"`
+}
+
+const msgChannelExtendedData = 95
+const msgChannelData = 94
+
+// Used for debug print outs of packets.
+type channelDataMsg struct {
+	PeersID uint32 `sshtype:"94"`
+	Length  uint32
+	Rest    []byte `ssh:"rest"`
+}
+
+// See RFC 4254, section 5.1.
+const msgChannelOpenConfirm = 91
+
+type channelOpenConfirmMsg struct {
+	PeersID          uint32 `sshtype:"91"`
+	MyID             uint32
+	MyWindow         uint32
+	MaxPacketSize    uint32
+	TypeSpecificData []byte `ssh:"rest"`
+}
+
+// See RFC 4254, section 5.1.
+const msgChannelOpenFailure = 92
+
+type channelOpenFailureMsg struct {
+	PeersID  uint32 `sshtype:"92"`
+	Reason   RejectionReason
+	Message  string
+	Language string
+}
+
+const msgChannelRequest = 98
+
+type channelRequestMsg struct {
+	PeersID             uint32 `sshtype:"98"`
+	Request             string
+	WantReply           bool
+	RequestSpecificData []byte `ssh:"rest"`
+}
+
+// See RFC 4254, section 5.4.
+const msgChannelSuccess = 99
+
+type channelRequestSuccessMsg struct {
+	PeersID uint32 `sshtype:"99"`
+}
+
+// See RFC 4254, section 5.4.
+const msgChannelFailure = 100
+
+type channelRequestFailureMsg struct {
+	PeersID uint32 `sshtype:"100"`
+}
+
+// See RFC 4254, section 5.3
+const msgChannelClose = 97
+
+type channelCloseMsg struct {
+	PeersID uint32 `sshtype:"97"`
+}
+
+// See RFC 4254, section 5.3
+const msgChannelEOF = 96
+
+type channelEOFMsg struct {
+	PeersID uint32 `sshtype:"96"`
+}
+
+// See RFC 4254, section 4
+const msgGlobalRequest = 80
+
+type globalRequestMsg struct {
+	Type      string `sshtype:"80"`
+	WantReply bool
+	Data      []byte `ssh:"rest"`
+}
+
+// See RFC 4254, section 4
+const msgRequestSuccess = 81
+
+type globalRequestSuccessMsg struct {
+	Data []byte `ssh:"rest" sshtype:"81"`
+}
+
+// See RFC 4254, section 4
+const msgRequestFailure = 82
+
+type globalRequestFailureMsg struct {
+	Data []byte `ssh:"rest" sshtype:"82"`
+}
+
+// See RFC 4254, section 5.2
+const msgChannelWindowAdjust = 93
+
+type windowAdjustMsg struct {
+	PeersID         uint32 `sshtype:"93"`
+	AdditionalBytes uint32
+}
+
+// See RFC 4252, section 7
+const msgUserAuthPubKeyOk = 60
+
+type userAuthPubKeyOkMsg struct {
+	Algo   string `sshtype:"60"`
+	PubKey []byte
+}
+
+// See RFC 4462, section 3
+const msgUserAuthGSSAPIResponse = 60
+
+type userAuthGSSAPIResponse struct {
+	SupportMech []byte `sshtype:"60"`
+}
+
+const msgUserAuthGSSAPIToken = 61
+
+type userAuthGSSAPIToken struct {
+	Token []byte `sshtype:"61"`
+}
+
+const msgUserAuthGSSAPIMIC = 66
+
+type userAuthGSSAPIMIC struct {
+	MIC []byte `sshtype:"66"`
+}
+
+// See RFC 4462, section 3.9
+const msgUserAuthGSSAPIErrTok = 64
+
+type userAuthGSSAPIErrTok struct {
+	ErrorToken []byte `sshtype:"64"`
+}
+
+// See RFC 4462, section 3.8
+const msgUserAuthGSSAPIError = 65
+
+type userAuthGSSAPIError struct {
+	MajorStatus uint32 `sshtype:"65"`
+	MinorStatus uint32
+	Message     string
+	LanguageTag string
+}
+
+// Transport layer OpenSSH extension. See [PROTOCOL], section 1.9
+const msgPing = 192
+
+type pingMsg struct {
+	Data string `sshtype:"192"`
+}
+
+// Transport layer OpenSSH extension. See [PROTOCOL], section 1.9
+const msgPong = 193
+
+type pongMsg struct {
+	Data string `sshtype:"193"`
+}
+
+// typeTags returns the possible type bytes for the given reflect.Type, which
+// should be a struct. The possible values are separated by a '|' character.
+func typeTags(structType reflect.Type) (tags []byte) {
+	tagStr := structType.Field(0).Tag.Get("sshtype")
+
+	for _, tag := range strings.Split(tagStr, "|") {
+		i, err := strconv.Atoi(tag)
+		if err == nil {
+			tags = append(tags, byte(i))
+		}
+	}
+
+	return tags
+}
+
+func fieldError(t reflect.Type, field int, problem string) error {
+	if problem != "" {
+		problem = ": " + problem
+	}
+	return fmt.Errorf("ssh: unmarshal error for field %s of type %s%s", t.Field(field).Name, t.Name(), problem)
+}
+
+var errShortRead = errors.New("ssh: short read")
+
+// Unmarshal parses data in SSH wire format into a structure. The out
+// argument should be a pointer to struct. If the first member of the
+// struct has the "sshtype" tag set to a '|'-separated set of numbers
+// in decimal, the packet must start with one of those numbers. In
+// case of error, Unmarshal returns a ParseError or
+// UnexpectedMessageError.
+func Unmarshal(data []byte, out interface{}) error {
+	v := reflect.ValueOf(out).Elem()
+	structType := v.Type()
+	expectedTypes := typeTags(structType)
+
+	var expectedType byte
+	if len(expectedTypes) > 0 {
+		expectedType = expectedTypes[0]
+	}
+
+	if len(data) == 0 {
+		return parseError(expectedType)
+	}
+
+	if len(expectedTypes) > 0 {
+		goodType := false
+		for _, e := range expectedTypes {
+			if e > 0 && data[0] == e {
+				goodType = true
+				break
+			}
+		}
+		if !goodType {
+			return fmt.Errorf("ssh: unexpected message type %d (expected one of %v)", data[0], expectedTypes)
+		}
+		data = data[1:]
+	}
+
+	var ok bool
+	for i := 0; i < v.NumField(); i++ {
+		field := v.Field(i)
+		t := field.Type()
+		switch t.Kind() {
+		case reflect.Bool:
+			if len(data) < 1 {
+				return errShortRead
+			}
+			field.SetBool(data[0] != 0)
+			data = data[1:]
+		case reflect.Array:
+			if t.Elem().Kind() != reflect.Uint8 {
+				return fieldError(structType, i, "array of unsupported type")
+			}
+			if len(data) < t.Len() {
+				return errShortRead
+			}
+			for j, n := 0, t.Len(); j < n; j++ {
+				field.Index(j).Set(reflect.ValueOf(data[j]))
+			}
+			data = data[t.Len():]
+		case reflect.Uint64:
+			var u64 uint64
+			if u64, data, ok = parseUint64(data); !ok {
+				return errShortRead
+			}
+			field.SetUint(u64)
+		case reflect.Uint32:
+			var u32 uint32
+			if u32, data, ok = parseUint32(data); !ok {
+				return errShortRead
+			}
+			field.SetUint(uint64(u32))
+		case reflect.Uint8:
+			if len(data) < 1 {
+				return errShortRead
+			}
+			field.SetUint(uint64(data[0]))
+			data = data[1:]
+		case reflect.String:
+			var s []byte
+			if s, data, ok = parseString(data); !ok {
+				return fieldError(structType, i, "")
+			}
+			field.SetString(string(s))
+		case reflect.Slice:
+			switch t.Elem().Kind() {
+			case reflect.Uint8:
+				if structType.Field(i).Tag.Get("ssh") == "rest" {
+					field.Set(reflect.ValueOf(data))
+					data = nil
+				} else {
+					var s []byte
+					if s, data, ok = parseString(data); !ok {
+						return errShortRead
+					}
+					field.Set(reflect.ValueOf(s))
+				}
+			case reflect.String:
+				var nl []string
+				if nl, data, ok = parseNameList(data); !ok {
+					return errShortRead
+				}
+				field.Set(reflect.ValueOf(nl))
+			default:
+				return fieldError(structType, i, "slice of unsupported type")
+			}
+		case reflect.Ptr:
+			if t == bigIntType {
+				var n *big.Int
+				if n, data, ok = parseInt(data); !ok {
+					return errShortRead
+				}
+				field.Set(reflect.ValueOf(n))
+			} else {
+				return fieldError(structType, i, "pointer to unsupported type")
+			}
+		default:
+			return fieldError(structType, i, fmt.Sprintf("unsupported type: %v", t))
+		}
+	}
+
+	if len(data) != 0 {
+		return parseError(expectedType)
+	}
+
+	return nil
+}
+
+// Marshal serializes the message in msg to SSH wire format.  The msg
+// argument should be a struct or pointer to struct. If the first
+// member has the "sshtype" tag set to a number in decimal, that
+// number is prepended to the result. If the last of member has the
+// "ssh" tag set to "rest", its contents are appended to the output.
+func Marshal(msg interface{}) []byte {
+	out := make([]byte, 0, 64)
+	return marshalStruct(out, msg)
+}
+
+func marshalStruct(out []byte, msg interface{}) []byte {
+	v := reflect.Indirect(reflect.ValueOf(msg))
+	msgTypes := typeTags(v.Type())
+	if len(msgTypes) > 0 {
+		out = append(out, msgTypes[0])
+	}
+
+	for i, n := 0, v.NumField(); i < n; i++ {
+		field := v.Field(i)
+		switch t := field.Type(); t.Kind() {
+		case reflect.Bool:
+			var v uint8
+			if field.Bool() {
+				v = 1
+			}
+			out = append(out, v)
+		case reflect.Array:
+			if t.Elem().Kind() != reflect.Uint8 {
+				panic(fmt.Sprintf("array of non-uint8 in field %d: %T", i, field.Interface()))
+			}
+			for j, l := 0, t.Len(); j < l; j++ {
+				out = append(out, uint8(field.Index(j).Uint()))
+			}
+		case reflect.Uint32:
+			out = appendU32(out, uint32(field.Uint()))
+		case reflect.Uint64:
+			out = appendU64(out, uint64(field.Uint()))
+		case reflect.Uint8:
+			out = append(out, uint8(field.Uint()))
+		case reflect.String:
+			s := field.String()
+			out = appendInt(out, len(s))
+			out = append(out, s...)
+		case reflect.Slice:
+			switch t.Elem().Kind() {
+			case reflect.Uint8:
+				if v.Type().Field(i).Tag.Get("ssh") != "rest" {
+					out = appendInt(out, field.Len())
+				}
+				out = append(out, field.Bytes()...)
+			case reflect.String:
+				offset := len(out)
+				out = appendU32(out, 0)
+				if n := field.Len(); n > 0 {
+					for j := 0; j < n; j++ {
+						f := field.Index(j)
+						if j != 0 {
+							out = append(out, ',')
+						}
+						out = append(out, f.String()...)
+					}
+					// overwrite length value
+					binary.BigEndian.PutUint32(out[offset:], uint32(len(out)-offset-4))
+				}
+			default:
+				panic(fmt.Sprintf("slice of unknown type in field %d: %T", i, field.Interface()))
+			}
+		case reflect.Ptr:
+			if t == bigIntType {
+				var n *big.Int
+				nValue := reflect.ValueOf(&n)
+				nValue.Elem().Set(field)
+				needed := intLength(n)
+				oldLength := len(out)
+
+				if cap(out)-len(out) < needed {
+					newOut := make([]byte, len(out), 2*(len(out)+needed))
+					copy(newOut, out)
+					out = newOut
+				}
+				out = out[:oldLength+needed]
+				marshalInt(out[oldLength:], n)
+			} else {
+				panic(fmt.Sprintf("pointer to unknown type in field %d: %T", i, field.Interface()))
+			}
+		}
+	}
+
+	return out
+}
+
+var bigOne = big.NewInt(1)
+
+func parseString(in []byte) (out, rest []byte, ok bool) {
+	if len(in) < 4 {
+		return
+	}
+	length := binary.BigEndian.Uint32(in)
+	in = in[4:]
+	if uint32(len(in)) < length {
+		return
+	}
+	out = in[:length]
+	rest = in[length:]
+	ok = true
+	return
+}
+
+var (
+	comma         = []byte{','}
+	emptyNameList = []string{}
+)
+
+func parseNameList(in []byte) (out []string, rest []byte, ok bool) {
+	contents, rest, ok := parseString(in)
+	if !ok {
+		return
+	}
+	if len(contents) == 0 {
+		out = emptyNameList
+		return
+	}
+	parts := bytes.Split(contents, comma)
+	out = make([]string, len(parts))
+	for i, part := range parts {
+		out[i] = string(part)
+	}
+	return
+}
+
+func parseInt(in []byte) (out *big.Int, rest []byte, ok bool) {
+	contents, rest, ok := parseString(in)
+	if !ok {
+		return
+	}
+	out = new(big.Int)
+
+	if len(contents) > 0 && contents[0]&0x80 == 0x80 {
+		// This is a negative number
+		notBytes := make([]byte, len(contents))
+		for i := range notBytes {
+			notBytes[i] = ^contents[i]
+		}
+		out.SetBytes(notBytes)
+		out.Add(out, bigOne)
+		out.Neg(out)
+	} else {
+		// Positive number
+		out.SetBytes(contents)
+	}
+	ok = true
+	return
+}
+
+func parseUint32(in []byte) (uint32, []byte, bool) {
+	if len(in) < 4 {
+		return 0, nil, false
+	}
+	return binary.BigEndian.Uint32(in), in[4:], true
+}
+
+func parseUint64(in []byte) (uint64, []byte, bool) {
+	if len(in) < 8 {
+		return 0, nil, false
+	}
+	return binary.BigEndian.Uint64(in), in[8:], true
+}
+
+func intLength(n *big.Int) int {
+	length := 4 /* length bytes */
+	if n.Sign() < 0 {
+		nMinus1 := new(big.Int).Neg(n)
+		nMinus1.Sub(nMinus1, bigOne)
+		bitLen := nMinus1.BitLen()
+		if bitLen%8 == 0 {
+			// The number will need 0xff padding
+			length++
+		}
+		length += (bitLen + 7) / 8
+	} else if n.Sign() == 0 {
+		// A zero is the zero length string
+	} else {
+		bitLen := n.BitLen()
+		if bitLen%8 == 0 {
+			// The number will need 0x00 padding
+			length++
+		}
+		length += (bitLen + 7) / 8
+	}
+
+	return length
+}
+
+func marshalUint32(to []byte, n uint32) []byte {
+	binary.BigEndian.PutUint32(to, n)
+	return to[4:]
+}
+
+func marshalUint64(to []byte, n uint64) []byte {
+	binary.BigEndian.PutUint64(to, n)
+	return to[8:]
+}
+
+func marshalInt(to []byte, n *big.Int) []byte {
+	lengthBytes := to
+	to = to[4:]
+	length := 0
+
+	if n.Sign() < 0 {
+		// A negative number has to be converted to two's-complement
+		// form. So we'll subtract 1 and invert. If the
+		// most-significant-bit isn't set then we'll need to pad the
+		// beginning with 0xff in order to keep the number negative.
+		nMinus1 := new(big.Int).Neg(n)
+		nMinus1.Sub(nMinus1, bigOne)
+		bytes := nMinus1.Bytes()
+		for i := range bytes {
+			bytes[i] ^= 0xff
+		}
+		if len(bytes) == 0 || bytes[0]&0x80 == 0 {
+			to[0] = 0xff
+			to = to[1:]
+			length++
+		}
+		nBytes := copy(to, bytes)
+		to = to[nBytes:]
+		length += nBytes
+	} else if n.Sign() == 0 {
+		// A zero is the zero length string
+	} else {
+		bytes := n.Bytes()
+		if len(bytes) > 0 && bytes[0]&0x80 != 0 {
+			// We'll have to pad this with a 0x00 in order to
+			// stop it looking like a negative number.
+			to[0] = 0
+			to = to[1:]
+			length++
+		}
+		nBytes := copy(to, bytes)
+		to = to[nBytes:]
+		length += nBytes
+	}
+
+	lengthBytes[0] = byte(length >> 24)
+	lengthBytes[1] = byte(length >> 16)
+	lengthBytes[2] = byte(length >> 8)
+	lengthBytes[3] = byte(length)
+	return to
+}
+
+func writeInt(w io.Writer, n *big.Int) {
+	length := intLength(n)
+	buf := make([]byte, length)
+	marshalInt(buf, n)
+	w.Write(buf)
+}
+
+func writeString(w io.Writer, s []byte) {
+	var lengthBytes [4]byte
+	lengthBytes[0] = byte(len(s) >> 24)
+	lengthBytes[1] = byte(len(s) >> 16)
+	lengthBytes[2] = byte(len(s) >> 8)
+	lengthBytes[3] = byte(len(s))
+	w.Write(lengthBytes[:])
+	w.Write(s)
+}
+
+func stringLength(n int) int {
+	return 4 + n
+}
+
+func marshalString(to []byte, s []byte) []byte {
+	to[0] = byte(len(s) >> 24)
+	to[1] = byte(len(s) >> 16)
+	to[2] = byte(len(s) >> 8)
+	to[3] = byte(len(s))
+	to = to[4:]
+	copy(to, s)
+	return to[len(s):]
+}
+
+var bigIntType = reflect.TypeOf((*big.Int)(nil))
+
+// Decode a packet into its corresponding message.
+func decode(packet []byte) (interface{}, error) {
+	var msg interface{}
+	switch packet[0] {
+	case msgDisconnect:
+		msg = new(disconnectMsg)
+	case msgServiceRequest:
+		msg = new(serviceRequestMsg)
+	case msgServiceAccept:
+		msg = new(serviceAcceptMsg)
+	case msgExtInfo:
+		msg = new(extInfoMsg)
+	case msgKexInit:
+		msg = new(kexInitMsg)
+	case msgKexDHInit:
+		msg = new(kexDHInitMsg)
+	case msgKexDHReply:
+		msg = new(kexDHReplyMsg)
+	case msgUserAuthRequest:
+		msg = new(userAuthRequestMsg)
+	case msgUserAuthSuccess:
+		return new(userAuthSuccessMsg), nil
+	case msgUserAuthFailure:
+		msg = new(userAuthFailureMsg)
+	case msgUserAuthPubKeyOk:
+		msg = new(userAuthPubKeyOkMsg)
+	case msgGlobalRequest:
+		msg = new(globalRequestMsg)
+	case msgRequestSuccess:
+		msg = new(globalRequestSuccessMsg)
+	case msgRequestFailure:
+		msg = new(globalRequestFailureMsg)
+	case msgChannelOpen:
+		msg = new(channelOpenMsg)
+	case msgChannelData:
+		msg = new(channelDataMsg)
+	case msgChannelOpenConfirm:
+		msg = new(channelOpenConfirmMsg)
+	case msgChannelOpenFailure:
+		msg = new(channelOpenFailureMsg)
+	case msgChannelWindowAdjust:
+		msg = new(windowAdjustMsg)
+	case msgChannelEOF:
+		msg = new(channelEOFMsg)
+	case msgChannelClose:
+		msg = new(channelCloseMsg)
+	case msgChannelRequest:
+		msg = new(channelRequestMsg)
+	case msgChannelSuccess:
+		msg = new(channelRequestSuccessMsg)
+	case msgChannelFailure:
+		msg = new(channelRequestFailureMsg)
+	case msgUserAuthGSSAPIToken:
+		msg = new(userAuthGSSAPIToken)
+	case msgUserAuthGSSAPIMIC:
+		msg = new(userAuthGSSAPIMIC)
+	case msgUserAuthGSSAPIErrTok:
+		msg = new(userAuthGSSAPIErrTok)
+	case msgUserAuthGSSAPIError:
+		msg = new(userAuthGSSAPIError)
+	default:
+		return nil, unexpectedMessageError(0, packet[0])
+	}
+	if err := Unmarshal(packet, msg); err != nil {
+		return nil, err
+	}
+	return msg, nil
+}
+
+var packetTypeNames = map[byte]string{
+	msgDisconnect:          "disconnectMsg",
+	msgServiceRequest:      "serviceRequestMsg",
+	msgServiceAccept:       "serviceAcceptMsg",
+	msgExtInfo:             "extInfoMsg",
+	msgKexInit:             "kexInitMsg",
+	msgKexDHInit:           "kexDHInitMsg",
+	msgKexDHReply:          "kexDHReplyMsg",
+	msgUserAuthRequest:     "userAuthRequestMsg",
+	msgUserAuthSuccess:     "userAuthSuccessMsg",
+	msgUserAuthFailure:     "userAuthFailureMsg",
+	msgUserAuthPubKeyOk:    "userAuthPubKeyOkMsg",
+	msgGlobalRequest:       "globalRequestMsg",
+	msgRequestSuccess:      "globalRequestSuccessMsg",
+	msgRequestFailure:      "globalRequestFailureMsg",
+	msgChannelOpen:         "channelOpenMsg",
+	msgChannelData:         "channelDataMsg",
+	msgChannelOpenConfirm:  "channelOpenConfirmMsg",
+	msgChannelOpenFailure:  "channelOpenFailureMsg",
+	msgChannelWindowAdjust: "windowAdjustMsg",
+	msgChannelEOF:          "channelEOFMsg",
+	msgChannelClose:        "channelCloseMsg",
+	msgChannelRequest:      "channelRequestMsg",
+	msgChannelSuccess:      "channelRequestSuccessMsg",
+	msgChannelFailure:      "channelRequestFailureMsg",
+}
diff --git a/vendor/golang.org/x/crypto/ssh/mux.go b/vendor/golang.org/x/crypto/ssh/mux.go
new file mode 100644
index 000000000..d2d24c635
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/mux.go
@@ -0,0 +1,357 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"log"
+	"sync"
+	"sync/atomic"
+)
+
+// debugMux, if set, causes messages in the connection protocol to be
+// logged.
+const debugMux = false
+
+// chanList is a thread safe channel list.
+type chanList struct {
+	// protects concurrent access to chans
+	sync.Mutex
+
+	// chans are indexed by the local id of the channel, which the
+	// other side should send in the PeersId field.
+	chans []*channel
+
+	// This is a debugging aid: it offsets all IDs by this
+	// amount. This helps distinguish otherwise identical
+	// server/client muxes
+	offset uint32
+}
+
+// Assigns a channel ID to the given channel.
+func (c *chanList) add(ch *channel) uint32 {
+	c.Lock()
+	defer c.Unlock()
+	for i := range c.chans {
+		if c.chans[i] == nil {
+			c.chans[i] = ch
+			return uint32(i) + c.offset
+		}
+	}
+	c.chans = append(c.chans, ch)
+	return uint32(len(c.chans)-1) + c.offset
+}
+
+// getChan returns the channel for the given ID.
+func (c *chanList) getChan(id uint32) *channel {
+	id -= c.offset
+
+	c.Lock()
+	defer c.Unlock()
+	if id < uint32(len(c.chans)) {
+		return c.chans[id]
+	}
+	return nil
+}
+
+func (c *chanList) remove(id uint32) {
+	id -= c.offset
+	c.Lock()
+	if id < uint32(len(c.chans)) {
+		c.chans[id] = nil
+	}
+	c.Unlock()
+}
+
+// dropAll forgets all channels it knows, returning them in a slice.
+func (c *chanList) dropAll() []*channel {
+	c.Lock()
+	defer c.Unlock()
+	var r []*channel
+
+	for _, ch := range c.chans {
+		if ch == nil {
+			continue
+		}
+		r = append(r, ch)
+	}
+	c.chans = nil
+	return r
+}
+
+// mux represents the state for the SSH connection protocol, which
+// multiplexes many channels onto a single packet transport.
+type mux struct {
+	conn     packetConn
+	chanList chanList
+
+	incomingChannels chan NewChannel
+
+	globalSentMu     sync.Mutex
+	globalResponses  chan interface{}
+	incomingRequests chan *Request
+
+	errCond *sync.Cond
+	err     error
+}
+
+// When debugging, each new chanList instantiation has a different
+// offset.
+var globalOff uint32
+
+func (m *mux) Wait() error {
+	m.errCond.L.Lock()
+	defer m.errCond.L.Unlock()
+	for m.err == nil {
+		m.errCond.Wait()
+	}
+	return m.err
+}
+
+// newMux returns a mux that runs over the given connection.
+func newMux(p packetConn) *mux {
+	m := &mux{
+		conn:             p,
+		incomingChannels: make(chan NewChannel, chanSize),
+		globalResponses:  make(chan interface{}, 1),
+		incomingRequests: make(chan *Request, chanSize),
+		errCond:          newCond(),
+	}
+	if debugMux {
+		m.chanList.offset = atomic.AddUint32(&globalOff, 1)
+	}
+
+	go m.loop()
+	return m
+}
+
+func (m *mux) sendMessage(msg interface{}) error {
+	p := Marshal(msg)
+	if debugMux {
+		log.Printf("send global(%d): %#v", m.chanList.offset, msg)
+	}
+	return m.conn.writePacket(p)
+}
+
+func (m *mux) SendRequest(name string, wantReply bool, payload []byte) (bool, []byte, error) {
+	if wantReply {
+		m.globalSentMu.Lock()
+		defer m.globalSentMu.Unlock()
+	}
+
+	if err := m.sendMessage(globalRequestMsg{
+		Type:      name,
+		WantReply: wantReply,
+		Data:      payload,
+	}); err != nil {
+		return false, nil, err
+	}
+
+	if !wantReply {
+		return false, nil, nil
+	}
+
+	msg, ok := <-m.globalResponses
+	if !ok {
+		return false, nil, io.EOF
+	}
+	switch msg := msg.(type) {
+	case *globalRequestFailureMsg:
+		return false, msg.Data, nil
+	case *globalRequestSuccessMsg:
+		return true, msg.Data, nil
+	default:
+		return false, nil, fmt.Errorf("ssh: unexpected response to request: %#v", msg)
+	}
+}
+
+// ackRequest must be called after processing a global request that
+// has WantReply set.
+func (m *mux) ackRequest(ok bool, data []byte) error {
+	if ok {
+		return m.sendMessage(globalRequestSuccessMsg{Data: data})
+	}
+	return m.sendMessage(globalRequestFailureMsg{Data: data})
+}
+
+func (m *mux) Close() error {
+	return m.conn.Close()
+}
+
+// loop runs the connection machine. It will process packets until an
+// error is encountered. To synchronize on loop exit, use mux.Wait.
+func (m *mux) loop() {
+	var err error
+	for err == nil {
+		err = m.onePacket()
+	}
+
+	for _, ch := range m.chanList.dropAll() {
+		ch.close()
+	}
+
+	close(m.incomingChannels)
+	close(m.incomingRequests)
+	close(m.globalResponses)
+
+	m.conn.Close()
+
+	m.errCond.L.Lock()
+	m.err = err
+	m.errCond.Broadcast()
+	m.errCond.L.Unlock()
+
+	if debugMux {
+		log.Println("loop exit", err)
+	}
+}
+
+// onePacket reads and processes one packet.
+func (m *mux) onePacket() error {
+	packet, err := m.conn.readPacket()
+	if err != nil {
+		return err
+	}
+
+	if debugMux {
+		if packet[0] == msgChannelData || packet[0] == msgChannelExtendedData {
+			log.Printf("decoding(%d): data packet - %d bytes", m.chanList.offset, len(packet))
+		} else {
+			p, _ := decode(packet)
+			log.Printf("decoding(%d): %d %#v - %d bytes", m.chanList.offset, packet[0], p, len(packet))
+		}
+	}
+
+	switch packet[0] {
+	case msgChannelOpen:
+		return m.handleChannelOpen(packet)
+	case msgGlobalRequest, msgRequestSuccess, msgRequestFailure:
+		return m.handleGlobalPacket(packet)
+	case msgPing:
+		var msg pingMsg
+		if err := Unmarshal(packet, &msg); err != nil {
+			return fmt.Errorf("failed to unmarshal ping@openssh.com message: %w", err)
+		}
+		return m.sendMessage(pongMsg(msg))
+	}
+
+	// assume a channel packet.
+	if len(packet) < 5 {
+		return parseError(packet[0])
+	}
+	id := binary.BigEndian.Uint32(packet[1:])
+	ch := m.chanList.getChan(id)
+	if ch == nil {
+		return m.handleUnknownChannelPacket(id, packet)
+	}
+
+	return ch.handlePacket(packet)
+}
+
+func (m *mux) handleGlobalPacket(packet []byte) error {
+	msg, err := decode(packet)
+	if err != nil {
+		return err
+	}
+
+	switch msg := msg.(type) {
+	case *globalRequestMsg:
+		m.incomingRequests <- &Request{
+			Type:      msg.Type,
+			WantReply: msg.WantReply,
+			Payload:   msg.Data,
+			mux:       m,
+		}
+	case *globalRequestSuccessMsg, *globalRequestFailureMsg:
+		m.globalResponses <- msg
+	default:
+		panic(fmt.Sprintf("not a global message %#v", msg))
+	}
+
+	return nil
+}
+
+// handleChannelOpen schedules a channel to be Accept()ed.
+func (m *mux) handleChannelOpen(packet []byte) error {
+	var msg channelOpenMsg
+	if err := Unmarshal(packet, &msg); err != nil {
+		return err
+	}
+
+	if msg.MaxPacketSize < minPacketLength || msg.MaxPacketSize > 1<<31 {
+		failMsg := channelOpenFailureMsg{
+			PeersID:  msg.PeersID,
+			Reason:   ConnectionFailed,
+			Message:  "invalid request",
+			Language: "en_US.UTF-8",
+		}
+		return m.sendMessage(failMsg)
+	}
+
+	c := m.newChannel(msg.ChanType, channelInbound, msg.TypeSpecificData)
+	c.remoteId = msg.PeersID
+	c.maxRemotePayload = msg.MaxPacketSize
+	c.remoteWin.add(msg.PeersWindow)
+	m.incomingChannels <- c
+	return nil
+}
+
+func (m *mux) OpenChannel(chanType string, extra []byte) (Channel, <-chan *Request, error) {
+	ch, err := m.openChannel(chanType, extra)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return ch, ch.incomingRequests, nil
+}
+
+func (m *mux) openChannel(chanType string, extra []byte) (*channel, error) {
+	ch := m.newChannel(chanType, channelOutbound, extra)
+
+	ch.maxIncomingPayload = channelMaxPacket
+
+	open := channelOpenMsg{
+		ChanType:         chanType,
+		PeersWindow:      ch.myWindow,
+		MaxPacketSize:    ch.maxIncomingPayload,
+		TypeSpecificData: extra,
+		PeersID:          ch.localId,
+	}
+	if err := m.sendMessage(open); err != nil {
+		return nil, err
+	}
+
+	switch msg := (<-ch.msg).(type) {
+	case *channelOpenConfirmMsg:
+		return ch, nil
+	case *channelOpenFailureMsg:
+		return nil, &OpenChannelError{msg.Reason, msg.Message}
+	default:
+		return nil, fmt.Errorf("ssh: unexpected packet in response to channel open: %T", msg)
+	}
+}
+
+func (m *mux) handleUnknownChannelPacket(id uint32, packet []byte) error {
+	msg, err := decode(packet)
+	if err != nil {
+		return err
+	}
+
+	switch msg := msg.(type) {
+	// RFC 4254 section 5.4 says unrecognized channel requests should
+	// receive a failure response.
+	case *channelRequestMsg:
+		if msg.WantReply {
+			return m.sendMessage(channelRequestFailureMsg{
+				PeersID: msg.PeersID,
+			})
+		}
+		return nil
+	default:
+		return fmt.Errorf("ssh: invalid channel %d", id)
+	}
+}
diff --git a/vendor/golang.org/x/crypto/ssh/server.go b/vendor/golang.org/x/crypto/ssh/server.go
new file mode 100644
index 000000000..e2ae4f891
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/server.go
@@ -0,0 +1,872 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strings"
+)
+
+// The Permissions type holds fine-grained permissions that are
+// specific to a user or a specific authentication method for a user.
+// The Permissions value for a successful authentication attempt is
+// available in ServerConn, so it can be used to pass information from
+// the user-authentication phase to the application layer.
+type Permissions struct {
+	// CriticalOptions indicate restrictions to the default
+	// permissions, and are typically used in conjunction with
+	// user certificates. The standard for SSH certificates
+	// defines "force-command" (only allow the given command to
+	// execute) and "source-address" (only allow connections from
+	// the given address). The SSH package currently only enforces
+	// the "source-address" critical option. It is up to server
+	// implementations to enforce other critical options, such as
+	// "force-command", by checking them after the SSH handshake
+	// is successful. In general, SSH servers should reject
+	// connections that specify critical options that are unknown
+	// or not supported.
+	CriticalOptions map[string]string
+
+	// Extensions are extra functionality that the server may
+	// offer on authenticated connections. Lack of support for an
+	// extension does not preclude authenticating a user. Common
+	// extensions are "permit-agent-forwarding",
+	// "permit-X11-forwarding". The Go SSH library currently does
+	// not act on any extension, and it is up to server
+	// implementations to honor them. Extensions can be used to
+	// pass data from the authentication callbacks to the server
+	// application layer.
+	Extensions map[string]string
+}
+
+type GSSAPIWithMICConfig struct {
+	// AllowLogin, must be set, is called when gssapi-with-mic
+	// authentication is selected (RFC 4462 section 3). The srcName is from the
+	// results of the GSS-API authentication. The format is username@DOMAIN.
+	// GSSAPI just guarantees to the server who the user is, but not if they can log in, and with what permissions.
+	// This callback is called after the user identity is established with GSSAPI to decide if the user can login with
+	// which permissions. If the user is allowed to login, it should return a nil error.
+	AllowLogin func(conn ConnMetadata, srcName string) (*Permissions, error)
+
+	// Server must be set. It's the implementation
+	// of the GSSAPIServer interface. See GSSAPIServer interface for details.
+	Server GSSAPIServer
+}
+
+// ServerConfig holds server specific configuration data.
+type ServerConfig struct {
+	// Config contains configuration shared between client and server.
+	Config
+
+	// PublicKeyAuthAlgorithms specifies the supported client public key
+	// authentication algorithms. Note that this should not include certificate
+	// types since those use the underlying algorithm. This list is sent to the
+	// client if it supports the server-sig-algs extension. Order is irrelevant.
+	// If unspecified then a default set of algorithms is used.
+	PublicKeyAuthAlgorithms []string
+
+	hostKeys []Signer
+
+	// NoClientAuth is true if clients are allowed to connect without
+	// authenticating.
+	// To determine NoClientAuth at runtime, set NoClientAuth to true
+	// and the optional NoClientAuthCallback to a non-nil value.
+	NoClientAuth bool
+
+	// NoClientAuthCallback, if non-nil, is called when a user
+	// attempts to authenticate with auth method "none".
+	// NoClientAuth must also be set to true for this be used, or
+	// this func is unused.
+	NoClientAuthCallback func(ConnMetadata) (*Permissions, error)
+
+	// MaxAuthTries specifies the maximum number of authentication attempts
+	// permitted per connection. If set to a negative number, the number of
+	// attempts are unlimited. If set to zero, the number of attempts are limited
+	// to 6.
+	MaxAuthTries int
+
+	// PasswordCallback, if non-nil, is called when a user
+	// attempts to authenticate using a password.
+	PasswordCallback func(conn ConnMetadata, password []byte) (*Permissions, error)
+
+	// PublicKeyCallback, if non-nil, is called when a client
+	// offers a public key for authentication. It must return a nil error
+	// if the given public key can be used to authenticate the
+	// given user. For example, see CertChecker.Authenticate. A
+	// call to this function does not guarantee that the key
+	// offered is in fact used to authenticate. To record any data
+	// depending on the public key, store it inside a
+	// Permissions.Extensions entry.
+	PublicKeyCallback func(conn ConnMetadata, key PublicKey) (*Permissions, error)
+
+	// KeyboardInteractiveCallback, if non-nil, is called when
+	// keyboard-interactive authentication is selected (RFC
+	// 4256). The client object's Challenge function should be
+	// used to query the user. The callback may offer multiple
+	// Challenge rounds. To avoid information leaks, the client
+	// should be presented a challenge even if the user is
+	// unknown.
+	KeyboardInteractiveCallback func(conn ConnMetadata, client KeyboardInteractiveChallenge) (*Permissions, error)
+
+	// AuthLogCallback, if non-nil, is called to log all authentication
+	// attempts.
+	AuthLogCallback func(conn ConnMetadata, method string, err error)
+
+	// ServerVersion is the version identification string to announce in
+	// the public handshake.
+	// If empty, a reasonable default is used.
+	// Note that RFC 4253 section 4.2 requires that this string start with
+	// "SSH-2.0-".
+	ServerVersion string
+
+	// BannerCallback, if present, is called and the return string is sent to
+	// the client after key exchange completed but before authentication.
+	BannerCallback func(conn ConnMetadata) string
+
+	// GSSAPIWithMICConfig includes gssapi server and callback, which if both non-nil, is used
+	// when gssapi-with-mic authentication is selected (RFC 4462 section 3).
+	GSSAPIWithMICConfig *GSSAPIWithMICConfig
+}
+
+// AddHostKey adds a private key as a host key. If an existing host
+// key exists with the same public key format, it is replaced. Each server
+// config must have at least one host key.
+func (s *ServerConfig) AddHostKey(key Signer) {
+	for i, k := range s.hostKeys {
+		if k.PublicKey().Type() == key.PublicKey().Type() {
+			s.hostKeys[i] = key
+			return
+		}
+	}
+
+	s.hostKeys = append(s.hostKeys, key)
+}
+
+// cachedPubKey contains the results of querying whether a public key is
+// acceptable for a user.
+type cachedPubKey struct {
+	user       string
+	pubKeyData []byte
+	result     error
+	perms      *Permissions
+}
+
+const maxCachedPubKeys = 16
+
+// pubKeyCache caches tests for public keys.  Since SSH clients
+// will query whether a public key is acceptable before attempting to
+// authenticate with it, we end up with duplicate queries for public
+// key validity.  The cache only applies to a single ServerConn.
+type pubKeyCache struct {
+	keys []cachedPubKey
+}
+
+// get returns the result for a given user/algo/key tuple.
+func (c *pubKeyCache) get(user string, pubKeyData []byte) (cachedPubKey, bool) {
+	for _, k := range c.keys {
+		if k.user == user && bytes.Equal(k.pubKeyData, pubKeyData) {
+			return k, true
+		}
+	}
+	return cachedPubKey{}, false
+}
+
+// add adds the given tuple to the cache.
+func (c *pubKeyCache) add(candidate cachedPubKey) {
+	if len(c.keys) < maxCachedPubKeys {
+		c.keys = append(c.keys, candidate)
+	}
+}
+
+// ServerConn is an authenticated SSH connection, as seen from the
+// server
+type ServerConn struct {
+	Conn
+
+	// If the succeeding authentication callback returned a
+	// non-nil Permissions pointer, it is stored here.
+	Permissions *Permissions
+}
+
+// NewServerConn starts a new SSH server with c as the underlying
+// transport.  It starts with a handshake and, if the handshake is
+// unsuccessful, it closes the connection and returns an error.  The
+// Request and NewChannel channels must be serviced, or the connection
+// will hang.
+//
+// The returned error may be of type *ServerAuthError for
+// authentication errors.
+func NewServerConn(c net.Conn, config *ServerConfig) (*ServerConn, <-chan NewChannel, <-chan *Request, error) {
+	fullConf := *config
+	fullConf.SetDefaults()
+	if fullConf.MaxAuthTries == 0 {
+		fullConf.MaxAuthTries = 6
+	}
+	if len(fullConf.PublicKeyAuthAlgorithms) == 0 {
+		fullConf.PublicKeyAuthAlgorithms = supportedPubKeyAuthAlgos
+	} else {
+		for _, algo := range fullConf.PublicKeyAuthAlgorithms {
+			if !contains(supportedPubKeyAuthAlgos, algo) {
+				c.Close()
+				return nil, nil, nil, fmt.Errorf("ssh: unsupported public key authentication algorithm %s", algo)
+			}
+		}
+	}
+	// Check if the config contains any unsupported key exchanges
+	for _, kex := range fullConf.KeyExchanges {
+		if _, ok := serverForbiddenKexAlgos[kex]; ok {
+			c.Close()
+			return nil, nil, nil, fmt.Errorf("ssh: unsupported key exchange %s for server", kex)
+		}
+	}
+
+	s := &connection{
+		sshConn: sshConn{conn: c},
+	}
+	perms, err := s.serverHandshake(&fullConf)
+	if err != nil {
+		c.Close()
+		return nil, nil, nil, err
+	}
+	return &ServerConn{s, perms}, s.mux.incomingChannels, s.mux.incomingRequests, nil
+}
+
+// signAndMarshal signs the data with the appropriate algorithm,
+// and serializes the result in SSH wire format. algo is the negotiate
+// algorithm and may be a certificate type.
+func signAndMarshal(k AlgorithmSigner, rand io.Reader, data []byte, algo string) ([]byte, error) {
+	sig, err := k.SignWithAlgorithm(rand, data, underlyingAlgo(algo))
+	if err != nil {
+		return nil, err
+	}
+
+	return Marshal(sig), nil
+}
+
+// handshake performs key exchange and user authentication.
+func (s *connection) serverHandshake(config *ServerConfig) (*Permissions, error) {
+	if len(config.hostKeys) == 0 {
+		return nil, errors.New("ssh: server has no host keys")
+	}
+
+	if !config.NoClientAuth && config.PasswordCallback == nil && config.PublicKeyCallback == nil &&
+		config.KeyboardInteractiveCallback == nil && (config.GSSAPIWithMICConfig == nil ||
+		config.GSSAPIWithMICConfig.AllowLogin == nil || config.GSSAPIWithMICConfig.Server == nil) {
+		return nil, errors.New("ssh: no authentication methods configured but NoClientAuth is also false")
+	}
+
+	if config.ServerVersion != "" {
+		s.serverVersion = []byte(config.ServerVersion)
+	} else {
+		s.serverVersion = []byte(packageVersion)
+	}
+	var err error
+	s.clientVersion, err = exchangeVersions(s.sshConn.conn, s.serverVersion)
+	if err != nil {
+		return nil, err
+	}
+
+	tr := newTransport(s.sshConn.conn, config.Rand, false /* not client */)
+	s.transport = newServerTransport(tr, s.clientVersion, s.serverVersion, config)
+
+	if err := s.transport.waitSession(); err != nil {
+		return nil, err
+	}
+
+	// We just did the key change, so the session ID is established.
+	s.sessionID = s.transport.getSessionID()
+
+	var packet []byte
+	if packet, err = s.transport.readPacket(); err != nil {
+		return nil, err
+	}
+
+	var serviceRequest serviceRequestMsg
+	if err = Unmarshal(packet, &serviceRequest); err != nil {
+		return nil, err
+	}
+	if serviceRequest.Service != serviceUserAuth {
+		return nil, errors.New("ssh: requested service '" + serviceRequest.Service + "' before authenticating")
+	}
+	serviceAccept := serviceAcceptMsg{
+		Service: serviceUserAuth,
+	}
+	if err := s.transport.writePacket(Marshal(&serviceAccept)); err != nil {
+		return nil, err
+	}
+
+	perms, err := s.serverAuthenticate(config)
+	if err != nil {
+		return nil, err
+	}
+	s.mux = newMux(s.transport)
+	return perms, err
+}
+
+func checkSourceAddress(addr net.Addr, sourceAddrs string) error {
+	if addr == nil {
+		return errors.New("ssh: no address known for client, but source-address match required")
+	}
+
+	tcpAddr, ok := addr.(*net.TCPAddr)
+	if !ok {
+		return fmt.Errorf("ssh: remote address %v is not an TCP address when checking source-address match", addr)
+	}
+
+	for _, sourceAddr := range strings.Split(sourceAddrs, ",") {
+		if allowedIP := net.ParseIP(sourceAddr); allowedIP != nil {
+			if allowedIP.Equal(tcpAddr.IP) {
+				return nil
+			}
+		} else {
+			_, ipNet, err := net.ParseCIDR(sourceAddr)
+			if err != nil {
+				return fmt.Errorf("ssh: error parsing source-address restriction %q: %v", sourceAddr, err)
+			}
+
+			if ipNet.Contains(tcpAddr.IP) {
+				return nil
+			}
+		}
+	}
+
+	return fmt.Errorf("ssh: remote address %v is not allowed because of source-address restriction", addr)
+}
+
+func gssExchangeToken(gssapiConfig *GSSAPIWithMICConfig, token []byte, s *connection,
+	sessionID []byte, userAuthReq userAuthRequestMsg) (authErr error, perms *Permissions, err error) {
+	gssAPIServer := gssapiConfig.Server
+	defer gssAPIServer.DeleteSecContext()
+	var srcName string
+	for {
+		var (
+			outToken     []byte
+			needContinue bool
+		)
+		outToken, srcName, needContinue, err = gssAPIServer.AcceptSecContext(token)
+		if err != nil {
+			return err, nil, nil
+		}
+		if len(outToken) != 0 {
+			if err := s.transport.writePacket(Marshal(&userAuthGSSAPIToken{
+				Token: outToken,
+			})); err != nil {
+				return nil, nil, err
+			}
+		}
+		if !needContinue {
+			break
+		}
+		packet, err := s.transport.readPacket()
+		if err != nil {
+			return nil, nil, err
+		}
+		userAuthGSSAPITokenReq := &userAuthGSSAPIToken{}
+		if err := Unmarshal(packet, userAuthGSSAPITokenReq); err != nil {
+			return nil, nil, err
+		}
+		token = userAuthGSSAPITokenReq.Token
+	}
+	packet, err := s.transport.readPacket()
+	if err != nil {
+		return nil, nil, err
+	}
+	userAuthGSSAPIMICReq := &userAuthGSSAPIMIC{}
+	if err := Unmarshal(packet, userAuthGSSAPIMICReq); err != nil {
+		return nil, nil, err
+	}
+	mic := buildMIC(string(sessionID), userAuthReq.User, userAuthReq.Service, userAuthReq.Method)
+	if err := gssAPIServer.VerifyMIC(mic, userAuthGSSAPIMICReq.MIC); err != nil {
+		return err, nil, nil
+	}
+	perms, authErr = gssapiConfig.AllowLogin(s, srcName)
+	return authErr, perms, nil
+}
+
+// isAlgoCompatible checks if the signature format is compatible with the
+// selected algorithm taking into account edge cases that occur with old
+// clients.
+func isAlgoCompatible(algo, sigFormat string) bool {
+	// Compatibility for old clients.
+	//
+	// For certificate authentication with OpenSSH 7.2-7.7 signature format can
+	// be rsa-sha2-256 or rsa-sha2-512 for the algorithm
+	// ssh-rsa-cert-v01@openssh.com.
+	//
+	// With gpg-agent < 2.2.6 the algorithm can be rsa-sha2-256 or rsa-sha2-512
+	// for signature format ssh-rsa.
+	if isRSA(algo) && isRSA(sigFormat) {
+		return true
+	}
+	// Standard case: the underlying algorithm must match the signature format.
+	return underlyingAlgo(algo) == sigFormat
+}
+
+// ServerAuthError represents server authentication errors and is
+// sometimes returned by NewServerConn. It appends any authentication
+// errors that may occur, and is returned if all of the authentication
+// methods provided by the user failed to authenticate.
+type ServerAuthError struct {
+	// Errors contains authentication errors returned by the authentication
+	// callback methods. The first entry is typically ErrNoAuth.
+	Errors []error
+}
+
+func (l ServerAuthError) Error() string {
+	var errs []string
+	for _, err := range l.Errors {
+		errs = append(errs, err.Error())
+	}
+	return "[" + strings.Join(errs, ", ") + "]"
+}
+
+// ServerAuthCallbacks defines server-side authentication callbacks.
+type ServerAuthCallbacks struct {
+	// PasswordCallback behaves like [ServerConfig.PasswordCallback].
+	PasswordCallback func(conn ConnMetadata, password []byte) (*Permissions, error)
+
+	// PublicKeyCallback behaves like [ServerConfig.PublicKeyCallback].
+	PublicKeyCallback func(conn ConnMetadata, key PublicKey) (*Permissions, error)
+
+	// KeyboardInteractiveCallback behaves like [ServerConfig.KeyboardInteractiveCallback].
+	KeyboardInteractiveCallback func(conn ConnMetadata, client KeyboardInteractiveChallenge) (*Permissions, error)
+
+	// GSSAPIWithMICConfig behaves like [ServerConfig.GSSAPIWithMICConfig].
+	GSSAPIWithMICConfig *GSSAPIWithMICConfig
+}
+
+// PartialSuccessError can be returned by any of the [ServerConfig]
+// authentication callbacks to indicate to the client that authentication has
+// partially succeeded, but further steps are required.
+type PartialSuccessError struct {
+	// Next defines the authentication callbacks to apply to further steps. The
+	// available methods communicated to the client are based on the non-nil
+	// ServerAuthCallbacks fields.
+	Next ServerAuthCallbacks
+}
+
+func (p *PartialSuccessError) Error() string {
+	return "ssh: authenticated with partial success"
+}
+
+// ErrNoAuth is the error value returned if no
+// authentication method has been passed yet. This happens as a normal
+// part of the authentication loop, since the client first tries
+// 'none' authentication to discover available methods.
+// It is returned in ServerAuthError.Errors from NewServerConn.
+var ErrNoAuth = errors.New("ssh: no auth passed yet")
+
+func (s *connection) serverAuthenticate(config *ServerConfig) (*Permissions, error) {
+	sessionID := s.transport.getSessionID()
+	var cache pubKeyCache
+	var perms *Permissions
+
+	authFailures := 0
+	noneAuthCount := 0
+	var authErrs []error
+	var displayedBanner bool
+	partialSuccessReturned := false
+	// Set the initial authentication callbacks from the config. They can be
+	// changed if a PartialSuccessError is returned.
+	authConfig := ServerAuthCallbacks{
+		PasswordCallback:            config.PasswordCallback,
+		PublicKeyCallback:           config.PublicKeyCallback,
+		KeyboardInteractiveCallback: config.KeyboardInteractiveCallback,
+		GSSAPIWithMICConfig:         config.GSSAPIWithMICConfig,
+	}
+
+userAuthLoop:
+	for {
+		if authFailures >= config.MaxAuthTries && config.MaxAuthTries > 0 {
+			discMsg := &disconnectMsg{
+				Reason:  2,
+				Message: "too many authentication failures",
+			}
+
+			if err := s.transport.writePacket(Marshal(discMsg)); err != nil {
+				return nil, err
+			}
+
+			return nil, discMsg
+		}
+
+		var userAuthReq userAuthRequestMsg
+		if packet, err := s.transport.readPacket(); err != nil {
+			if err == io.EOF {
+				return nil, &ServerAuthError{Errors: authErrs}
+			}
+			return nil, err
+		} else if err = Unmarshal(packet, &userAuthReq); err != nil {
+			return nil, err
+		}
+
+		if userAuthReq.Service != serviceSSH {
+			return nil, errors.New("ssh: client attempted to negotiate for unknown service: " + userAuthReq.Service)
+		}
+
+		if s.user != userAuthReq.User && partialSuccessReturned {
+			return nil, fmt.Errorf("ssh: client changed the user after a partial success authentication, previous user %q, current user %q",
+				s.user, userAuthReq.User)
+		}
+
+		s.user = userAuthReq.User
+
+		if !displayedBanner && config.BannerCallback != nil {
+			displayedBanner = true
+			msg := config.BannerCallback(s)
+			if msg != "" {
+				bannerMsg := &userAuthBannerMsg{
+					Message: msg,
+				}
+				if err := s.transport.writePacket(Marshal(bannerMsg)); err != nil {
+					return nil, err
+				}
+			}
+		}
+
+		perms = nil
+		authErr := ErrNoAuth
+
+		switch userAuthReq.Method {
+		case "none":
+			noneAuthCount++
+			// We don't allow none authentication after a partial success
+			// response.
+			if config.NoClientAuth && !partialSuccessReturned {
+				if config.NoClientAuthCallback != nil {
+					perms, authErr = config.NoClientAuthCallback(s)
+				} else {
+					authErr = nil
+				}
+			}
+		case "password":
+			if authConfig.PasswordCallback == nil {
+				authErr = errors.New("ssh: password auth not configured")
+				break
+			}
+			payload := userAuthReq.Payload
+			if len(payload) < 1 || payload[0] != 0 {
+				return nil, parseError(msgUserAuthRequest)
+			}
+			payload = payload[1:]
+			password, payload, ok := parseString(payload)
+			if !ok || len(payload) > 0 {
+				return nil, parseError(msgUserAuthRequest)
+			}
+
+			perms, authErr = authConfig.PasswordCallback(s, password)
+		case "keyboard-interactive":
+			if authConfig.KeyboardInteractiveCallback == nil {
+				authErr = errors.New("ssh: keyboard-interactive auth not configured")
+				break
+			}
+
+			prompter := &sshClientKeyboardInteractive{s}
+			perms, authErr = authConfig.KeyboardInteractiveCallback(s, prompter.Challenge)
+		case "publickey":
+			if authConfig.PublicKeyCallback == nil {
+				authErr = errors.New("ssh: publickey auth not configured")
+				break
+			}
+			payload := userAuthReq.Payload
+			if len(payload) < 1 {
+				return nil, parseError(msgUserAuthRequest)
+			}
+			isQuery := payload[0] == 0
+			payload = payload[1:]
+			algoBytes, payload, ok := parseString(payload)
+			if !ok {
+				return nil, parseError(msgUserAuthRequest)
+			}
+			algo := string(algoBytes)
+			if !contains(config.PublicKeyAuthAlgorithms, underlyingAlgo(algo)) {
+				authErr = fmt.Errorf("ssh: algorithm %q not accepted", algo)
+				break
+			}
+
+			pubKeyData, payload, ok := parseString(payload)
+			if !ok {
+				return nil, parseError(msgUserAuthRequest)
+			}
+
+			pubKey, err := ParsePublicKey(pubKeyData)
+			if err != nil {
+				return nil, err
+			}
+
+			candidate, ok := cache.get(s.user, pubKeyData)
+			if !ok {
+				candidate.user = s.user
+				candidate.pubKeyData = pubKeyData
+				candidate.perms, candidate.result = authConfig.PublicKeyCallback(s, pubKey)
+				_, isPartialSuccessError := candidate.result.(*PartialSuccessError)
+
+				if (candidate.result == nil || isPartialSuccessError) &&
+					candidate.perms != nil &&
+					candidate.perms.CriticalOptions != nil &&
+					candidate.perms.CriticalOptions[sourceAddressCriticalOption] != "" {
+					if err := checkSourceAddress(
+						s.RemoteAddr(),
+						candidate.perms.CriticalOptions[sourceAddressCriticalOption]); err != nil {
+						candidate.result = err
+					}
+				}
+				cache.add(candidate)
+			}
+
+			if isQuery {
+				// The client can query if the given public key
+				// would be okay.
+
+				if len(payload) > 0 {
+					return nil, parseError(msgUserAuthRequest)
+				}
+				_, isPartialSuccessError := candidate.result.(*PartialSuccessError)
+				if candidate.result == nil || isPartialSuccessError {
+					okMsg := userAuthPubKeyOkMsg{
+						Algo:   algo,
+						PubKey: pubKeyData,
+					}
+					if err = s.transport.writePacket(Marshal(&okMsg)); err != nil {
+						return nil, err
+					}
+					continue userAuthLoop
+				}
+				authErr = candidate.result
+			} else {
+				sig, payload, ok := parseSignature(payload)
+				if !ok || len(payload) > 0 {
+					return nil, parseError(msgUserAuthRequest)
+				}
+				// Ensure the declared public key algo is compatible with the
+				// decoded one. This check will ensure we don't accept e.g.
+				// ssh-rsa-cert-v01@openssh.com algorithm with ssh-rsa public
+				// key type. The algorithm and public key type must be
+				// consistent: both must be certificate algorithms, or neither.
+				if !contains(algorithmsForKeyFormat(pubKey.Type()), algo) {
+					authErr = fmt.Errorf("ssh: public key type %q not compatible with selected algorithm %q",
+						pubKey.Type(), algo)
+					break
+				}
+				// Ensure the public key algo and signature algo
+				// are supported.  Compare the private key
+				// algorithm name that corresponds to algo with
+				// sig.Format.  This is usually the same, but
+				// for certs, the names differ.
+				if !contains(config.PublicKeyAuthAlgorithms, sig.Format) {
+					authErr = fmt.Errorf("ssh: algorithm %q not accepted", sig.Format)
+					break
+				}
+				if !isAlgoCompatible(algo, sig.Format) {
+					authErr = fmt.Errorf("ssh: signature %q not compatible with selected algorithm %q", sig.Format, algo)
+					break
+				}
+
+				signedData := buildDataSignedForAuth(sessionID, userAuthReq, algo, pubKeyData)
+
+				if err := pubKey.Verify(signedData, sig); err != nil {
+					return nil, err
+				}
+
+				authErr = candidate.result
+				perms = candidate.perms
+			}
+		case "gssapi-with-mic":
+			if authConfig.GSSAPIWithMICConfig == nil {
+				authErr = errors.New("ssh: gssapi-with-mic auth not configured")
+				break
+			}
+			gssapiConfig := authConfig.GSSAPIWithMICConfig
+			userAuthRequestGSSAPI, err := parseGSSAPIPayload(userAuthReq.Payload)
+			if err != nil {
+				return nil, parseError(msgUserAuthRequest)
+			}
+			// OpenSSH supports Kerberos V5 mechanism only for GSS-API authentication.
+			if userAuthRequestGSSAPI.N == 0 {
+				authErr = fmt.Errorf("ssh: Mechanism negotiation is not supported")
+				break
+			}
+			var i uint32
+			present := false
+			for i = 0; i < userAuthRequestGSSAPI.N; i++ {
+				if userAuthRequestGSSAPI.OIDS[i].Equal(krb5Mesh) {
+					present = true
+					break
+				}
+			}
+			if !present {
+				authErr = fmt.Errorf("ssh: GSSAPI authentication must use the Kerberos V5 mechanism")
+				break
+			}
+			// Initial server response, see RFC 4462 section 3.3.
+			if err := s.transport.writePacket(Marshal(&userAuthGSSAPIResponse{
+				SupportMech: krb5OID,
+			})); err != nil {
+				return nil, err
+			}
+			// Exchange token, see RFC 4462 section 3.4.
+			packet, err := s.transport.readPacket()
+			if err != nil {
+				return nil, err
+			}
+			userAuthGSSAPITokenReq := &userAuthGSSAPIToken{}
+			if err := Unmarshal(packet, userAuthGSSAPITokenReq); err != nil {
+				return nil, err
+			}
+			authErr, perms, err = gssExchangeToken(gssapiConfig, userAuthGSSAPITokenReq.Token, s, sessionID,
+				userAuthReq)
+			if err != nil {
+				return nil, err
+			}
+		default:
+			authErr = fmt.Errorf("ssh: unknown method %q", userAuthReq.Method)
+		}
+
+		authErrs = append(authErrs, authErr)
+
+		if config.AuthLogCallback != nil {
+			config.AuthLogCallback(s, userAuthReq.Method, authErr)
+		}
+
+		if authErr == nil {
+			break userAuthLoop
+		}
+
+		var failureMsg userAuthFailureMsg
+
+		if partialSuccess, ok := authErr.(*PartialSuccessError); ok {
+			// After a partial success error we don't allow changing the user
+			// name and execute the NoClientAuthCallback.
+			partialSuccessReturned = true
+
+			// In case a partial success is returned, the server may send
+			// a new set of authentication methods.
+			authConfig = partialSuccess.Next
+
+			// Reset pubkey cache, as the new PublicKeyCallback might
+			// accept a different set of public keys.
+			cache = pubKeyCache{}
+
+			// Send back a partial success message to the user.
+			failureMsg.PartialSuccess = true
+		} else {
+			// Allow initial attempt of 'none' without penalty.
+			if authFailures > 0 || userAuthReq.Method != "none" || noneAuthCount != 1 {
+				authFailures++
+			}
+			if config.MaxAuthTries > 0 && authFailures >= config.MaxAuthTries {
+				// If we have hit the max attempts, don't bother sending the
+				// final SSH_MSG_USERAUTH_FAILURE message, since there are
+				// no more authentication methods which can be attempted,
+				// and this message may cause the client to re-attempt
+				// authentication while we send the disconnect message.
+				// Continue, and trigger the disconnect at the start of
+				// the loop.
+				//
+				// The SSH specification is somewhat confusing about this,
+				// RFC 4252 Section 5.1 requires each authentication failure
+				// be responded to with a respective SSH_MSG_USERAUTH_FAILURE
+				// message, but Section 4 says the server should disconnect
+				// after some number of attempts, but it isn't explicit which
+				// message should take precedence (i.e. should there be a failure
+				// message than a disconnect message, or if we are going to
+				// disconnect, should we only send that message.)
+				//
+				// Either way, OpenSSH disconnects immediately after the last
+				// failed authentication attempt, and given they are typically
+				// considered the golden implementation it seems reasonable
+				// to match that behavior.
+				continue
+			}
+		}
+
+		if authConfig.PasswordCallback != nil {
+			failureMsg.Methods = append(failureMsg.Methods, "password")
+		}
+		if authConfig.PublicKeyCallback != nil {
+			failureMsg.Methods = append(failureMsg.Methods, "publickey")
+		}
+		if authConfig.KeyboardInteractiveCallback != nil {
+			failureMsg.Methods = append(failureMsg.Methods, "keyboard-interactive")
+		}
+		if authConfig.GSSAPIWithMICConfig != nil && authConfig.GSSAPIWithMICConfig.Server != nil &&
+			authConfig.GSSAPIWithMICConfig.AllowLogin != nil {
+			failureMsg.Methods = append(failureMsg.Methods, "gssapi-with-mic")
+		}
+
+		if len(failureMsg.Methods) == 0 {
+			return nil, errors.New("ssh: no authentication methods available")
+		}
+
+		if err := s.transport.writePacket(Marshal(&failureMsg)); err != nil {
+			return nil, err
+		}
+	}
+
+	if err := s.transport.writePacket([]byte{msgUserAuthSuccess}); err != nil {
+		return nil, err
+	}
+	return perms, nil
+}
+
+// sshClientKeyboardInteractive implements a ClientKeyboardInteractive by
+// asking the client on the other side of a ServerConn.
+type sshClientKeyboardInteractive struct {
+	*connection
+}
+
+func (c *sshClientKeyboardInteractive) Challenge(name, instruction string, questions []string, echos []bool) (answers []string, err error) {
+	if len(questions) != len(echos) {
+		return nil, errors.New("ssh: echos and questions must have equal length")
+	}
+
+	var prompts []byte
+	for i := range questions {
+		prompts = appendString(prompts, questions[i])
+		prompts = appendBool(prompts, echos[i])
+	}
+
+	if err := c.transport.writePacket(Marshal(&userAuthInfoRequestMsg{
+		Name:        name,
+		Instruction: instruction,
+		NumPrompts:  uint32(len(questions)),
+		Prompts:     prompts,
+	})); err != nil {
+		return nil, err
+	}
+
+	packet, err := c.transport.readPacket()
+	if err != nil {
+		return nil, err
+	}
+	if packet[0] != msgUserAuthInfoResponse {
+		return nil, unexpectedMessageError(msgUserAuthInfoResponse, packet[0])
+	}
+	packet = packet[1:]
+
+	n, packet, ok := parseUint32(packet)
+	if !ok || int(n) != len(questions) {
+		return nil, parseError(msgUserAuthInfoResponse)
+	}
+
+	for i := uint32(0); i < n; i++ {
+		ans, rest, ok := parseString(packet)
+		if !ok {
+			return nil, parseError(msgUserAuthInfoResponse)
+		}
+
+		answers = append(answers, string(ans))
+		packet = rest
+	}
+	if len(packet) != 0 {
+		return nil, errors.New("ssh: junk at end of message")
+	}
+
+	return answers, nil
+}
diff --git a/vendor/golang.org/x/crypto/ssh/session.go b/vendor/golang.org/x/crypto/ssh/session.go
new file mode 100644
index 000000000..acef62259
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/session.go
@@ -0,0 +1,647 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+// Session implements an interactive session described in
+// "RFC 4254, section 6".
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"sync"
+)
+
+type Signal string
+
+// POSIX signals as listed in RFC 4254 Section 6.10.
+const (
+	SIGABRT Signal = "ABRT"
+	SIGALRM Signal = "ALRM"
+	SIGFPE  Signal = "FPE"
+	SIGHUP  Signal = "HUP"
+	SIGILL  Signal = "ILL"
+	SIGINT  Signal = "INT"
+	SIGKILL Signal = "KILL"
+	SIGPIPE Signal = "PIPE"
+	SIGQUIT Signal = "QUIT"
+	SIGSEGV Signal = "SEGV"
+	SIGTERM Signal = "TERM"
+	SIGUSR1 Signal = "USR1"
+	SIGUSR2 Signal = "USR2"
+)
+
+var signals = map[Signal]int{
+	SIGABRT: 6,
+	SIGALRM: 14,
+	SIGFPE:  8,
+	SIGHUP:  1,
+	SIGILL:  4,
+	SIGINT:  2,
+	SIGKILL: 9,
+	SIGPIPE: 13,
+	SIGQUIT: 3,
+	SIGSEGV: 11,
+	SIGTERM: 15,
+}
+
+type TerminalModes map[uint8]uint32
+
+// POSIX terminal mode flags as listed in RFC 4254 Section 8.
+const (
+	tty_OP_END    = 0
+	VINTR         = 1
+	VQUIT         = 2
+	VERASE        = 3
+	VKILL         = 4
+	VEOF          = 5
+	VEOL          = 6
+	VEOL2         = 7
+	VSTART        = 8
+	VSTOP         = 9
+	VSUSP         = 10
+	VDSUSP        = 11
+	VREPRINT      = 12
+	VWERASE       = 13
+	VLNEXT        = 14
+	VFLUSH        = 15
+	VSWTCH        = 16
+	VSTATUS       = 17
+	VDISCARD      = 18
+	IGNPAR        = 30
+	PARMRK        = 31
+	INPCK         = 32
+	ISTRIP        = 33
+	INLCR         = 34
+	IGNCR         = 35
+	ICRNL         = 36
+	IUCLC         = 37
+	IXON          = 38
+	IXANY         = 39
+	IXOFF         = 40
+	IMAXBEL       = 41
+	IUTF8         = 42 // RFC 8160
+	ISIG          = 50
+	ICANON        = 51
+	XCASE         = 52
+	ECHO          = 53
+	ECHOE         = 54
+	ECHOK         = 55
+	ECHONL        = 56
+	NOFLSH        = 57
+	TOSTOP        = 58
+	IEXTEN        = 59
+	ECHOCTL       = 60
+	ECHOKE        = 61
+	PENDIN        = 62
+	OPOST         = 70
+	OLCUC         = 71
+	ONLCR         = 72
+	OCRNL         = 73
+	ONOCR         = 74
+	ONLRET        = 75
+	CS7           = 90
+	CS8           = 91
+	PARENB        = 92
+	PARODD        = 93
+	TTY_OP_ISPEED = 128
+	TTY_OP_OSPEED = 129
+)
+
+// A Session represents a connection to a remote command or shell.
+type Session struct {
+	// Stdin specifies the remote process's standard input.
+	// If Stdin is nil, the remote process reads from an empty
+	// bytes.Buffer.
+	Stdin io.Reader
+
+	// Stdout and Stderr specify the remote process's standard
+	// output and error.
+	//
+	// If either is nil, Run connects the corresponding file
+	// descriptor to an instance of io.Discard. There is a
+	// fixed amount of buffering that is shared for the two streams.
+	// If either blocks it may eventually cause the remote
+	// command to block.
+	Stdout io.Writer
+	Stderr io.Writer
+
+	ch        Channel // the channel backing this session
+	started   bool    // true once Start, Run or Shell is invoked.
+	copyFuncs []func() error
+	errors    chan error // one send per copyFunc
+
+	// true if pipe method is active
+	stdinpipe, stdoutpipe, stderrpipe bool
+
+	// stdinPipeWriter is non-nil if StdinPipe has not been called
+	// and Stdin was specified by the user; it is the write end of
+	// a pipe connecting Session.Stdin to the stdin channel.
+	stdinPipeWriter io.WriteCloser
+
+	exitStatus chan error
+}
+
+// SendRequest sends an out-of-band channel request on the SSH channel
+// underlying the session.
+func (s *Session) SendRequest(name string, wantReply bool, payload []byte) (bool, error) {
+	return s.ch.SendRequest(name, wantReply, payload)
+}
+
+func (s *Session) Close() error {
+	return s.ch.Close()
+}
+
+// RFC 4254 Section 6.4.
+type setenvRequest struct {
+	Name  string
+	Value string
+}
+
+// Setenv sets an environment variable that will be applied to any
+// command executed by Shell or Run.
+func (s *Session) Setenv(name, value string) error {
+	msg := setenvRequest{
+		Name:  name,
+		Value: value,
+	}
+	ok, err := s.ch.SendRequest("env", true, Marshal(&msg))
+	if err == nil && !ok {
+		err = errors.New("ssh: setenv failed")
+	}
+	return err
+}
+
+// RFC 4254 Section 6.2.
+type ptyRequestMsg struct {
+	Term     string
+	Columns  uint32
+	Rows     uint32
+	Width    uint32
+	Height   uint32
+	Modelist string
+}
+
+// RequestPty requests the association of a pty with the session on the remote host.
+func (s *Session) RequestPty(term string, h, w int, termmodes TerminalModes) error {
+	var tm []byte
+	for k, v := range termmodes {
+		kv := struct {
+			Key byte
+			Val uint32
+		}{k, v}
+
+		tm = append(tm, Marshal(&kv)...)
+	}
+	tm = append(tm, tty_OP_END)
+	req := ptyRequestMsg{
+		Term:     term,
+		Columns:  uint32(w),
+		Rows:     uint32(h),
+		Width:    uint32(w * 8),
+		Height:   uint32(h * 8),
+		Modelist: string(tm),
+	}
+	ok, err := s.ch.SendRequest("pty-req", true, Marshal(&req))
+	if err == nil && !ok {
+		err = errors.New("ssh: pty-req failed")
+	}
+	return err
+}
+
+// RFC 4254 Section 6.5.
+type subsystemRequestMsg struct {
+	Subsystem string
+}
+
+// RequestSubsystem requests the association of a subsystem with the session on the remote host.
+// A subsystem is a predefined command that runs in the background when the ssh session is initiated
+func (s *Session) RequestSubsystem(subsystem string) error {
+	msg := subsystemRequestMsg{
+		Subsystem: subsystem,
+	}
+	ok, err := s.ch.SendRequest("subsystem", true, Marshal(&msg))
+	if err == nil && !ok {
+		err = errors.New("ssh: subsystem request failed")
+	}
+	return err
+}
+
+// RFC 4254 Section 6.7.
+type ptyWindowChangeMsg struct {
+	Columns uint32
+	Rows    uint32
+	Width   uint32
+	Height  uint32
+}
+
+// WindowChange informs the remote host about a terminal window dimension change to h rows and w columns.
+func (s *Session) WindowChange(h, w int) error {
+	req := ptyWindowChangeMsg{
+		Columns: uint32(w),
+		Rows:    uint32(h),
+		Width:   uint32(w * 8),
+		Height:  uint32(h * 8),
+	}
+	_, err := s.ch.SendRequest("window-change", false, Marshal(&req))
+	return err
+}
+
+// RFC 4254 Section 6.9.
+type signalMsg struct {
+	Signal string
+}
+
+// Signal sends the given signal to the remote process.
+// sig is one of the SIG* constants.
+func (s *Session) Signal(sig Signal) error {
+	msg := signalMsg{
+		Signal: string(sig),
+	}
+
+	_, err := s.ch.SendRequest("signal", false, Marshal(&msg))
+	return err
+}
+
+// RFC 4254 Section 6.5.
+type execMsg struct {
+	Command string
+}
+
+// Start runs cmd on the remote host. Typically, the remote
+// server passes cmd to the shell for interpretation.
+// A Session only accepts one call to Run, Start or Shell.
+func (s *Session) Start(cmd string) error {
+	if s.started {
+		return errors.New("ssh: session already started")
+	}
+	req := execMsg{
+		Command: cmd,
+	}
+
+	ok, err := s.ch.SendRequest("exec", true, Marshal(&req))
+	if err == nil && !ok {
+		err = fmt.Errorf("ssh: command %v failed", cmd)
+	}
+	if err != nil {
+		return err
+	}
+	return s.start()
+}
+
+// Run runs cmd on the remote host. Typically, the remote
+// server passes cmd to the shell for interpretation.
+// A Session only accepts one call to Run, Start, Shell, Output,
+// or CombinedOutput.
+//
+// The returned error is nil if the command runs, has no problems
+// copying stdin, stdout, and stderr, and exits with a zero exit
+// status.
+//
+// If the remote server does not send an exit status, an error of type
+// *ExitMissingError is returned. If the command completes
+// unsuccessfully or is interrupted by a signal, the error is of type
+// *ExitError. Other error types may be returned for I/O problems.
+func (s *Session) Run(cmd string) error {
+	err := s.Start(cmd)
+	if err != nil {
+		return err
+	}
+	return s.Wait()
+}
+
+// Output runs cmd on the remote host and returns its standard output.
+func (s *Session) Output(cmd string) ([]byte, error) {
+	if s.Stdout != nil {
+		return nil, errors.New("ssh: Stdout already set")
+	}
+	var b bytes.Buffer
+	s.Stdout = &b
+	err := s.Run(cmd)
+	return b.Bytes(), err
+}
+
+type singleWriter struct {
+	b  bytes.Buffer
+	mu sync.Mutex
+}
+
+func (w *singleWriter) Write(p []byte) (int, error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	return w.b.Write(p)
+}
+
+// CombinedOutput runs cmd on the remote host and returns its combined
+// standard output and standard error.
+func (s *Session) CombinedOutput(cmd string) ([]byte, error) {
+	if s.Stdout != nil {
+		return nil, errors.New("ssh: Stdout already set")
+	}
+	if s.Stderr != nil {
+		return nil, errors.New("ssh: Stderr already set")
+	}
+	var b singleWriter
+	s.Stdout = &b
+	s.Stderr = &b
+	err := s.Run(cmd)
+	return b.b.Bytes(), err
+}
+
+// Shell starts a login shell on the remote host. A Session only
+// accepts one call to Run, Start, Shell, Output, or CombinedOutput.
+func (s *Session) Shell() error {
+	if s.started {
+		return errors.New("ssh: session already started")
+	}
+
+	ok, err := s.ch.SendRequest("shell", true, nil)
+	if err == nil && !ok {
+		return errors.New("ssh: could not start shell")
+	}
+	if err != nil {
+		return err
+	}
+	return s.start()
+}
+
+func (s *Session) start() error {
+	s.started = true
+
+	type F func(*Session)
+	for _, setupFd := range []F{(*Session).stdin, (*Session).stdout, (*Session).stderr} {
+		setupFd(s)
+	}
+
+	s.errors = make(chan error, len(s.copyFuncs))
+	for _, fn := range s.copyFuncs {
+		go func(fn func() error) {
+			s.errors <- fn()
+		}(fn)
+	}
+	return nil
+}
+
+// Wait waits for the remote command to exit.
+//
+// The returned error is nil if the command runs, has no problems
+// copying stdin, stdout, and stderr, and exits with a zero exit
+// status.
+//
+// If the remote server does not send an exit status, an error of type
+// *ExitMissingError is returned. If the command completes
+// unsuccessfully or is interrupted by a signal, the error is of type
+// *ExitError. Other error types may be returned for I/O problems.
+func (s *Session) Wait() error {
+	if !s.started {
+		return errors.New("ssh: session not started")
+	}
+	waitErr := <-s.exitStatus
+
+	if s.stdinPipeWriter != nil {
+		s.stdinPipeWriter.Close()
+	}
+	var copyError error
+	for range s.copyFuncs {
+		if err := <-s.errors; err != nil && copyError == nil {
+			copyError = err
+		}
+	}
+	if waitErr != nil {
+		return waitErr
+	}
+	return copyError
+}
+
+func (s *Session) wait(reqs <-chan *Request) error {
+	wm := Waitmsg{status: -1}
+	// Wait for msg channel to be closed before returning.
+	for msg := range reqs {
+		switch msg.Type {
+		case "exit-status":
+			wm.status = int(binary.BigEndian.Uint32(msg.Payload))
+		case "exit-signal":
+			var sigval struct {
+				Signal     string
+				CoreDumped bool
+				Error      string
+				Lang       string
+			}
+			if err := Unmarshal(msg.Payload, &sigval); err != nil {
+				return err
+			}
+
+			// Must sanitize strings?
+			wm.signal = sigval.Signal
+			wm.msg = sigval.Error
+			wm.lang = sigval.Lang
+		default:
+			// This handles keepalives and matches
+			// OpenSSH's behaviour.
+			if msg.WantReply {
+				msg.Reply(false, nil)
+			}
+		}
+	}
+	if wm.status == 0 {
+		return nil
+	}
+	if wm.status == -1 {
+		// exit-status was never sent from server
+		if wm.signal == "" {
+			// signal was not sent either.  RFC 4254
+			// section 6.10 recommends against this
+			// behavior, but it is allowed, so we let
+			// clients handle it.
+			return &ExitMissingError{}
+		}
+		wm.status = 128
+		if _, ok := signals[Signal(wm.signal)]; ok {
+			wm.status += signals[Signal(wm.signal)]
+		}
+	}
+
+	return &ExitError{wm}
+}
+
+// ExitMissingError is returned if a session is torn down cleanly, but
+// the server sends no confirmation of the exit status.
+type ExitMissingError struct{}
+
+func (e *ExitMissingError) Error() string {
+	return "wait: remote command exited without exit status or exit signal"
+}
+
+func (s *Session) stdin() {
+	if s.stdinpipe {
+		return
+	}
+	var stdin io.Reader
+	if s.Stdin == nil {
+		stdin = new(bytes.Buffer)
+	} else {
+		r, w := io.Pipe()
+		go func() {
+			_, err := io.Copy(w, s.Stdin)
+			w.CloseWithError(err)
+		}()
+		stdin, s.stdinPipeWriter = r, w
+	}
+	s.copyFuncs = append(s.copyFuncs, func() error {
+		_, err := io.Copy(s.ch, stdin)
+		if err1 := s.ch.CloseWrite(); err == nil && err1 != io.EOF {
+			err = err1
+		}
+		return err
+	})
+}
+
+func (s *Session) stdout() {
+	if s.stdoutpipe {
+		return
+	}
+	if s.Stdout == nil {
+		s.Stdout = io.Discard
+	}
+	s.copyFuncs = append(s.copyFuncs, func() error {
+		_, err := io.Copy(s.Stdout, s.ch)
+		return err
+	})
+}
+
+func (s *Session) stderr() {
+	if s.stderrpipe {
+		return
+	}
+	if s.Stderr == nil {
+		s.Stderr = io.Discard
+	}
+	s.copyFuncs = append(s.copyFuncs, func() error {
+		_, err := io.Copy(s.Stderr, s.ch.Stderr())
+		return err
+	})
+}
+
+// sessionStdin reroutes Close to CloseWrite.
+type sessionStdin struct {
+	io.Writer
+	ch Channel
+}
+
+func (s *sessionStdin) Close() error {
+	return s.ch.CloseWrite()
+}
+
+// StdinPipe returns a pipe that will be connected to the
+// remote command's standard input when the command starts.
+func (s *Session) StdinPipe() (io.WriteCloser, error) {
+	if s.Stdin != nil {
+		return nil, errors.New("ssh: Stdin already set")
+	}
+	if s.started {
+		return nil, errors.New("ssh: StdinPipe after process started")
+	}
+	s.stdinpipe = true
+	return &sessionStdin{s.ch, s.ch}, nil
+}
+
+// StdoutPipe returns a pipe that will be connected to the
+// remote command's standard output when the command starts.
+// There is a fixed amount of buffering that is shared between
+// stdout and stderr streams. If the StdoutPipe reader is
+// not serviced fast enough it may eventually cause the
+// remote command to block.
+func (s *Session) StdoutPipe() (io.Reader, error) {
+	if s.Stdout != nil {
+		return nil, errors.New("ssh: Stdout already set")
+	}
+	if s.started {
+		return nil, errors.New("ssh: StdoutPipe after process started")
+	}
+	s.stdoutpipe = true
+	return s.ch, nil
+}
+
+// StderrPipe returns a pipe that will be connected to the
+// remote command's standard error when the command starts.
+// There is a fixed amount of buffering that is shared between
+// stdout and stderr streams. If the StderrPipe reader is
+// not serviced fast enough it may eventually cause the
+// remote command to block.
+func (s *Session) StderrPipe() (io.Reader, error) {
+	if s.Stderr != nil {
+		return nil, errors.New("ssh: Stderr already set")
+	}
+	if s.started {
+		return nil, errors.New("ssh: StderrPipe after process started")
+	}
+	s.stderrpipe = true
+	return s.ch.Stderr(), nil
+}
+
+// newSession returns a new interactive session on the remote host.
+func newSession(ch Channel, reqs <-chan *Request) (*Session, error) {
+	s := &Session{
+		ch: ch,
+	}
+	s.exitStatus = make(chan error, 1)
+	go func() {
+		s.exitStatus <- s.wait(reqs)
+	}()
+
+	return s, nil
+}
+
+// An ExitError reports unsuccessful completion of a remote command.
+type ExitError struct {
+	Waitmsg
+}
+
+func (e *ExitError) Error() string {
+	return e.Waitmsg.String()
+}
+
+// Waitmsg stores the information about an exited remote command
+// as reported by Wait.
+type Waitmsg struct {
+	status int
+	signal string
+	msg    string
+	lang   string
+}
+
+// ExitStatus returns the exit status of the remote command.
+func (w Waitmsg) ExitStatus() int {
+	return w.status
+}
+
+// Signal returns the exit signal of the remote command if
+// it was terminated violently.
+func (w Waitmsg) Signal() string {
+	return w.signal
+}
+
+// Msg returns the exit message given by the remote command
+func (w Waitmsg) Msg() string {
+	return w.msg
+}
+
+// Lang returns the language tag. See RFC 3066
+func (w Waitmsg) Lang() string {
+	return w.lang
+}
+
+func (w Waitmsg) String() string {
+	str := fmt.Sprintf("Process exited with status %v", w.status)
+	if w.signal != "" {
+		str += fmt.Sprintf(" from signal %v", w.signal)
+	}
+	if w.msg != "" {
+		str += fmt.Sprintf(". Reason was: %v", w.msg)
+	}
+	return str
+}
diff --git a/vendor/golang.org/x/crypto/ssh/ssh_gss.go b/vendor/golang.org/x/crypto/ssh/ssh_gss.go
new file mode 100644
index 000000000..24bd7c8e8
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/ssh_gss.go
@@ -0,0 +1,139 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"encoding/asn1"
+	"errors"
+)
+
+var krb5OID []byte
+
+func init() {
+	krb5OID, _ = asn1.Marshal(krb5Mesh)
+}
+
+// GSSAPIClient provides the API to plug-in GSSAPI authentication for client logins.
+type GSSAPIClient interface {
+	// InitSecContext initiates the establishment of a security context for GSS-API between the
+	// ssh client and ssh server. Initially the token parameter should be specified as nil.
+	// The routine may return a outputToken which should be transferred to
+	// the ssh server, where the ssh server will present it to
+	// AcceptSecContext. If no token need be sent, InitSecContext will indicate this by setting
+	// needContinue to false. To complete the context
+	// establishment, one or more reply tokens may be required from the ssh
+	// server;if so, InitSecContext will return a needContinue which is true.
+	// In this case, InitSecContext should be called again when the
+	// reply token is received from the ssh server, passing the reply
+	// token to InitSecContext via the token parameters.
+	// See RFC 2743 section 2.2.1 and RFC 4462 section 3.4.
+	InitSecContext(target string, token []byte, isGSSDelegCreds bool) (outputToken []byte, needContinue bool, err error)
+	// GetMIC generates a cryptographic MIC for the SSH2 message, and places
+	// the MIC in a token for transfer to the ssh server.
+	// The contents of the MIC field are obtained by calling GSS_GetMIC()
+	// over the following, using the GSS-API context that was just
+	// established:
+	//  string    session identifier
+	//  byte      SSH_MSG_USERAUTH_REQUEST
+	//  string    user name
+	//  string    service
+	//  string    "gssapi-with-mic"
+	// See RFC 2743 section 2.3.1 and RFC 4462 3.5.
+	GetMIC(micFiled []byte) ([]byte, error)
+	// Whenever possible, it should be possible for
+	// DeleteSecContext() calls to be successfully processed even
+	// if other calls cannot succeed, thereby enabling context-related
+	// resources to be released.
+	// In addition to deleting established security contexts,
+	// gss_delete_sec_context must also be able to delete "half-built"
+	// security contexts resulting from an incomplete sequence of
+	// InitSecContext()/AcceptSecContext() calls.
+	// See RFC 2743 section 2.2.3.
+	DeleteSecContext() error
+}
+
+// GSSAPIServer provides the API to plug in GSSAPI authentication for server logins.
+type GSSAPIServer interface {
+	// AcceptSecContext allows a remotely initiated security context between the application
+	// and a remote peer to be established by the ssh client. The routine may return a
+	// outputToken which should be transferred to the ssh client,
+	// where the ssh client will present it to InitSecContext.
+	// If no token need be sent, AcceptSecContext will indicate this
+	// by setting the needContinue to false. To
+	// complete the context establishment, one or more reply tokens may be
+	// required from the ssh client. if so, AcceptSecContext
+	// will return a needContinue which is true, in which case it
+	// should be called again when the reply token is received from the ssh
+	// client, passing the token to AcceptSecContext via the
+	// token parameters.
+	// The srcName return value is the authenticated username.
+	// See RFC 2743 section 2.2.2 and RFC 4462 section 3.4.
+	AcceptSecContext(token []byte) (outputToken []byte, srcName string, needContinue bool, err error)
+	// VerifyMIC verifies that a cryptographic MIC, contained in the token parameter,
+	// fits the supplied message is received from the ssh client.
+	// See RFC 2743 section 2.3.2.
+	VerifyMIC(micField []byte, micToken []byte) error
+	// Whenever possible, it should be possible for
+	// DeleteSecContext() calls to be successfully processed even
+	// if other calls cannot succeed, thereby enabling context-related
+	// resources to be released.
+	// In addition to deleting established security contexts,
+	// gss_delete_sec_context must also be able to delete "half-built"
+	// security contexts resulting from an incomplete sequence of
+	// InitSecContext()/AcceptSecContext() calls.
+	// See RFC 2743 section 2.2.3.
+	DeleteSecContext() error
+}
+
+var (
+	// OpenSSH supports Kerberos V5 mechanism only for GSS-API authentication,
+	// so we also support the krb5 mechanism only.
+	// See RFC 1964 section 1.
+	krb5Mesh = asn1.ObjectIdentifier{1, 2, 840, 113554, 1, 2, 2}
+)
+
+// The GSS-API authentication method is initiated when the client sends an SSH_MSG_USERAUTH_REQUEST
+// See RFC 4462 section 3.2.
+type userAuthRequestGSSAPI struct {
+	N    uint32
+	OIDS []asn1.ObjectIdentifier
+}
+
+func parseGSSAPIPayload(payload []byte) (*userAuthRequestGSSAPI, error) {
+	n, rest, ok := parseUint32(payload)
+	if !ok {
+		return nil, errors.New("parse uint32 failed")
+	}
+	s := &userAuthRequestGSSAPI{
+		N:    n,
+		OIDS: make([]asn1.ObjectIdentifier, n),
+	}
+	for i := 0; i < int(n); i++ {
+		var (
+			desiredMech []byte
+			err         error
+		)
+		desiredMech, rest, ok = parseString(rest)
+		if !ok {
+			return nil, errors.New("parse string failed")
+		}
+		if rest, err = asn1.Unmarshal(desiredMech, &s.OIDS[i]); err != nil {
+			return nil, err
+		}
+
+	}
+	return s, nil
+}
+
+// See RFC 4462 section 3.6.
+func buildMIC(sessionID string, username string, service string, authMethod string) []byte {
+	out := make([]byte, 0, 0)
+	out = appendString(out, sessionID)
+	out = append(out, msgUserAuthRequest)
+	out = appendString(out, username)
+	out = appendString(out, service)
+	out = appendString(out, authMethod)
+	return out
+}
diff --git a/vendor/golang.org/x/crypto/ssh/streamlocal.go b/vendor/golang.org/x/crypto/ssh/streamlocal.go
new file mode 100644
index 000000000..b171b330b
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/streamlocal.go
@@ -0,0 +1,116 @@
+package ssh
+
+import (
+	"errors"
+	"io"
+	"net"
+)
+
+// streamLocalChannelOpenDirectMsg is a struct used for SSH_MSG_CHANNEL_OPEN message
+// with "direct-streamlocal@openssh.com" string.
+//
+// See openssh-portable/PROTOCOL, section 2.4. connection: Unix domain socket forwarding
+// https://github.com/openssh/openssh-portable/blob/master/PROTOCOL#L235
+type streamLocalChannelOpenDirectMsg struct {
+	socketPath string
+	reserved0  string
+	reserved1  uint32
+}
+
+// forwardedStreamLocalPayload is a struct used for SSH_MSG_CHANNEL_OPEN message
+// with "forwarded-streamlocal@openssh.com" string.
+type forwardedStreamLocalPayload struct {
+	SocketPath string
+	Reserved0  string
+}
+
+// streamLocalChannelForwardMsg is a struct used for SSH2_MSG_GLOBAL_REQUEST message
+// with "streamlocal-forward@openssh.com"/"cancel-streamlocal-forward@openssh.com" string.
+type streamLocalChannelForwardMsg struct {
+	socketPath string
+}
+
+// ListenUnix is similar to ListenTCP but uses a Unix domain socket.
+func (c *Client) ListenUnix(socketPath string) (net.Listener, error) {
+	c.handleForwardsOnce.Do(c.handleForwards)
+	m := streamLocalChannelForwardMsg{
+		socketPath,
+	}
+	// send message
+	ok, _, err := c.SendRequest("streamlocal-forward@openssh.com", true, Marshal(&m))
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, errors.New("ssh: streamlocal-forward@openssh.com request denied by peer")
+	}
+	ch := c.forwards.add(&net.UnixAddr{Name: socketPath, Net: "unix"})
+
+	return &unixListener{socketPath, c, ch}, nil
+}
+
+func (c *Client) dialStreamLocal(socketPath string) (Channel, error) {
+	msg := streamLocalChannelOpenDirectMsg{
+		socketPath: socketPath,
+	}
+	ch, in, err := c.OpenChannel("direct-streamlocal@openssh.com", Marshal(&msg))
+	if err != nil {
+		return nil, err
+	}
+	go DiscardRequests(in)
+	return ch, err
+}
+
+type unixListener struct {
+	socketPath string
+
+	conn *Client
+	in   <-chan forward
+}
+
+// Accept waits for and returns the next connection to the listener.
+func (l *unixListener) Accept() (net.Conn, error) {
+	s, ok := <-l.in
+	if !ok {
+		return nil, io.EOF
+	}
+	ch, incoming, err := s.newCh.Accept()
+	if err != nil {
+		return nil, err
+	}
+	go DiscardRequests(incoming)
+
+	return &chanConn{
+		Channel: ch,
+		laddr: &net.UnixAddr{
+			Name: l.socketPath,
+			Net:  "unix",
+		},
+		raddr: &net.UnixAddr{
+			Name: "@",
+			Net:  "unix",
+		},
+	}, nil
+}
+
+// Close closes the listener.
+func (l *unixListener) Close() error {
+	// this also closes the listener.
+	l.conn.forwards.remove(&net.UnixAddr{Name: l.socketPath, Net: "unix"})
+	m := streamLocalChannelForwardMsg{
+		l.socketPath,
+	}
+	ok, _, err := l.conn.SendRequest("cancel-streamlocal-forward@openssh.com", true, Marshal(&m))
+	if err == nil && !ok {
+		err = errors.New("ssh: cancel-streamlocal-forward@openssh.com failed")
+	}
+	return err
+}
+
+// Addr returns the listener's network address.
+func (l *unixListener) Addr() net.Addr {
+	return &net.UnixAddr{
+		Name: l.socketPath,
+		Net:  "unix",
+	}
+}
diff --git a/vendor/golang.org/x/crypto/ssh/tcpip.go b/vendor/golang.org/x/crypto/ssh/tcpip.go
new file mode 100644
index 000000000..ef5059a11
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/tcpip.go
@@ -0,0 +1,509 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"math/rand"
+	"net"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Listen requests the remote peer open a listening socket on
+// addr. Incoming connections will be available by calling Accept on
+// the returned net.Listener. The listener must be serviced, or the
+// SSH connection may hang.
+// N must be "tcp", "tcp4", "tcp6", or "unix".
+func (c *Client) Listen(n, addr string) (net.Listener, error) {
+	switch n {
+	case "tcp", "tcp4", "tcp6":
+		laddr, err := net.ResolveTCPAddr(n, addr)
+		if err != nil {
+			return nil, err
+		}
+		return c.ListenTCP(laddr)
+	case "unix":
+		return c.ListenUnix(addr)
+	default:
+		return nil, fmt.Errorf("ssh: unsupported protocol: %s", n)
+	}
+}
+
+// Automatic port allocation is broken with OpenSSH before 6.0. See
+// also https://bugzilla.mindrot.org/show_bug.cgi?id=2017.  In
+// particular, OpenSSH 5.9 sends a channelOpenMsg with port number 0,
+// rather than the actual port number. This means you can never open
+// two different listeners with auto allocated ports. We work around
+// this by trying explicit ports until we succeed.
+
+const openSSHPrefix = "OpenSSH_"
+
+var portRandomizer = rand.New(rand.NewSource(time.Now().UnixNano()))
+
+// isBrokenOpenSSHVersion returns true if the given version string
+// specifies a version of OpenSSH that is known to have a bug in port
+// forwarding.
+func isBrokenOpenSSHVersion(versionStr string) bool {
+	i := strings.Index(versionStr, openSSHPrefix)
+	if i < 0 {
+		return false
+	}
+	i += len(openSSHPrefix)
+	j := i
+	for ; j < len(versionStr); j++ {
+		if versionStr[j] < '0' || versionStr[j] > '9' {
+			break
+		}
+	}
+	version, _ := strconv.Atoi(versionStr[i:j])
+	return version < 6
+}
+
+// autoPortListenWorkaround simulates automatic port allocation by
+// trying random ports repeatedly.
+func (c *Client) autoPortListenWorkaround(laddr *net.TCPAddr) (net.Listener, error) {
+	var sshListener net.Listener
+	var err error
+	const tries = 10
+	for i := 0; i < tries; i++ {
+		addr := *laddr
+		addr.Port = 1024 + portRandomizer.Intn(60000)
+		sshListener, err = c.ListenTCP(&addr)
+		if err == nil {
+			laddr.Port = addr.Port
+			return sshListener, err
+		}
+	}
+	return nil, fmt.Errorf("ssh: listen on random port failed after %d tries: %v", tries, err)
+}
+
+// RFC 4254 7.1
+type channelForwardMsg struct {
+	addr  string
+	rport uint32
+}
+
+// handleForwards starts goroutines handling forwarded connections.
+// It's called on first use by (*Client).ListenTCP to not launch
+// goroutines until needed.
+func (c *Client) handleForwards() {
+	go c.forwards.handleChannels(c.HandleChannelOpen("forwarded-tcpip"))
+	go c.forwards.handleChannels(c.HandleChannelOpen("forwarded-streamlocal@openssh.com"))
+}
+
+// ListenTCP requests the remote peer open a listening socket
+// on laddr. Incoming connections will be available by calling
+// Accept on the returned net.Listener.
+func (c *Client) ListenTCP(laddr *net.TCPAddr) (net.Listener, error) {
+	c.handleForwardsOnce.Do(c.handleForwards)
+	if laddr.Port == 0 && isBrokenOpenSSHVersion(string(c.ServerVersion())) {
+		return c.autoPortListenWorkaround(laddr)
+	}
+
+	m := channelForwardMsg{
+		laddr.IP.String(),
+		uint32(laddr.Port),
+	}
+	// send message
+	ok, resp, err := c.SendRequest("tcpip-forward", true, Marshal(&m))
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, errors.New("ssh: tcpip-forward request denied by peer")
+	}
+
+	// If the original port was 0, then the remote side will
+	// supply a real port number in the response.
+	if laddr.Port == 0 {
+		var p struct {
+			Port uint32
+		}
+		if err := Unmarshal(resp, &p); err != nil {
+			return nil, err
+		}
+		laddr.Port = int(p.Port)
+	}
+
+	// Register this forward, using the port number we obtained.
+	ch := c.forwards.add(laddr)
+
+	return &tcpListener{laddr, c, ch}, nil
+}
+
+// forwardList stores a mapping between remote
+// forward requests and the tcpListeners.
+type forwardList struct {
+	sync.Mutex
+	entries []forwardEntry
+}
+
+// forwardEntry represents an established mapping of a laddr on a
+// remote ssh server to a channel connected to a tcpListener.
+type forwardEntry struct {
+	laddr net.Addr
+	c     chan forward
+}
+
+// forward represents an incoming forwarded tcpip connection. The
+// arguments to add/remove/lookup should be address as specified in
+// the original forward-request.
+type forward struct {
+	newCh NewChannel // the ssh client channel underlying this forward
+	raddr net.Addr   // the raddr of the incoming connection
+}
+
+func (l *forwardList) add(addr net.Addr) chan forward {
+	l.Lock()
+	defer l.Unlock()
+	f := forwardEntry{
+		laddr: addr,
+		c:     make(chan forward, 1),
+	}
+	l.entries = append(l.entries, f)
+	return f.c
+}
+
+// See RFC 4254, section 7.2
+type forwardedTCPPayload struct {
+	Addr       string
+	Port       uint32
+	OriginAddr string
+	OriginPort uint32
+}
+
+// parseTCPAddr parses the originating address from the remote into a *net.TCPAddr.
+func parseTCPAddr(addr string, port uint32) (*net.TCPAddr, error) {
+	if port == 0 || port > 65535 {
+		return nil, fmt.Errorf("ssh: port number out of range: %d", port)
+	}
+	ip := net.ParseIP(string(addr))
+	if ip == nil {
+		return nil, fmt.Errorf("ssh: cannot parse IP address %q", addr)
+	}
+	return &net.TCPAddr{IP: ip, Port: int(port)}, nil
+}
+
+func (l *forwardList) handleChannels(in <-chan NewChannel) {
+	for ch := range in {
+		var (
+			laddr net.Addr
+			raddr net.Addr
+			err   error
+		)
+		switch channelType := ch.ChannelType(); channelType {
+		case "forwarded-tcpip":
+			var payload forwardedTCPPayload
+			if err = Unmarshal(ch.ExtraData(), &payload); err != nil {
+				ch.Reject(ConnectionFailed, "could not parse forwarded-tcpip payload: "+err.Error())
+				continue
+			}
+
+			// RFC 4254 section 7.2 specifies that incoming
+			// addresses should list the address, in string
+			// format. It is implied that this should be an IP
+			// address, as it would be impossible to connect to it
+			// otherwise.
+			laddr, err = parseTCPAddr(payload.Addr, payload.Port)
+			if err != nil {
+				ch.Reject(ConnectionFailed, err.Error())
+				continue
+			}
+			raddr, err = parseTCPAddr(payload.OriginAddr, payload.OriginPort)
+			if err != nil {
+				ch.Reject(ConnectionFailed, err.Error())
+				continue
+			}
+
+		case "forwarded-streamlocal@openssh.com":
+			var payload forwardedStreamLocalPayload
+			if err = Unmarshal(ch.ExtraData(), &payload); err != nil {
+				ch.Reject(ConnectionFailed, "could not parse forwarded-streamlocal@openssh.com payload: "+err.Error())
+				continue
+			}
+			laddr = &net.UnixAddr{
+				Name: payload.SocketPath,
+				Net:  "unix",
+			}
+			raddr = &net.UnixAddr{
+				Name: "@",
+				Net:  "unix",
+			}
+		default:
+			panic(fmt.Errorf("ssh: unknown channel type %s", channelType))
+		}
+		if ok := l.forward(laddr, raddr, ch); !ok {
+			// Section 7.2, implementations MUST reject spurious incoming
+			// connections.
+			ch.Reject(Prohibited, "no forward for address")
+			continue
+		}
+
+	}
+}
+
+// remove removes the forward entry, and the channel feeding its
+// listener.
+func (l *forwardList) remove(addr net.Addr) {
+	l.Lock()
+	defer l.Unlock()
+	for i, f := range l.entries {
+		if addr.Network() == f.laddr.Network() && addr.String() == f.laddr.String() {
+			l.entries = append(l.entries[:i], l.entries[i+1:]...)
+			close(f.c)
+			return
+		}
+	}
+}
+
+// closeAll closes and clears all forwards.
+func (l *forwardList) closeAll() {
+	l.Lock()
+	defer l.Unlock()
+	for _, f := range l.entries {
+		close(f.c)
+	}
+	l.entries = nil
+}
+
+func (l *forwardList) forward(laddr, raddr net.Addr, ch NewChannel) bool {
+	l.Lock()
+	defer l.Unlock()
+	for _, f := range l.entries {
+		if laddr.Network() == f.laddr.Network() && laddr.String() == f.laddr.String() {
+			f.c <- forward{newCh: ch, raddr: raddr}
+			return true
+		}
+	}
+	return false
+}
+
+type tcpListener struct {
+	laddr *net.TCPAddr
+
+	conn *Client
+	in   <-chan forward
+}
+
+// Accept waits for and returns the next connection to the listener.
+func (l *tcpListener) Accept() (net.Conn, error) {
+	s, ok := <-l.in
+	if !ok {
+		return nil, io.EOF
+	}
+	ch, incoming, err := s.newCh.Accept()
+	if err != nil {
+		return nil, err
+	}
+	go DiscardRequests(incoming)
+
+	return &chanConn{
+		Channel: ch,
+		laddr:   l.laddr,
+		raddr:   s.raddr,
+	}, nil
+}
+
+// Close closes the listener.
+func (l *tcpListener) Close() error {
+	m := channelForwardMsg{
+		l.laddr.IP.String(),
+		uint32(l.laddr.Port),
+	}
+
+	// this also closes the listener.
+	l.conn.forwards.remove(l.laddr)
+	ok, _, err := l.conn.SendRequest("cancel-tcpip-forward", true, Marshal(&m))
+	if err == nil && !ok {
+		err = errors.New("ssh: cancel-tcpip-forward failed")
+	}
+	return err
+}
+
+// Addr returns the listener's network address.
+func (l *tcpListener) Addr() net.Addr {
+	return l.laddr
+}
+
+// DialContext initiates a connection to the addr from the remote host.
+//
+// The provided Context must be non-nil. If the context expires before the
+// connection is complete, an error is returned. Once successfully connected,
+// any expiration of the context will not affect the connection.
+//
+// See func Dial for additional information.
+func (c *Client) DialContext(ctx context.Context, n, addr string) (net.Conn, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	type connErr struct {
+		conn net.Conn
+		err  error
+	}
+	ch := make(chan connErr)
+	go func() {
+		conn, err := c.Dial(n, addr)
+		select {
+		case ch <- connErr{conn, err}:
+		case <-ctx.Done():
+			if conn != nil {
+				conn.Close()
+			}
+		}
+	}()
+	select {
+	case res := <-ch:
+		return res.conn, res.err
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
+// Dial initiates a connection to the addr from the remote host.
+// The resulting connection has a zero LocalAddr() and RemoteAddr().
+func (c *Client) Dial(n, addr string) (net.Conn, error) {
+	var ch Channel
+	switch n {
+	case "tcp", "tcp4", "tcp6":
+		// Parse the address into host and numeric port.
+		host, portString, err := net.SplitHostPort(addr)
+		if err != nil {
+			return nil, err
+		}
+		port, err := strconv.ParseUint(portString, 10, 16)
+		if err != nil {
+			return nil, err
+		}
+		ch, err = c.dial(net.IPv4zero.String(), 0, host, int(port))
+		if err != nil {
+			return nil, err
+		}
+		// Use a zero address for local and remote address.
+		zeroAddr := &net.TCPAddr{
+			IP:   net.IPv4zero,
+			Port: 0,
+		}
+		return &chanConn{
+			Channel: ch,
+			laddr:   zeroAddr,
+			raddr:   zeroAddr,
+		}, nil
+	case "unix":
+		var err error
+		ch, err = c.dialStreamLocal(addr)
+		if err != nil {
+			return nil, err
+		}
+		return &chanConn{
+			Channel: ch,
+			laddr: &net.UnixAddr{
+				Name: "@",
+				Net:  "unix",
+			},
+			raddr: &net.UnixAddr{
+				Name: addr,
+				Net:  "unix",
+			},
+		}, nil
+	default:
+		return nil, fmt.Errorf("ssh: unsupported protocol: %s", n)
+	}
+}
+
+// DialTCP connects to the remote address raddr on the network net,
+// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is used
+// as the local address for the connection.
+func (c *Client) DialTCP(n string, laddr, raddr *net.TCPAddr) (net.Conn, error) {
+	if laddr == nil {
+		laddr = &net.TCPAddr{
+			IP:   net.IPv4zero,
+			Port: 0,
+		}
+	}
+	ch, err := c.dial(laddr.IP.String(), laddr.Port, raddr.IP.String(), raddr.Port)
+	if err != nil {
+		return nil, err
+	}
+	return &chanConn{
+		Channel: ch,
+		laddr:   laddr,
+		raddr:   raddr,
+	}, nil
+}
+
+// RFC 4254 7.2
+type channelOpenDirectMsg struct {
+	raddr string
+	rport uint32
+	laddr string
+	lport uint32
+}
+
+func (c *Client) dial(laddr string, lport int, raddr string, rport int) (Channel, error) {
+	msg := channelOpenDirectMsg{
+		raddr: raddr,
+		rport: uint32(rport),
+		laddr: laddr,
+		lport: uint32(lport),
+	}
+	ch, in, err := c.OpenChannel("direct-tcpip", Marshal(&msg))
+	if err != nil {
+		return nil, err
+	}
+	go DiscardRequests(in)
+	return ch, err
+}
+
+type tcpChan struct {
+	Channel // the backing channel
+}
+
+// chanConn fulfills the net.Conn interface without
+// the tcpChan having to hold laddr or raddr directly.
+type chanConn struct {
+	Channel
+	laddr, raddr net.Addr
+}
+
+// LocalAddr returns the local network address.
+func (t *chanConn) LocalAddr() net.Addr {
+	return t.laddr
+}
+
+// RemoteAddr returns the remote network address.
+func (t *chanConn) RemoteAddr() net.Addr {
+	return t.raddr
+}
+
+// SetDeadline sets the read and write deadlines associated
+// with the connection.
+func (t *chanConn) SetDeadline(deadline time.Time) error {
+	if err := t.SetReadDeadline(deadline); err != nil {
+		return err
+	}
+	return t.SetWriteDeadline(deadline)
+}
+
+// SetReadDeadline sets the read deadline.
+// A zero value for t means Read will not time out.
+// After the deadline, the error from Read will implement net.Error
+// with Timeout() == true.
+func (t *chanConn) SetReadDeadline(deadline time.Time) error {
+	// for compatibility with previous version,
+	// the error message contains "tcpChan"
+	return errors.New("ssh: tcpChan: deadline not supported")
+}
+
+// SetWriteDeadline exists to satisfy the net.Conn interface
+// but is not implemented by this type.  It always returns an error.
+func (t *chanConn) SetWriteDeadline(deadline time.Time) error {
+	return errors.New("ssh: tcpChan: deadline not supported")
+}
diff --git a/vendor/golang.org/x/crypto/ssh/transport.go b/vendor/golang.org/x/crypto/ssh/transport.go
new file mode 100644
index 000000000..0424d2d37
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/transport.go
@@ -0,0 +1,380 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssh
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"log"
+)
+
+// debugTransport if set, will print packet types as they go over the
+// wire. No message decoding is done, to minimize the impact on timing.
+const debugTransport = false
+
+const (
+	gcm128CipherID = "aes128-gcm@openssh.com"
+	gcm256CipherID = "aes256-gcm@openssh.com"
+	aes128cbcID    = "aes128-cbc"
+	tripledescbcID = "3des-cbc"
+)
+
+// packetConn represents a transport that implements packet based
+// operations.
+type packetConn interface {
+	// Encrypt and send a packet of data to the remote peer.
+	writePacket(packet []byte) error
+
+	// Read a packet from the connection. The read is blocking,
+	// i.e. if error is nil, then the returned byte slice is
+	// always non-empty.
+	readPacket() ([]byte, error)
+
+	// Close closes the write-side of the connection.
+	Close() error
+}
+
+// transport is the keyingTransport that implements the SSH packet
+// protocol.
+type transport struct {
+	reader connectionState
+	writer connectionState
+
+	bufReader *bufio.Reader
+	bufWriter *bufio.Writer
+	rand      io.Reader
+	isClient  bool
+	io.Closer
+
+	strictMode     bool
+	initialKEXDone bool
+}
+
+// packetCipher represents a combination of SSH encryption/MAC
+// protocol.  A single instance should be used for one direction only.
+type packetCipher interface {
+	// writeCipherPacket encrypts the packet and writes it to w. The
+	// contents of the packet are generally scrambled.
+	writeCipherPacket(seqnum uint32, w io.Writer, rand io.Reader, packet []byte) error
+
+	// readCipherPacket reads and decrypts a packet of data. The
+	// returned packet may be overwritten by future calls of
+	// readPacket.
+	readCipherPacket(seqnum uint32, r io.Reader) ([]byte, error)
+}
+
+// connectionState represents one side (read or write) of the
+// connection. This is necessary because each direction has its own
+// keys, and can even have its own algorithms
+type connectionState struct {
+	packetCipher
+	seqNum           uint32
+	dir              direction
+	pendingKeyChange chan packetCipher
+}
+
+func (t *transport) setStrictMode() error {
+	if t.reader.seqNum != 1 {
+		return errors.New("ssh: sequence number != 1 when strict KEX mode requested")
+	}
+	t.strictMode = true
+	return nil
+}
+
+func (t *transport) setInitialKEXDone() {
+	t.initialKEXDone = true
+}
+
+// prepareKeyChange sets up key material for a keychange. The key changes in
+// both directions are triggered by reading and writing a msgNewKey packet
+// respectively.
+func (t *transport) prepareKeyChange(algs *algorithms, kexResult *kexResult) error {
+	ciph, err := newPacketCipher(t.reader.dir, algs.r, kexResult)
+	if err != nil {
+		return err
+	}
+	t.reader.pendingKeyChange <- ciph
+
+	ciph, err = newPacketCipher(t.writer.dir, algs.w, kexResult)
+	if err != nil {
+		return err
+	}
+	t.writer.pendingKeyChange <- ciph
+
+	return nil
+}
+
+func (t *transport) printPacket(p []byte, write bool) {
+	if len(p) == 0 {
+		return
+	}
+	who := "server"
+	if t.isClient {
+		who = "client"
+	}
+	what := "read"
+	if write {
+		what = "write"
+	}
+
+	log.Println(what, who, p[0])
+}
+
+// Read and decrypt next packet.
+func (t *transport) readPacket() (p []byte, err error) {
+	for {
+		p, err = t.reader.readPacket(t.bufReader, t.strictMode)
+		if err != nil {
+			break
+		}
+		// in strict mode we pass through DEBUG and IGNORE packets only during the initial KEX
+		if len(p) == 0 || (t.strictMode && !t.initialKEXDone) || (p[0] != msgIgnore && p[0] != msgDebug) {
+			break
+		}
+	}
+	if debugTransport {
+		t.printPacket(p, false)
+	}
+
+	return p, err
+}
+
+func (s *connectionState) readPacket(r *bufio.Reader, strictMode bool) ([]byte, error) {
+	packet, err := s.packetCipher.readCipherPacket(s.seqNum, r)
+	s.seqNum++
+	if err == nil && len(packet) == 0 {
+		err = errors.New("ssh: zero length packet")
+	}
+
+	if len(packet) > 0 {
+		switch packet[0] {
+		case msgNewKeys:
+			select {
+			case cipher := <-s.pendingKeyChange:
+				s.packetCipher = cipher
+				if strictMode {
+					s.seqNum = 0
+				}
+			default:
+				return nil, errors.New("ssh: got bogus newkeys message")
+			}
+
+		case msgDisconnect:
+			// Transform a disconnect message into an
+			// error. Since this is lowest level at which
+			// we interpret message types, doing it here
+			// ensures that we don't have to handle it
+			// elsewhere.
+			var msg disconnectMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return nil, err
+			}
+			return nil, &msg
+		}
+	}
+
+	// The packet may point to an internal buffer, so copy the
+	// packet out here.
+	fresh := make([]byte, len(packet))
+	copy(fresh, packet)
+
+	return fresh, err
+}
+
+func (t *transport) writePacket(packet []byte) error {
+	if debugTransport {
+		t.printPacket(packet, true)
+	}
+	return t.writer.writePacket(t.bufWriter, t.rand, packet, t.strictMode)
+}
+
+func (s *connectionState) writePacket(w *bufio.Writer, rand io.Reader, packet []byte, strictMode bool) error {
+	changeKeys := len(packet) > 0 && packet[0] == msgNewKeys
+
+	err := s.packetCipher.writeCipherPacket(s.seqNum, w, rand, packet)
+	if err != nil {
+		return err
+	}
+	if err = w.Flush(); err != nil {
+		return err
+	}
+	s.seqNum++
+	if changeKeys {
+		select {
+		case cipher := <-s.pendingKeyChange:
+			s.packetCipher = cipher
+			if strictMode {
+				s.seqNum = 0
+			}
+		default:
+			panic("ssh: no key material for msgNewKeys")
+		}
+	}
+	return err
+}
+
+func newTransport(rwc io.ReadWriteCloser, rand io.Reader, isClient bool) *transport {
+	t := &transport{
+		bufReader: bufio.NewReader(rwc),
+		bufWriter: bufio.NewWriter(rwc),
+		rand:      rand,
+		reader: connectionState{
+			packetCipher:     &streamPacketCipher{cipher: noneCipher{}},
+			pendingKeyChange: make(chan packetCipher, 1),
+		},
+		writer: connectionState{
+			packetCipher:     &streamPacketCipher{cipher: noneCipher{}},
+			pendingKeyChange: make(chan packetCipher, 1),
+		},
+		Closer: rwc,
+	}
+	t.isClient = isClient
+
+	if isClient {
+		t.reader.dir = serverKeys
+		t.writer.dir = clientKeys
+	} else {
+		t.reader.dir = clientKeys
+		t.writer.dir = serverKeys
+	}
+
+	return t
+}
+
+type direction struct {
+	ivTag     []byte
+	keyTag    []byte
+	macKeyTag []byte
+}
+
+var (
+	serverKeys = direction{[]byte{'B'}, []byte{'D'}, []byte{'F'}}
+	clientKeys = direction{[]byte{'A'}, []byte{'C'}, []byte{'E'}}
+)
+
+// setupKeys sets the cipher and MAC keys from kex.K, kex.H and sessionId, as
+// described in RFC 4253, section 6.4. direction should either be serverKeys
+// (to setup server->client keys) or clientKeys (for client->server keys).
+func newPacketCipher(d direction, algs directionAlgorithms, kex *kexResult) (packetCipher, error) {
+	cipherMode := cipherModes[algs.Cipher]
+
+	iv := make([]byte, cipherMode.ivSize)
+	key := make([]byte, cipherMode.keySize)
+
+	generateKeyMaterial(iv, d.ivTag, kex)
+	generateKeyMaterial(key, d.keyTag, kex)
+
+	var macKey []byte
+	if !aeadCiphers[algs.Cipher] {
+		macMode := macModes[algs.MAC]
+		macKey = make([]byte, macMode.keySize)
+		generateKeyMaterial(macKey, d.macKeyTag, kex)
+	}
+
+	return cipherModes[algs.Cipher].create(key, iv, macKey, algs)
+}
+
+// generateKeyMaterial fills out with key material generated from tag, K, H
+// and sessionId, as specified in RFC 4253, section 7.2.
+func generateKeyMaterial(out, tag []byte, r *kexResult) {
+	var digestsSoFar []byte
+
+	h := r.Hash.New()
+	for len(out) > 0 {
+		h.Reset()
+		h.Write(r.K)
+		h.Write(r.H)
+
+		if len(digestsSoFar) == 0 {
+			h.Write(tag)
+			h.Write(r.SessionID)
+		} else {
+			h.Write(digestsSoFar)
+		}
+
+		digest := h.Sum(nil)
+		n := copy(out, digest)
+		out = out[n:]
+		if len(out) > 0 {
+			digestsSoFar = append(digestsSoFar, digest...)
+		}
+	}
+}
+
+const packageVersion = "SSH-2.0-Go"
+
+// Sends and receives a version line.  The versionLine string should
+// be US ASCII, start with "SSH-2.0-", and should not include a
+// newline. exchangeVersions returns the other side's version line.
+func exchangeVersions(rw io.ReadWriter, versionLine []byte) (them []byte, err error) {
+	// Contrary to the RFC, we do not ignore lines that don't
+	// start with "SSH-2.0-" to make the library usable with
+	// nonconforming servers.
+	for _, c := range versionLine {
+		// The spec disallows non US-ASCII chars, and
+		// specifically forbids null chars.
+		if c < 32 {
+			return nil, errors.New("ssh: junk character in version line")
+		}
+	}
+	if _, err = rw.Write(append(versionLine, '\r', '\n')); err != nil {
+		return
+	}
+
+	them, err = readVersion(rw)
+	return them, err
+}
+
+// maxVersionStringBytes is the maximum number of bytes that we'll
+// accept as a version string. RFC 4253 section 4.2 limits this at 255
+// chars
+const maxVersionStringBytes = 255
+
+// Read version string as specified by RFC 4253, section 4.2.
+func readVersion(r io.Reader) ([]byte, error) {
+	versionString := make([]byte, 0, 64)
+	var ok bool
+	var buf [1]byte
+
+	for length := 0; length < maxVersionStringBytes; length++ {
+		_, err := io.ReadFull(r, buf[:])
+		if err != nil {
+			return nil, err
+		}
+		// The RFC says that the version should be terminated with \r\n
+		// but several SSH servers actually only send a \n.
+		if buf[0] == '\n' {
+			if !bytes.HasPrefix(versionString, []byte("SSH-")) {
+				// RFC 4253 says we need to ignore all version string lines
+				// except the one containing the SSH version (provided that
+				// all the lines do not exceed 255 bytes in total).
+				versionString = versionString[:0]
+				continue
+			}
+			ok = true
+			break
+		}
+
+		// non ASCII chars are disallowed, but we are lenient,
+		// since Go doesn't use null-terminated strings.
+
+		// The RFC allows a comment after a space, however,
+		// all of it (version and comments) goes into the
+		// session hash.
+		versionString = append(versionString, buf[0])
+	}
+
+	if !ok {
+		return nil, errors.New("ssh: overflow reading version string")
+	}
+
+	// There might be a '\r' on the end which we should remove.
+	if len(versionString) > 0 && versionString[len(versionString)-1] == '\r' {
+		versionString = versionString[:len(versionString)-1]
+	}
+	return versionString, nil
+}
diff --git a/vendor/golang.org/x/sys/cpu/asm_aix_ppc64.s b/vendor/golang.org/x/sys/cpu/asm_aix_ppc64.s
new file mode 100644
index 000000000..269e173ca
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/asm_aix_ppc64.s
@@ -0,0 +1,17 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc
+
+#include "textflag.h"
+
+//
+// System calls for ppc64, AIX are implemented in runtime/syscall_aix.go
+//
+
+TEXT ·syscall6(SB),NOSPLIT,$0-88
+	JMP	syscall·syscall6(SB)
+
+TEXT ·rawSyscall6(SB),NOSPLIT,$0-88
+	JMP	syscall·rawSyscall6(SB)
diff --git a/vendor/golang.org/x/sys/cpu/byteorder.go b/vendor/golang.org/x/sys/cpu/byteorder.go
new file mode 100644
index 000000000..271055be0
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/byteorder.go
@@ -0,0 +1,66 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"runtime"
+)
+
+// byteOrder is a subset of encoding/binary.ByteOrder.
+type byteOrder interface {
+	Uint32([]byte) uint32
+	Uint64([]byte) uint64
+}
+
+type littleEndian struct{}
+type bigEndian struct{}
+
+func (littleEndian) Uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func (littleEndian) Uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func (bigEndian) Uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+}
+
+func (bigEndian) Uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
+		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
+}
+
+// hostByteOrder returns littleEndian on little-endian machines and
+// bigEndian on big-endian machines.
+func hostByteOrder() byteOrder {
+	switch runtime.GOARCH {
+	case "386", "amd64", "amd64p32",
+		"alpha",
+		"arm", "arm64",
+		"loong64",
+		"mipsle", "mips64le", "mips64p32le",
+		"nios2",
+		"ppc64le",
+		"riscv", "riscv64",
+		"sh":
+		return littleEndian{}
+	case "armbe", "arm64be",
+		"m68k",
+		"mips", "mips64", "mips64p32",
+		"ppc", "ppc64",
+		"s390", "s390x",
+		"shbe",
+		"sparc", "sparc64":
+		return bigEndian{}
+	}
+	panic("unknown architecture")
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu.go b/vendor/golang.org/x/sys/cpu/cpu.go
new file mode 100644
index 000000000..8fa707aa4
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu.go
@@ -0,0 +1,291 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package cpu implements processor feature detection for
+// various CPU architectures.
+package cpu
+
+import (
+	"os"
+	"strings"
+)
+
+// Initialized reports whether the CPU features were initialized.
+//
+// For some GOOS/GOARCH combinations initialization of the CPU features depends
+// on reading an operating specific file, e.g. /proc/self/auxv on linux/arm
+// Initialized will report false if reading the file fails.
+var Initialized bool
+
+// CacheLinePad is used to pad structs to avoid false sharing.
+type CacheLinePad struct{ _ [cacheLineSize]byte }
+
+// X86 contains the supported CPU features of the
+// current X86/AMD64 platform. If the current platform
+// is not X86/AMD64 then all feature flags are false.
+//
+// X86 is padded to avoid false sharing. Further the HasAVX
+// and HasAVX2 are only set if the OS supports XMM and YMM
+// registers in addition to the CPUID feature bit being set.
+var X86 struct {
+	_                   CacheLinePad
+	HasAES              bool // AES hardware implementation (AES NI)
+	HasADX              bool // Multi-precision add-carry instruction extensions
+	HasAVX              bool // Advanced vector extension
+	HasAVX2             bool // Advanced vector extension 2
+	HasAVX512           bool // Advanced vector extension 512
+	HasAVX512F          bool // Advanced vector extension 512 Foundation Instructions
+	HasAVX512CD         bool // Advanced vector extension 512 Conflict Detection Instructions
+	HasAVX512ER         bool // Advanced vector extension 512 Exponential and Reciprocal Instructions
+	HasAVX512PF         bool // Advanced vector extension 512 Prefetch Instructions
+	HasAVX512VL         bool // Advanced vector extension 512 Vector Length Extensions
+	HasAVX512BW         bool // Advanced vector extension 512 Byte and Word Instructions
+	HasAVX512DQ         bool // Advanced vector extension 512 Doubleword and Quadword Instructions
+	HasAVX512IFMA       bool // Advanced vector extension 512 Integer Fused Multiply Add
+	HasAVX512VBMI       bool // Advanced vector extension 512 Vector Byte Manipulation Instructions
+	HasAVX5124VNNIW     bool // Advanced vector extension 512 Vector Neural Network Instructions Word variable precision
+	HasAVX5124FMAPS     bool // Advanced vector extension 512 Fused Multiply Accumulation Packed Single precision
+	HasAVX512VPOPCNTDQ  bool // Advanced vector extension 512 Double and quad word population count instructions
+	HasAVX512VPCLMULQDQ bool // Advanced vector extension 512 Vector carry-less multiply operations
+	HasAVX512VNNI       bool // Advanced vector extension 512 Vector Neural Network Instructions
+	HasAVX512GFNI       bool // Advanced vector extension 512 Galois field New Instructions
+	HasAVX512VAES       bool // Advanced vector extension 512 Vector AES instructions
+	HasAVX512VBMI2      bool // Advanced vector extension 512 Vector Byte Manipulation Instructions 2
+	HasAVX512BITALG     bool // Advanced vector extension 512 Bit Algorithms
+	HasAVX512BF16       bool // Advanced vector extension 512 BFloat16 Instructions
+	HasAMXTile          bool // Advanced Matrix Extension Tile instructions
+	HasAMXInt8          bool // Advanced Matrix Extension Int8 instructions
+	HasAMXBF16          bool // Advanced Matrix Extension BFloat16 instructions
+	HasBMI1             bool // Bit manipulation instruction set 1
+	HasBMI2             bool // Bit manipulation instruction set 2
+	HasCX16             bool // Compare and exchange 16 Bytes
+	HasERMS             bool // Enhanced REP for MOVSB and STOSB
+	HasFMA              bool // Fused-multiply-add instructions
+	HasOSXSAVE          bool // OS supports XSAVE/XRESTOR for saving/restoring XMM registers.
+	HasPCLMULQDQ        bool // PCLMULQDQ instruction - most often used for AES-GCM
+	HasPOPCNT           bool // Hamming weight instruction POPCNT.
+	HasRDRAND           bool // RDRAND instruction (on-chip random number generator)
+	HasRDSEED           bool // RDSEED instruction (on-chip random number generator)
+	HasSSE2             bool // Streaming SIMD extension 2 (always available on amd64)
+	HasSSE3             bool // Streaming SIMD extension 3
+	HasSSSE3            bool // Supplemental streaming SIMD extension 3
+	HasSSE41            bool // Streaming SIMD extension 4 and 4.1
+	HasSSE42            bool // Streaming SIMD extension 4 and 4.2
+	_                   CacheLinePad
+}
+
+// ARM64 contains the supported CPU features of the
+// current ARMv8(aarch64) platform. If the current platform
+// is not arm64 then all feature flags are false.
+var ARM64 struct {
+	_           CacheLinePad
+	HasFP       bool // Floating-point instruction set (always available)
+	HasASIMD    bool // Advanced SIMD (always available)
+	HasEVTSTRM  bool // Event stream support
+	HasAES      bool // AES hardware implementation
+	HasPMULL    bool // Polynomial multiplication instruction set
+	HasSHA1     bool // SHA1 hardware implementation
+	HasSHA2     bool // SHA2 hardware implementation
+	HasCRC32    bool // CRC32 hardware implementation
+	HasATOMICS  bool // Atomic memory operation instruction set
+	HasFPHP     bool // Half precision floating-point instruction set
+	HasASIMDHP  bool // Advanced SIMD half precision instruction set
+	HasCPUID    bool // CPUID identification scheme registers
+	HasASIMDRDM bool // Rounding double multiply add/subtract instruction set
+	HasJSCVT    bool // Javascript conversion from floating-point to integer
+	HasFCMA     bool // Floating-point multiplication and addition of complex numbers
+	HasLRCPC    bool // Release Consistent processor consistent support
+	HasDCPOP    bool // Persistent memory support
+	HasSHA3     bool // SHA3 hardware implementation
+	HasSM3      bool // SM3 hardware implementation
+	HasSM4      bool // SM4 hardware implementation
+	HasASIMDDP  bool // Advanced SIMD double precision instruction set
+	HasSHA512   bool // SHA512 hardware implementation
+	HasSVE      bool // Scalable Vector Extensions
+	HasSVE2     bool // Scalable Vector Extensions 2
+	HasASIMDFHM bool // Advanced SIMD multiplication FP16 to FP32
+	_           CacheLinePad
+}
+
+// ARM contains the supported CPU features of the current ARM (32-bit) platform.
+// All feature flags are false if:
+//  1. the current platform is not arm, or
+//  2. the current operating system is not Linux.
+var ARM struct {
+	_           CacheLinePad
+	HasSWP      bool // SWP instruction support
+	HasHALF     bool // Half-word load and store support
+	HasTHUMB    bool // ARM Thumb instruction set
+	Has26BIT    bool // Address space limited to 26-bits
+	HasFASTMUL  bool // 32-bit operand, 64-bit result multiplication support
+	HasFPA      bool // Floating point arithmetic support
+	HasVFP      bool // Vector floating point support
+	HasEDSP     bool // DSP Extensions support
+	HasJAVA     bool // Java instruction set
+	HasIWMMXT   bool // Intel Wireless MMX technology support
+	HasCRUNCH   bool // MaverickCrunch context switching and handling
+	HasTHUMBEE  bool // Thumb EE instruction set
+	HasNEON     bool // NEON instruction set
+	HasVFPv3    bool // Vector floating point version 3 support
+	HasVFPv3D16 bool // Vector floating point version 3 D8-D15
+	HasTLS      bool // Thread local storage support
+	HasVFPv4    bool // Vector floating point version 4 support
+	HasIDIVA    bool // Integer divide instruction support in ARM mode
+	HasIDIVT    bool // Integer divide instruction support in Thumb mode
+	HasVFPD32   bool // Vector floating point version 3 D15-D31
+	HasLPAE     bool // Large Physical Address Extensions
+	HasEVTSTRM  bool // Event stream support
+	HasAES      bool // AES hardware implementation
+	HasPMULL    bool // Polynomial multiplication instruction set
+	HasSHA1     bool // SHA1 hardware implementation
+	HasSHA2     bool // SHA2 hardware implementation
+	HasCRC32    bool // CRC32 hardware implementation
+	_           CacheLinePad
+}
+
+// MIPS64X contains the supported CPU features of the current mips64/mips64le
+// platforms. If the current platform is not mips64/mips64le or the current
+// operating system is not Linux then all feature flags are false.
+var MIPS64X struct {
+	_      CacheLinePad
+	HasMSA bool // MIPS SIMD architecture
+	_      CacheLinePad
+}
+
+// PPC64 contains the supported CPU features of the current ppc64/ppc64le platforms.
+// If the current platform is not ppc64/ppc64le then all feature flags are false.
+//
+// For ppc64/ppc64le, it is safe to check only for ISA level starting on ISA v3.00,
+// since there are no optional categories. There are some exceptions that also
+// require kernel support to work (DARN, SCV), so there are feature bits for
+// those as well. The struct is padded to avoid false sharing.
+var PPC64 struct {
+	_        CacheLinePad
+	HasDARN  bool // Hardware random number generator (requires kernel enablement)
+	HasSCV   bool // Syscall vectored (requires kernel enablement)
+	IsPOWER8 bool // ISA v2.07 (POWER8)
+	IsPOWER9 bool // ISA v3.00 (POWER9), implies IsPOWER8
+	_        CacheLinePad
+}
+
+// S390X contains the supported CPU features of the current IBM Z
+// (s390x) platform. If the current platform is not IBM Z then all
+// feature flags are false.
+//
+// S390X is padded to avoid false sharing. Further HasVX is only set
+// if the OS supports vector registers in addition to the STFLE
+// feature bit being set.
+var S390X struct {
+	_         CacheLinePad
+	HasZARCH  bool // z/Architecture mode is active [mandatory]
+	HasSTFLE  bool // store facility list extended
+	HasLDISP  bool // long (20-bit) displacements
+	HasEIMM   bool // 32-bit immediates
+	HasDFP    bool // decimal floating point
+	HasETF3EH bool // ETF-3 enhanced
+	HasMSA    bool // message security assist (CPACF)
+	HasAES    bool // KM-AES{128,192,256} functions
+	HasAESCBC bool // KMC-AES{128,192,256} functions
+	HasAESCTR bool // KMCTR-AES{128,192,256} functions
+	HasAESGCM bool // KMA-GCM-AES{128,192,256} functions
+	HasGHASH  bool // KIMD-GHASH function
+	HasSHA1   bool // K{I,L}MD-SHA-1 functions
+	HasSHA256 bool // K{I,L}MD-SHA-256 functions
+	HasSHA512 bool // K{I,L}MD-SHA-512 functions
+	HasSHA3   bool // K{I,L}MD-SHA3-{224,256,384,512} and K{I,L}MD-SHAKE-{128,256} functions
+	HasVX     bool // vector facility
+	HasVXE    bool // vector-enhancements facility 1
+	_         CacheLinePad
+}
+
+func init() {
+	archInit()
+	initOptions()
+	processOptions()
+}
+
+// options contains the cpu debug options that can be used in GODEBUG.
+// Options are arch dependent and are added by the arch specific initOptions functions.
+// Features that are mandatory for the specific GOARCH should have the Required field set
+// (e.g. SSE2 on amd64).
+var options []option
+
+// Option names should be lower case. e.g. avx instead of AVX.
+type option struct {
+	Name      string
+	Feature   *bool
+	Specified bool // whether feature value was specified in GODEBUG
+	Enable    bool // whether feature should be enabled
+	Required  bool // whether feature is mandatory and can not be disabled
+}
+
+func processOptions() {
+	env := os.Getenv("GODEBUG")
+field:
+	for env != "" {
+		field := ""
+		i := strings.IndexByte(env, ',')
+		if i < 0 {
+			field, env = env, ""
+		} else {
+			field, env = env[:i], env[i+1:]
+		}
+		if len(field) < 4 || field[:4] != "cpu." {
+			continue
+		}
+		i = strings.IndexByte(field, '=')
+		if i < 0 {
+			print("GODEBUG sys/cpu: no value specified for \"", field, "\"\n")
+			continue
+		}
+		key, value := field[4:i], field[i+1:] // e.g. "SSE2", "on"
+
+		var enable bool
+		switch value {
+		case "on":
+			enable = true
+		case "off":
+			enable = false
+		default:
+			print("GODEBUG sys/cpu: value \"", value, "\" not supported for cpu option \"", key, "\"\n")
+			continue field
+		}
+
+		if key == "all" {
+			for i := range options {
+				options[i].Specified = true
+				options[i].Enable = enable || options[i].Required
+			}
+			continue field
+		}
+
+		for i := range options {
+			if options[i].Name == key {
+				options[i].Specified = true
+				options[i].Enable = enable
+				continue field
+			}
+		}
+
+		print("GODEBUG sys/cpu: unknown cpu feature \"", key, "\"\n")
+	}
+
+	for _, o := range options {
+		if !o.Specified {
+			continue
+		}
+
+		if o.Enable && !*o.Feature {
+			print("GODEBUG sys/cpu: can not enable \"", o.Name, "\", missing CPU support\n")
+			continue
+		}
+
+		if !o.Enable && o.Required {
+			print("GODEBUG sys/cpu: can not disable \"", o.Name, "\", required CPU feature\n")
+			continue
+		}
+
+		*o.Feature = o.Enable
+	}
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_aix.go b/vendor/golang.org/x/sys/cpu/cpu_aix.go
new file mode 100644
index 000000000..9bf0c32eb
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_aix.go
@@ -0,0 +1,33 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build aix
+
+package cpu
+
+const (
+	// getsystemcfg constants
+	_SC_IMPL     = 2
+	_IMPL_POWER8 = 0x10000
+	_IMPL_POWER9 = 0x20000
+)
+
+func archInit() {
+	impl := getsystemcfg(_SC_IMPL)
+	if impl&_IMPL_POWER8 != 0 {
+		PPC64.IsPOWER8 = true
+	}
+	if impl&_IMPL_POWER9 != 0 {
+		PPC64.IsPOWER8 = true
+		PPC64.IsPOWER9 = true
+	}
+
+	Initialized = true
+}
+
+func getsystemcfg(label int) (n uint64) {
+	r0, _ := callgetsystemcfg(label)
+	n = uint64(r0)
+	return
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_arm.go b/vendor/golang.org/x/sys/cpu/cpu_arm.go
new file mode 100644
index 000000000..301b752e9
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_arm.go
@@ -0,0 +1,73 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+const cacheLineSize = 32
+
+// HWCAP/HWCAP2 bits.
+// These are specific to Linux.
+const (
+	hwcap_SWP       = 1 << 0
+	hwcap_HALF      = 1 << 1
+	hwcap_THUMB     = 1 << 2
+	hwcap_26BIT     = 1 << 3
+	hwcap_FAST_MULT = 1 << 4
+	hwcap_FPA       = 1 << 5
+	hwcap_VFP       = 1 << 6
+	hwcap_EDSP      = 1 << 7
+	hwcap_JAVA      = 1 << 8
+	hwcap_IWMMXT    = 1 << 9
+	hwcap_CRUNCH    = 1 << 10
+	hwcap_THUMBEE   = 1 << 11
+	hwcap_NEON      = 1 << 12
+	hwcap_VFPv3     = 1 << 13
+	hwcap_VFPv3D16  = 1 << 14
+	hwcap_TLS       = 1 << 15
+	hwcap_VFPv4     = 1 << 16
+	hwcap_IDIVA     = 1 << 17
+	hwcap_IDIVT     = 1 << 18
+	hwcap_VFPD32    = 1 << 19
+	hwcap_LPAE      = 1 << 20
+	hwcap_EVTSTRM   = 1 << 21
+
+	hwcap2_AES   = 1 << 0
+	hwcap2_PMULL = 1 << 1
+	hwcap2_SHA1  = 1 << 2
+	hwcap2_SHA2  = 1 << 3
+	hwcap2_CRC32 = 1 << 4
+)
+
+func initOptions() {
+	options = []option{
+		{Name: "pmull", Feature: &ARM.HasPMULL},
+		{Name: "sha1", Feature: &ARM.HasSHA1},
+		{Name: "sha2", Feature: &ARM.HasSHA2},
+		{Name: "swp", Feature: &ARM.HasSWP},
+		{Name: "thumb", Feature: &ARM.HasTHUMB},
+		{Name: "thumbee", Feature: &ARM.HasTHUMBEE},
+		{Name: "tls", Feature: &ARM.HasTLS},
+		{Name: "vfp", Feature: &ARM.HasVFP},
+		{Name: "vfpd32", Feature: &ARM.HasVFPD32},
+		{Name: "vfpv3", Feature: &ARM.HasVFPv3},
+		{Name: "vfpv3d16", Feature: &ARM.HasVFPv3D16},
+		{Name: "vfpv4", Feature: &ARM.HasVFPv4},
+		{Name: "half", Feature: &ARM.HasHALF},
+		{Name: "26bit", Feature: &ARM.Has26BIT},
+		{Name: "fastmul", Feature: &ARM.HasFASTMUL},
+		{Name: "fpa", Feature: &ARM.HasFPA},
+		{Name: "edsp", Feature: &ARM.HasEDSP},
+		{Name: "java", Feature: &ARM.HasJAVA},
+		{Name: "iwmmxt", Feature: &ARM.HasIWMMXT},
+		{Name: "crunch", Feature: &ARM.HasCRUNCH},
+		{Name: "neon", Feature: &ARM.HasNEON},
+		{Name: "idivt", Feature: &ARM.HasIDIVT},
+		{Name: "idiva", Feature: &ARM.HasIDIVA},
+		{Name: "lpae", Feature: &ARM.HasLPAE},
+		{Name: "evtstrm", Feature: &ARM.HasEVTSTRM},
+		{Name: "aes", Feature: &ARM.HasAES},
+		{Name: "crc32", Feature: &ARM.HasCRC32},
+	}
+
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_arm64.go
new file mode 100644
index 000000000..0e27a21e1
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_arm64.go
@@ -0,0 +1,182 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import "runtime"
+
+// cacheLineSize is used to prevent false sharing of cache lines.
+// We choose 128 because Apple Silicon, a.k.a. M1, has 128-byte cache line size.
+// It doesn't cost much and is much more future-proof.
+const cacheLineSize = 128
+
+func initOptions() {
+	options = []option{
+		{Name: "fp", Feature: &ARM64.HasFP},
+		{Name: "asimd", Feature: &ARM64.HasASIMD},
+		{Name: "evstrm", Feature: &ARM64.HasEVTSTRM},
+		{Name: "aes", Feature: &ARM64.HasAES},
+		{Name: "fphp", Feature: &ARM64.HasFPHP},
+		{Name: "jscvt", Feature: &ARM64.HasJSCVT},
+		{Name: "lrcpc", Feature: &ARM64.HasLRCPC},
+		{Name: "pmull", Feature: &ARM64.HasPMULL},
+		{Name: "sha1", Feature: &ARM64.HasSHA1},
+		{Name: "sha2", Feature: &ARM64.HasSHA2},
+		{Name: "sha3", Feature: &ARM64.HasSHA3},
+		{Name: "sha512", Feature: &ARM64.HasSHA512},
+		{Name: "sm3", Feature: &ARM64.HasSM3},
+		{Name: "sm4", Feature: &ARM64.HasSM4},
+		{Name: "sve", Feature: &ARM64.HasSVE},
+		{Name: "sve2", Feature: &ARM64.HasSVE2},
+		{Name: "crc32", Feature: &ARM64.HasCRC32},
+		{Name: "atomics", Feature: &ARM64.HasATOMICS},
+		{Name: "asimdhp", Feature: &ARM64.HasASIMDHP},
+		{Name: "cpuid", Feature: &ARM64.HasCPUID},
+		{Name: "asimrdm", Feature: &ARM64.HasASIMDRDM},
+		{Name: "fcma", Feature: &ARM64.HasFCMA},
+		{Name: "dcpop", Feature: &ARM64.HasDCPOP},
+		{Name: "asimddp", Feature: &ARM64.HasASIMDDP},
+		{Name: "asimdfhm", Feature: &ARM64.HasASIMDFHM},
+	}
+}
+
+func archInit() {
+	switch runtime.GOOS {
+	case "freebsd":
+		readARM64Registers()
+	case "linux", "netbsd", "openbsd":
+		doinit()
+	default:
+		// Many platforms don't seem to allow reading these registers.
+		setMinimalFeatures()
+	}
+}
+
+// setMinimalFeatures fakes the minimal ARM64 features expected by
+// TestARM64minimalFeatures.
+func setMinimalFeatures() {
+	ARM64.HasASIMD = true
+	ARM64.HasFP = true
+}
+
+func readARM64Registers() {
+	Initialized = true
+
+	parseARM64SystemRegisters(getisar0(), getisar1(), getpfr0())
+}
+
+func parseARM64SystemRegisters(isar0, isar1, pfr0 uint64) {
+	// ID_AA64ISAR0_EL1
+	switch extractBits(isar0, 4, 7) {
+	case 1:
+		ARM64.HasAES = true
+	case 2:
+		ARM64.HasAES = true
+		ARM64.HasPMULL = true
+	}
+
+	switch extractBits(isar0, 8, 11) {
+	case 1:
+		ARM64.HasSHA1 = true
+	}
+
+	switch extractBits(isar0, 12, 15) {
+	case 1:
+		ARM64.HasSHA2 = true
+	case 2:
+		ARM64.HasSHA2 = true
+		ARM64.HasSHA512 = true
+	}
+
+	switch extractBits(isar0, 16, 19) {
+	case 1:
+		ARM64.HasCRC32 = true
+	}
+
+	switch extractBits(isar0, 20, 23) {
+	case 2:
+		ARM64.HasATOMICS = true
+	}
+
+	switch extractBits(isar0, 28, 31) {
+	case 1:
+		ARM64.HasASIMDRDM = true
+	}
+
+	switch extractBits(isar0, 32, 35) {
+	case 1:
+		ARM64.HasSHA3 = true
+	}
+
+	switch extractBits(isar0, 36, 39) {
+	case 1:
+		ARM64.HasSM3 = true
+	}
+
+	switch extractBits(isar0, 40, 43) {
+	case 1:
+		ARM64.HasSM4 = true
+	}
+
+	switch extractBits(isar0, 44, 47) {
+	case 1:
+		ARM64.HasASIMDDP = true
+	}
+
+	// ID_AA64ISAR1_EL1
+	switch extractBits(isar1, 0, 3) {
+	case 1:
+		ARM64.HasDCPOP = true
+	}
+
+	switch extractBits(isar1, 12, 15) {
+	case 1:
+		ARM64.HasJSCVT = true
+	}
+
+	switch extractBits(isar1, 16, 19) {
+	case 1:
+		ARM64.HasFCMA = true
+	}
+
+	switch extractBits(isar1, 20, 23) {
+	case 1:
+		ARM64.HasLRCPC = true
+	}
+
+	// ID_AA64PFR0_EL1
+	switch extractBits(pfr0, 16, 19) {
+	case 0:
+		ARM64.HasFP = true
+	case 1:
+		ARM64.HasFP = true
+		ARM64.HasFPHP = true
+	}
+
+	switch extractBits(pfr0, 20, 23) {
+	case 0:
+		ARM64.HasASIMD = true
+	case 1:
+		ARM64.HasASIMD = true
+		ARM64.HasASIMDHP = true
+	}
+
+	switch extractBits(pfr0, 32, 35) {
+	case 1:
+		ARM64.HasSVE = true
+
+		parseARM64SVERegister(getzfr0())
+	}
+}
+
+func parseARM64SVERegister(zfr0 uint64) {
+	switch extractBits(zfr0, 0, 3) {
+	case 1:
+		ARM64.HasSVE2 = true
+	}
+}
+
+func extractBits(data uint64, start, end uint) uint {
+	return (uint)(data>>start) & ((1 << (end - start + 1)) - 1)
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_arm64.s b/vendor/golang.org/x/sys/cpu/cpu_arm64.s
new file mode 100644
index 000000000..22cc99844
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_arm64.s
@@ -0,0 +1,39 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc
+
+#include "textflag.h"
+
+// func getisar0() uint64
+TEXT ·getisar0(SB),NOSPLIT,$0-8
+	// get Instruction Set Attributes 0 into x0
+	// mrs x0, ID_AA64ISAR0_EL1 = d5380600
+	WORD	$0xd5380600
+	MOVD	R0, ret+0(FP)
+	RET
+
+// func getisar1() uint64
+TEXT ·getisar1(SB),NOSPLIT,$0-8
+	// get Instruction Set Attributes 1 into x0
+	// mrs x0, ID_AA64ISAR1_EL1 = d5380620
+	WORD	$0xd5380620
+	MOVD	R0, ret+0(FP)
+	RET
+
+// func getpfr0() uint64
+TEXT ·getpfr0(SB),NOSPLIT,$0-8
+	// get Processor Feature Register 0 into x0
+	// mrs x0, ID_AA64PFR0_EL1 = d5380400
+	WORD	$0xd5380400
+	MOVD	R0, ret+0(FP)
+	RET
+
+// func getzfr0() uint64
+TEXT ·getzfr0(SB),NOSPLIT,$0-8
+	// get SVE Feature Register 0 into x0
+	// mrs	x0, ID_AA64ZFR0_EL1 = d5380480
+	WORD $0xd5380480
+	MOVD	R0, ret+0(FP)
+	RET
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gc_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_gc_arm64.go
new file mode 100644
index 000000000..6ac6e1efb
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gc_arm64.go
@@ -0,0 +1,12 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc
+
+package cpu
+
+func getisar0() uint64
+func getisar1() uint64
+func getpfr0() uint64
+func getzfr0() uint64
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gc_s390x.go b/vendor/golang.org/x/sys/cpu/cpu_gc_s390x.go
new file mode 100644
index 000000000..c8ae6ddc1
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gc_s390x.go
@@ -0,0 +1,21 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc
+
+package cpu
+
+// haveAsmFunctions reports whether the other functions in this file can
+// be safely called.
+func haveAsmFunctions() bool { return true }
+
+// The following feature detection functions are defined in cpu_s390x.s.
+// They are likely to be expensive to call so the results should be cached.
+func stfle() facilityList
+func kmQuery() queryResult
+func kmcQuery() queryResult
+func kmctrQuery() queryResult
+func kmaQuery() queryResult
+func kimdQuery() queryResult
+func klmdQuery() queryResult
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gc_x86.go b/vendor/golang.org/x/sys/cpu/cpu_gc_x86.go
new file mode 100644
index 000000000..910728fb1
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gc_x86.go
@@ -0,0 +1,15 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (386 || amd64 || amd64p32) && gc
+
+package cpu
+
+// cpuid is implemented in cpu_x86.s for gc compiler
+// and in cpu_gccgo.c for gccgo.
+func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
+
+// xgetbv with ecx = 0 is implemented in cpu_x86.s for gc compiler
+// and in cpu_gccgo.c for gccgo.
+func xgetbv() (eax, edx uint32)
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gccgo_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_gccgo_arm64.go
new file mode 100644
index 000000000..7f1946780
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gccgo_arm64.go
@@ -0,0 +1,11 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gccgo
+
+package cpu
+
+func getisar0() uint64 { return 0 }
+func getisar1() uint64 { return 0 }
+func getpfr0() uint64  { return 0 }
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gccgo_s390x.go b/vendor/golang.org/x/sys/cpu/cpu_gccgo_s390x.go
new file mode 100644
index 000000000..9526d2ce3
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gccgo_s390x.go
@@ -0,0 +1,22 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gccgo
+
+package cpu
+
+// haveAsmFunctions reports whether the other functions in this file can
+// be safely called.
+func haveAsmFunctions() bool { return false }
+
+// TODO(mundaym): the following feature detection functions are currently
+// stubs. See https://golang.org/cl/162887 for how to fix this.
+// They are likely to be expensive to call so the results should be cached.
+func stfle() facilityList     { panic("not implemented for gccgo") }
+func kmQuery() queryResult    { panic("not implemented for gccgo") }
+func kmcQuery() queryResult   { panic("not implemented for gccgo") }
+func kmctrQuery() queryResult { panic("not implemented for gccgo") }
+func kmaQuery() queryResult   { panic("not implemented for gccgo") }
+func kimdQuery() queryResult  { panic("not implemented for gccgo") }
+func klmdQuery() queryResult  { panic("not implemented for gccgo") }
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gccgo_x86.c b/vendor/golang.org/x/sys/cpu/cpu_gccgo_x86.c
new file mode 100644
index 000000000..3f73a05dc
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gccgo_x86.c
@@ -0,0 +1,37 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (386 || amd64 || amd64p32) && gccgo
+
+#include <cpuid.h>
+#include <stdint.h>
+#include <x86intrin.h>
+
+// Need to wrap __get_cpuid_count because it's declared as static.
+int
+gccgoGetCpuidCount(uint32_t leaf, uint32_t subleaf,
+                   uint32_t *eax, uint32_t *ebx,
+                   uint32_t *ecx, uint32_t *edx)
+{
+	return __get_cpuid_count(leaf, subleaf, eax, ebx, ecx, edx);
+}
+
+#pragma GCC diagnostic ignored "-Wunknown-pragmas"
+#pragma GCC push_options
+#pragma GCC target("xsave")
+#pragma clang attribute push (__attribute__((target("xsave"))), apply_to=function)
+
+// xgetbv reads the contents of an XCR (Extended Control Register)
+// specified in the ECX register into registers EDX:EAX.
+// Currently, the only supported value for XCR is 0.
+void
+gccgoXgetbv(uint32_t *eax, uint32_t *edx)
+{
+	uint64_t v = _xgetbv(0);
+	*eax = v & 0xffffffff;
+	*edx = v >> 32;
+}
+
+#pragma clang attribute pop
+#pragma GCC pop_options
diff --git a/vendor/golang.org/x/sys/cpu/cpu_gccgo_x86.go b/vendor/golang.org/x/sys/cpu/cpu_gccgo_x86.go
new file mode 100644
index 000000000..99c60fe9f
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_gccgo_x86.go
@@ -0,0 +1,31 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (386 || amd64 || amd64p32) && gccgo
+
+package cpu
+
+//extern gccgoGetCpuidCount
+func gccgoGetCpuidCount(eaxArg, ecxArg uint32, eax, ebx, ecx, edx *uint32)
+
+func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32) {
+	var a, b, c, d uint32
+	gccgoGetCpuidCount(eaxArg, ecxArg, &a, &b, &c, &d)
+	return a, b, c, d
+}
+
+//extern gccgoXgetbv
+func gccgoXgetbv(eax, edx *uint32)
+
+func xgetbv() (eax, edx uint32) {
+	var a, d uint32
+	gccgoXgetbv(&a, &d)
+	return a, d
+}
+
+// gccgo doesn't build on Darwin, per:
+// https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/gcc.rb#L76
+func darwinSupportsAVX512() bool {
+	return false
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux.go b/vendor/golang.org/x/sys/cpu/cpu_linux.go
new file mode 100644
index 000000000..743eb5435
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux.go
@@ -0,0 +1,15 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !386 && !amd64 && !amd64p32 && !arm64
+
+package cpu
+
+func archInit() {
+	if err := readHWCAP(); err != nil {
+		return
+	}
+	doinit()
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_arm.go b/vendor/golang.org/x/sys/cpu/cpu_linux_arm.go
new file mode 100644
index 000000000..2057006dc
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux_arm.go
@@ -0,0 +1,39 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+func doinit() {
+	ARM.HasSWP = isSet(hwCap, hwcap_SWP)
+	ARM.HasHALF = isSet(hwCap, hwcap_HALF)
+	ARM.HasTHUMB = isSet(hwCap, hwcap_THUMB)
+	ARM.Has26BIT = isSet(hwCap, hwcap_26BIT)
+	ARM.HasFASTMUL = isSet(hwCap, hwcap_FAST_MULT)
+	ARM.HasFPA = isSet(hwCap, hwcap_FPA)
+	ARM.HasVFP = isSet(hwCap, hwcap_VFP)
+	ARM.HasEDSP = isSet(hwCap, hwcap_EDSP)
+	ARM.HasJAVA = isSet(hwCap, hwcap_JAVA)
+	ARM.HasIWMMXT = isSet(hwCap, hwcap_IWMMXT)
+	ARM.HasCRUNCH = isSet(hwCap, hwcap_CRUNCH)
+	ARM.HasTHUMBEE = isSet(hwCap, hwcap_THUMBEE)
+	ARM.HasNEON = isSet(hwCap, hwcap_NEON)
+	ARM.HasVFPv3 = isSet(hwCap, hwcap_VFPv3)
+	ARM.HasVFPv3D16 = isSet(hwCap, hwcap_VFPv3D16)
+	ARM.HasTLS = isSet(hwCap, hwcap_TLS)
+	ARM.HasVFPv4 = isSet(hwCap, hwcap_VFPv4)
+	ARM.HasIDIVA = isSet(hwCap, hwcap_IDIVA)
+	ARM.HasIDIVT = isSet(hwCap, hwcap_IDIVT)
+	ARM.HasVFPD32 = isSet(hwCap, hwcap_VFPD32)
+	ARM.HasLPAE = isSet(hwCap, hwcap_LPAE)
+	ARM.HasEVTSTRM = isSet(hwCap, hwcap_EVTSTRM)
+	ARM.HasAES = isSet(hwCap2, hwcap2_AES)
+	ARM.HasPMULL = isSet(hwCap2, hwcap2_PMULL)
+	ARM.HasSHA1 = isSet(hwCap2, hwcap2_SHA1)
+	ARM.HasSHA2 = isSet(hwCap2, hwcap2_SHA2)
+	ARM.HasCRC32 = isSet(hwCap2, hwcap2_CRC32)
+}
+
+func isSet(hwc uint, value uint) bool {
+	return hwc&value != 0
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go
new file mode 100644
index 000000000..3d386d0fc
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go
@@ -0,0 +1,116 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"strings"
+	"syscall"
+)
+
+// HWCAP/HWCAP2 bits. These are exposed by Linux.
+const (
+	hwcap_FP       = 1 << 0
+	hwcap_ASIMD    = 1 << 1
+	hwcap_EVTSTRM  = 1 << 2
+	hwcap_AES      = 1 << 3
+	hwcap_PMULL    = 1 << 4
+	hwcap_SHA1     = 1 << 5
+	hwcap_SHA2     = 1 << 6
+	hwcap_CRC32    = 1 << 7
+	hwcap_ATOMICS  = 1 << 8
+	hwcap_FPHP     = 1 << 9
+	hwcap_ASIMDHP  = 1 << 10
+	hwcap_CPUID    = 1 << 11
+	hwcap_ASIMDRDM = 1 << 12
+	hwcap_JSCVT    = 1 << 13
+	hwcap_FCMA     = 1 << 14
+	hwcap_LRCPC    = 1 << 15
+	hwcap_DCPOP    = 1 << 16
+	hwcap_SHA3     = 1 << 17
+	hwcap_SM3      = 1 << 18
+	hwcap_SM4      = 1 << 19
+	hwcap_ASIMDDP  = 1 << 20
+	hwcap_SHA512   = 1 << 21
+	hwcap_SVE      = 1 << 22
+	hwcap_ASIMDFHM = 1 << 23
+
+	hwcap2_SVE2 = 1 << 1
+)
+
+// linuxKernelCanEmulateCPUID reports whether we're running
+// on Linux 4.11+. Ideally we'd like to ask the question about
+// whether the current kernel contains
+// https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=77c97b4ee21290f5f083173d957843b615abbff2
+// but the version number will have to do.
+func linuxKernelCanEmulateCPUID() bool {
+	var un syscall.Utsname
+	syscall.Uname(&un)
+	var sb strings.Builder
+	for _, b := range un.Release[:] {
+		if b == 0 {
+			break
+		}
+		sb.WriteByte(byte(b))
+	}
+	major, minor, _, ok := parseRelease(sb.String())
+	return ok && (major > 4 || major == 4 && minor >= 11)
+}
+
+func doinit() {
+	if err := readHWCAP(); err != nil {
+		// We failed to read /proc/self/auxv. This can happen if the binary has
+		// been given extra capabilities(7) with /bin/setcap.
+		//
+		// When this happens, we have two options. If the Linux kernel is new
+		// enough (4.11+), we can read the arm64 registers directly which'll
+		// trap into the kernel and then return back to userspace.
+		//
+		// But on older kernels, such as Linux 4.4.180 as used on many Synology
+		// devices, calling readARM64Registers (specifically getisar0) will
+		// cause a SIGILL and we'll die. So for older kernels, parse /proc/cpuinfo
+		// instead.
+		//
+		// See golang/go#57336.
+		if linuxKernelCanEmulateCPUID() {
+			readARM64Registers()
+		} else {
+			readLinuxProcCPUInfo()
+		}
+		return
+	}
+
+	// HWCAP feature bits
+	ARM64.HasFP = isSet(hwCap, hwcap_FP)
+	ARM64.HasASIMD = isSet(hwCap, hwcap_ASIMD)
+	ARM64.HasEVTSTRM = isSet(hwCap, hwcap_EVTSTRM)
+	ARM64.HasAES = isSet(hwCap, hwcap_AES)
+	ARM64.HasPMULL = isSet(hwCap, hwcap_PMULL)
+	ARM64.HasSHA1 = isSet(hwCap, hwcap_SHA1)
+	ARM64.HasSHA2 = isSet(hwCap, hwcap_SHA2)
+	ARM64.HasCRC32 = isSet(hwCap, hwcap_CRC32)
+	ARM64.HasATOMICS = isSet(hwCap, hwcap_ATOMICS)
+	ARM64.HasFPHP = isSet(hwCap, hwcap_FPHP)
+	ARM64.HasASIMDHP = isSet(hwCap, hwcap_ASIMDHP)
+	ARM64.HasCPUID = isSet(hwCap, hwcap_CPUID)
+	ARM64.HasASIMDRDM = isSet(hwCap, hwcap_ASIMDRDM)
+	ARM64.HasJSCVT = isSet(hwCap, hwcap_JSCVT)
+	ARM64.HasFCMA = isSet(hwCap, hwcap_FCMA)
+	ARM64.HasLRCPC = isSet(hwCap, hwcap_LRCPC)
+	ARM64.HasDCPOP = isSet(hwCap, hwcap_DCPOP)
+	ARM64.HasSHA3 = isSet(hwCap, hwcap_SHA3)
+	ARM64.HasSM3 = isSet(hwCap, hwcap_SM3)
+	ARM64.HasSM4 = isSet(hwCap, hwcap_SM4)
+	ARM64.HasASIMDDP = isSet(hwCap, hwcap_ASIMDDP)
+	ARM64.HasSHA512 = isSet(hwCap, hwcap_SHA512)
+	ARM64.HasSVE = isSet(hwCap, hwcap_SVE)
+	ARM64.HasASIMDFHM = isSet(hwCap, hwcap_ASIMDFHM)
+
+	// HWCAP2 feature bits
+	ARM64.HasSVE2 = isSet(hwCap2, hwcap2_SVE2)
+}
+
+func isSet(hwc uint, value uint) bool {
+	return hwc&value != 0
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_mips64x.go b/vendor/golang.org/x/sys/cpu/cpu_linux_mips64x.go
new file mode 100644
index 000000000..4686c1d54
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux_mips64x.go
@@ -0,0 +1,22 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && (mips64 || mips64le)
+
+package cpu
+
+// HWCAP bits. These are exposed by the Linux kernel 5.4.
+const (
+	// CPU features
+	hwcap_MIPS_MSA = 1 << 1
+)
+
+func doinit() {
+	// HWCAP feature bits
+	MIPS64X.HasMSA = isSet(hwCap, hwcap_MIPS_MSA)
+}
+
+func isSet(hwc uint, value uint) bool {
+	return hwc&value != 0
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_noinit.go b/vendor/golang.org/x/sys/cpu/cpu_linux_noinit.go
new file mode 100644
index 000000000..cd63e7335
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux_noinit.go
@@ -0,0 +1,9 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && !arm && !arm64 && !mips64 && !mips64le && !ppc64 && !ppc64le && !s390x
+
+package cpu
+
+func doinit() {}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_ppc64x.go b/vendor/golang.org/x/sys/cpu/cpu_linux_ppc64x.go
new file mode 100644
index 000000000..197188e67
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux_ppc64x.go
@@ -0,0 +1,30 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && (ppc64 || ppc64le)
+
+package cpu
+
+// HWCAP/HWCAP2 bits. These are exposed by the kernel.
+const (
+	// ISA Level
+	_PPC_FEATURE2_ARCH_2_07 = 0x80000000
+	_PPC_FEATURE2_ARCH_3_00 = 0x00800000
+
+	// CPU features
+	_PPC_FEATURE2_DARN = 0x00200000
+	_PPC_FEATURE2_SCV  = 0x00100000
+)
+
+func doinit() {
+	// HWCAP2 feature bits
+	PPC64.IsPOWER8 = isSet(hwCap2, _PPC_FEATURE2_ARCH_2_07)
+	PPC64.IsPOWER9 = isSet(hwCap2, _PPC_FEATURE2_ARCH_3_00)
+	PPC64.HasDARN = isSet(hwCap2, _PPC_FEATURE2_DARN)
+	PPC64.HasSCV = isSet(hwCap2, _PPC_FEATURE2_SCV)
+}
+
+func isSet(hwc uint, value uint) bool {
+	return hwc&value != 0
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_s390x.go b/vendor/golang.org/x/sys/cpu/cpu_linux_s390x.go
new file mode 100644
index 000000000..1517ac61d
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_linux_s390x.go
@@ -0,0 +1,40 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+const (
+	// bit mask values from /usr/include/bits/hwcap.h
+	hwcap_ZARCH  = 2
+	hwcap_STFLE  = 4
+	hwcap_MSA    = 8
+	hwcap_LDISP  = 16
+	hwcap_EIMM   = 32
+	hwcap_DFP    = 64
+	hwcap_ETF3EH = 256
+	hwcap_VX     = 2048
+	hwcap_VXE    = 8192
+)
+
+func initS390Xbase() {
+	// test HWCAP bit vector
+	has := func(featureMask uint) bool {
+		return hwCap&featureMask == featureMask
+	}
+
+	// mandatory
+	S390X.HasZARCH = has(hwcap_ZARCH)
+
+	// optional
+	S390X.HasSTFLE = has(hwcap_STFLE)
+	S390X.HasLDISP = has(hwcap_LDISP)
+	S390X.HasEIMM = has(hwcap_EIMM)
+	S390X.HasETF3EH = has(hwcap_ETF3EH)
+	S390X.HasDFP = has(hwcap_DFP)
+	S390X.HasMSA = has(hwcap_MSA)
+	S390X.HasVX = has(hwcap_VX)
+	if S390X.HasVX {
+		S390X.HasVXE = has(hwcap_VXE)
+	}
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_loong64.go b/vendor/golang.org/x/sys/cpu/cpu_loong64.go
new file mode 100644
index 000000000..558635850
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_loong64.go
@@ -0,0 +1,12 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build loong64
+
+package cpu
+
+const cacheLineSize = 64
+
+func initOptions() {
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_mips64x.go b/vendor/golang.org/x/sys/cpu/cpu_mips64x.go
new file mode 100644
index 000000000..fedb00cc4
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_mips64x.go
@@ -0,0 +1,15 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips64 || mips64le
+
+package cpu
+
+const cacheLineSize = 32
+
+func initOptions() {
+	options = []option{
+		{Name: "msa", Feature: &MIPS64X.HasMSA},
+	}
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_mipsx.go b/vendor/golang.org/x/sys/cpu/cpu_mipsx.go
new file mode 100644
index 000000000..ffb4ec7eb
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_mipsx.go
@@ -0,0 +1,11 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips || mipsle
+
+package cpu
+
+const cacheLineSize = 32
+
+func initOptions() {}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_netbsd_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_netbsd_arm64.go
new file mode 100644
index 000000000..ebfb3fc8e
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_netbsd_arm64.go
@@ -0,0 +1,173 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// Minimal copy of functionality from x/sys/unix so the cpu package can call
+// sysctl without depending on x/sys/unix.
+
+const (
+	_CTL_QUERY = -2
+
+	_SYSCTL_VERS_1 = 0x1000000
+)
+
+var _zero uintptr
+
+func sysctl(mib []int32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
+	var _p0 unsafe.Pointer
+	if len(mib) > 0 {
+		_p0 = unsafe.Pointer(&mib[0])
+	} else {
+		_p0 = unsafe.Pointer(&_zero)
+	}
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS___SYSCTL,
+		uintptr(_p0),
+		uintptr(len(mib)),
+		uintptr(unsafe.Pointer(old)),
+		uintptr(unsafe.Pointer(oldlen)),
+		uintptr(unsafe.Pointer(new)),
+		uintptr(newlen))
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+type sysctlNode struct {
+	Flags          uint32
+	Num            int32
+	Name           [32]int8
+	Ver            uint32
+	__rsvd         uint32
+	Un             [16]byte
+	_sysctl_size   [8]byte
+	_sysctl_func   [8]byte
+	_sysctl_parent [8]byte
+	_sysctl_desc   [8]byte
+}
+
+func sysctlNodes(mib []int32) ([]sysctlNode, error) {
+	var olen uintptr
+
+	// Get a list of all sysctl nodes below the given MIB by performing
+	// a sysctl for the given MIB with CTL_QUERY appended.
+	mib = append(mib, _CTL_QUERY)
+	qnode := sysctlNode{Flags: _SYSCTL_VERS_1}
+	qp := (*byte)(unsafe.Pointer(&qnode))
+	sz := unsafe.Sizeof(qnode)
+	if err := sysctl(mib, nil, &olen, qp, sz); err != nil {
+		return nil, err
+	}
+
+	// Now that we know the size, get the actual nodes.
+	nodes := make([]sysctlNode, olen/sz)
+	np := (*byte)(unsafe.Pointer(&nodes[0]))
+	if err := sysctl(mib, np, &olen, qp, sz); err != nil {
+		return nil, err
+	}
+
+	return nodes, nil
+}
+
+func nametomib(name string) ([]int32, error) {
+	// Split name into components.
+	var parts []string
+	last := 0
+	for i := 0; i < len(name); i++ {
+		if name[i] == '.' {
+			parts = append(parts, name[last:i])
+			last = i + 1
+		}
+	}
+	parts = append(parts, name[last:])
+
+	mib := []int32{}
+	// Discover the nodes and construct the MIB OID.
+	for partno, part := range parts {
+		nodes, err := sysctlNodes(mib)
+		if err != nil {
+			return nil, err
+		}
+		for _, node := range nodes {
+			n := make([]byte, 0)
+			for i := range node.Name {
+				if node.Name[i] != 0 {
+					n = append(n, byte(node.Name[i]))
+				}
+			}
+			if string(n) == part {
+				mib = append(mib, int32(node.Num))
+				break
+			}
+		}
+		if len(mib) != partno+1 {
+			return nil, err
+		}
+	}
+
+	return mib, nil
+}
+
+// aarch64SysctlCPUID is struct aarch64_sysctl_cpu_id from NetBSD's <aarch64/armreg.h>
+type aarch64SysctlCPUID struct {
+	midr      uint64 /* Main ID Register */
+	revidr    uint64 /* Revision ID Register */
+	mpidr     uint64 /* Multiprocessor Affinity Register */
+	aa64dfr0  uint64 /* A64 Debug Feature Register 0 */
+	aa64dfr1  uint64 /* A64 Debug Feature Register 1 */
+	aa64isar0 uint64 /* A64 Instruction Set Attribute Register 0 */
+	aa64isar1 uint64 /* A64 Instruction Set Attribute Register 1 */
+	aa64mmfr0 uint64 /* A64 Memory Model Feature Register 0 */
+	aa64mmfr1 uint64 /* A64 Memory Model Feature Register 1 */
+	aa64mmfr2 uint64 /* A64 Memory Model Feature Register 2 */
+	aa64pfr0  uint64 /* A64 Processor Feature Register 0 */
+	aa64pfr1  uint64 /* A64 Processor Feature Register 1 */
+	aa64zfr0  uint64 /* A64 SVE Feature ID Register 0 */
+	mvfr0     uint32 /* Media and VFP Feature Register 0 */
+	mvfr1     uint32 /* Media and VFP Feature Register 1 */
+	mvfr2     uint32 /* Media and VFP Feature Register 2 */
+	pad       uint32
+	clidr     uint64 /* Cache Level ID Register */
+	ctr       uint64 /* Cache Type Register */
+}
+
+func sysctlCPUID(name string) (*aarch64SysctlCPUID, error) {
+	mib, err := nametomib(name)
+	if err != nil {
+		return nil, err
+	}
+
+	out := aarch64SysctlCPUID{}
+	n := unsafe.Sizeof(out)
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS___SYSCTL,
+		uintptr(unsafe.Pointer(&mib[0])),
+		uintptr(len(mib)),
+		uintptr(unsafe.Pointer(&out)),
+		uintptr(unsafe.Pointer(&n)),
+		uintptr(0),
+		uintptr(0))
+	if errno != 0 {
+		return nil, errno
+	}
+	return &out, nil
+}
+
+func doinit() {
+	cpuid, err := sysctlCPUID("machdep.cpu0.cpu_id")
+	if err != nil {
+		setMinimalFeatures()
+		return
+	}
+	parseARM64SystemRegisters(cpuid.aa64isar0, cpuid.aa64isar1, cpuid.aa64pfr0)
+
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_openbsd_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_openbsd_arm64.go
new file mode 100644
index 000000000..85b64d5cc
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_openbsd_arm64.go
@@ -0,0 +1,65 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// Minimal copy of functionality from x/sys/unix so the cpu package can call
+// sysctl without depending on x/sys/unix.
+
+const (
+	// From OpenBSD's sys/sysctl.h.
+	_CTL_MACHDEP = 7
+
+	// From OpenBSD's machine/cpu.h.
+	_CPU_ID_AA64ISAR0 = 2
+	_CPU_ID_AA64ISAR1 = 3
+)
+
+// Implemented in the runtime package (runtime/sys_openbsd3.go)
+func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+//go:linkname syscall_syscall6 syscall.syscall6
+
+func sysctl(mib []uint32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
+	_, _, errno := syscall_syscall6(libc_sysctl_trampoline_addr, uintptr(unsafe.Pointer(&mib[0])), uintptr(len(mib)), uintptr(unsafe.Pointer(old)), uintptr(unsafe.Pointer(oldlen)), uintptr(unsafe.Pointer(new)), uintptr(newlen))
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+var libc_sysctl_trampoline_addr uintptr
+
+//go:cgo_import_dynamic libc_sysctl sysctl "libc.so"
+
+func sysctlUint64(mib []uint32) (uint64, bool) {
+	var out uint64
+	nout := unsafe.Sizeof(out)
+	if err := sysctl(mib, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0); err != nil {
+		return 0, false
+	}
+	return out, true
+}
+
+func doinit() {
+	setMinimalFeatures()
+
+	// Get ID_AA64ISAR0 and ID_AA64ISAR1 from sysctl.
+	isar0, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR0})
+	if !ok {
+		return
+	}
+	isar1, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR1})
+	if !ok {
+		return
+	}
+	parseARM64SystemRegisters(isar0, isar1, 0)
+
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_openbsd_arm64.s b/vendor/golang.org/x/sys/cpu/cpu_openbsd_arm64.s
new file mode 100644
index 000000000..054ba05d6
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_openbsd_arm64.s
@@ -0,0 +1,11 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+TEXT libc_sysctl_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	libc_sysctl(SB)
+
+GLOBL	·libc_sysctl_trampoline_addr(SB), RODATA, $8
+DATA	·libc_sysctl_trampoline_addr(SB)/8, $libc_sysctl_trampoline<>(SB)
diff --git a/vendor/golang.org/x/sys/cpu/cpu_other_arm.go b/vendor/golang.org/x/sys/cpu/cpu_other_arm.go
new file mode 100644
index 000000000..e9ecf2a45
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_other_arm.go
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !linux && arm
+
+package cpu
+
+func archInit() {}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_other_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_other_arm64.go
new file mode 100644
index 000000000..5341e7f88
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_other_arm64.go
@@ -0,0 +1,9 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !linux && !netbsd && !openbsd && arm64
+
+package cpu
+
+func doinit() {}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_other_mips64x.go b/vendor/golang.org/x/sys/cpu/cpu_other_mips64x.go
new file mode 100644
index 000000000..5f8f2419a
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_other_mips64x.go
@@ -0,0 +1,11 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !linux && (mips64 || mips64le)
+
+package cpu
+
+func archInit() {
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_other_ppc64x.go b/vendor/golang.org/x/sys/cpu/cpu_other_ppc64x.go
new file mode 100644
index 000000000..89608fba2
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_other_ppc64x.go
@@ -0,0 +1,12 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !aix && !linux && (ppc64 || ppc64le)
+
+package cpu
+
+func archInit() {
+	PPC64.IsPOWER8 = true
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_other_riscv64.go b/vendor/golang.org/x/sys/cpu/cpu_other_riscv64.go
new file mode 100644
index 000000000..5ab87808f
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_other_riscv64.go
@@ -0,0 +1,11 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !linux && riscv64
+
+package cpu
+
+func archInit() {
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_ppc64x.go b/vendor/golang.org/x/sys/cpu/cpu_ppc64x.go
new file mode 100644
index 000000000..c14f12b14
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_ppc64x.go
@@ -0,0 +1,16 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ppc64 || ppc64le
+
+package cpu
+
+const cacheLineSize = 128
+
+func initOptions() {
+	options = []option{
+		{Name: "darn", Feature: &PPC64.HasDARN},
+		{Name: "scv", Feature: &PPC64.HasSCV},
+	}
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_riscv64.go b/vendor/golang.org/x/sys/cpu/cpu_riscv64.go
new file mode 100644
index 000000000..7f0c79c00
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_riscv64.go
@@ -0,0 +1,11 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build riscv64
+
+package cpu
+
+const cacheLineSize = 64
+
+func initOptions() {}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_s390x.go b/vendor/golang.org/x/sys/cpu/cpu_s390x.go
new file mode 100644
index 000000000..5881b8833
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_s390x.go
@@ -0,0 +1,172 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+const cacheLineSize = 256
+
+func initOptions() {
+	options = []option{
+		{Name: "zarch", Feature: &S390X.HasZARCH, Required: true},
+		{Name: "stfle", Feature: &S390X.HasSTFLE, Required: true},
+		{Name: "ldisp", Feature: &S390X.HasLDISP, Required: true},
+		{Name: "eimm", Feature: &S390X.HasEIMM, Required: true},
+		{Name: "dfp", Feature: &S390X.HasDFP},
+		{Name: "etf3eh", Feature: &S390X.HasETF3EH},
+		{Name: "msa", Feature: &S390X.HasMSA},
+		{Name: "aes", Feature: &S390X.HasAES},
+		{Name: "aescbc", Feature: &S390X.HasAESCBC},
+		{Name: "aesctr", Feature: &S390X.HasAESCTR},
+		{Name: "aesgcm", Feature: &S390X.HasAESGCM},
+		{Name: "ghash", Feature: &S390X.HasGHASH},
+		{Name: "sha1", Feature: &S390X.HasSHA1},
+		{Name: "sha256", Feature: &S390X.HasSHA256},
+		{Name: "sha3", Feature: &S390X.HasSHA3},
+		{Name: "sha512", Feature: &S390X.HasSHA512},
+		{Name: "vx", Feature: &S390X.HasVX},
+		{Name: "vxe", Feature: &S390X.HasVXE},
+	}
+}
+
+// bitIsSet reports whether the bit at index is set. The bit index
+// is in big endian order, so bit index 0 is the leftmost bit.
+func bitIsSet(bits []uint64, index uint) bool {
+	return bits[index/64]&((1<<63)>>(index%64)) != 0
+}
+
+// facility is a bit index for the named facility.
+type facility uint8
+
+const (
+	// mandatory facilities
+	zarch  facility = 1  // z architecture mode is active
+	stflef facility = 7  // store-facility-list-extended
+	ldisp  facility = 18 // long-displacement
+	eimm   facility = 21 // extended-immediate
+
+	// miscellaneous facilities
+	dfp    facility = 42 // decimal-floating-point
+	etf3eh facility = 30 // extended-translation 3 enhancement
+
+	// cryptography facilities
+	msa  facility = 17  // message-security-assist
+	msa3 facility = 76  // message-security-assist extension 3
+	msa4 facility = 77  // message-security-assist extension 4
+	msa5 facility = 57  // message-security-assist extension 5
+	msa8 facility = 146 // message-security-assist extension 8
+	msa9 facility = 155 // message-security-assist extension 9
+
+	// vector facilities
+	vx   facility = 129 // vector facility
+	vxe  facility = 135 // vector-enhancements 1
+	vxe2 facility = 148 // vector-enhancements 2
+)
+
+// facilityList contains the result of an STFLE call.
+// Bits are numbered in big endian order so the
+// leftmost bit (the MSB) is at index 0.
+type facilityList struct {
+	bits [4]uint64
+}
+
+// Has reports whether the given facilities are present.
+func (s *facilityList) Has(fs ...facility) bool {
+	if len(fs) == 0 {
+		panic("no facility bits provided")
+	}
+	for _, f := range fs {
+		if !bitIsSet(s.bits[:], uint(f)) {
+			return false
+		}
+	}
+	return true
+}
+
+// function is the code for the named cryptographic function.
+type function uint8
+
+const (
+	// KM{,A,C,CTR} function codes
+	aes128 function = 18 // AES-128
+	aes192 function = 19 // AES-192
+	aes256 function = 20 // AES-256
+
+	// K{I,L}MD function codes
+	sha1     function = 1  // SHA-1
+	sha256   function = 2  // SHA-256
+	sha512   function = 3  // SHA-512
+	sha3_224 function = 32 // SHA3-224
+	sha3_256 function = 33 // SHA3-256
+	sha3_384 function = 34 // SHA3-384
+	sha3_512 function = 35 // SHA3-512
+	shake128 function = 36 // SHAKE-128
+	shake256 function = 37 // SHAKE-256
+
+	// KLMD function codes
+	ghash function = 65 // GHASH
+)
+
+// queryResult contains the result of a Query function
+// call. Bits are numbered in big endian order so the
+// leftmost bit (the MSB) is at index 0.
+type queryResult struct {
+	bits [2]uint64
+}
+
+// Has reports whether the given functions are present.
+func (q *queryResult) Has(fns ...function) bool {
+	if len(fns) == 0 {
+		panic("no function codes provided")
+	}
+	for _, f := range fns {
+		if !bitIsSet(q.bits[:], uint(f)) {
+			return false
+		}
+	}
+	return true
+}
+
+func doinit() {
+	initS390Xbase()
+
+	// We need implementations of stfle, km and so on
+	// to detect cryptographic features.
+	if !haveAsmFunctions() {
+		return
+	}
+
+	// optional cryptographic functions
+	if S390X.HasMSA {
+		aes := []function{aes128, aes192, aes256}
+
+		// cipher message
+		km, kmc := kmQuery(), kmcQuery()
+		S390X.HasAES = km.Has(aes...)
+		S390X.HasAESCBC = kmc.Has(aes...)
+		if S390X.HasSTFLE {
+			facilities := stfle()
+			if facilities.Has(msa4) {
+				kmctr := kmctrQuery()
+				S390X.HasAESCTR = kmctr.Has(aes...)
+			}
+			if facilities.Has(msa8) {
+				kma := kmaQuery()
+				S390X.HasAESGCM = kma.Has(aes...)
+			}
+		}
+
+		// compute message digest
+		kimd := kimdQuery() // intermediate (no padding)
+		klmd := klmdQuery() // last (padding)
+		S390X.HasSHA1 = kimd.Has(sha1) && klmd.Has(sha1)
+		S390X.HasSHA256 = kimd.Has(sha256) && klmd.Has(sha256)
+		S390X.HasSHA512 = kimd.Has(sha512) && klmd.Has(sha512)
+		S390X.HasGHASH = kimd.Has(ghash) // KLMD-GHASH does not exist
+		sha3 := []function{
+			sha3_224, sha3_256, sha3_384, sha3_512,
+			shake128, shake256,
+		}
+		S390X.HasSHA3 = kimd.Has(sha3...) && klmd.Has(sha3...)
+	}
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_s390x.s b/vendor/golang.org/x/sys/cpu/cpu_s390x.s
new file mode 100644
index 000000000..1fb4b7013
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_s390x.s
@@ -0,0 +1,57 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gc
+
+#include "textflag.h"
+
+// func stfle() facilityList
+TEXT ·stfle(SB), NOSPLIT|NOFRAME, $0-32
+	MOVD $ret+0(FP), R1
+	MOVD $3, R0          // last doubleword index to store
+	XC   $32, (R1), (R1) // clear 4 doublewords (32 bytes)
+	WORD $0xb2b01000     // store facility list extended (STFLE)
+	RET
+
+// func kmQuery() queryResult
+TEXT ·kmQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KM-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xB92E0024    // cipher message (KM)
+	RET
+
+// func kmcQuery() queryResult
+TEXT ·kmcQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KMC-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xB92F0024    // cipher message with chaining (KMC)
+	RET
+
+// func kmctrQuery() queryResult
+TEXT ·kmctrQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KMCTR-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xB92D4024    // cipher message with counter (KMCTR)
+	RET
+
+// func kmaQuery() queryResult
+TEXT ·kmaQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KMA-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xb9296024    // cipher message with authentication (KMA)
+	RET
+
+// func kimdQuery() queryResult
+TEXT ·kimdQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KIMD-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xB93E0024    // compute intermediate message digest (KIMD)
+	RET
+
+// func klmdQuery() queryResult
+TEXT ·klmdQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KLMD-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xB93F0024    // compute last message digest (KLMD)
+	RET
diff --git a/vendor/golang.org/x/sys/cpu/cpu_wasm.go b/vendor/golang.org/x/sys/cpu/cpu_wasm.go
new file mode 100644
index 000000000..384787ea3
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_wasm.go
@@ -0,0 +1,17 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build wasm
+
+package cpu
+
+// We're compiling the cpu package for an unknown (software-abstracted) CPU.
+// Make CacheLinePad an empty struct and hope that the usual struct alignment
+// rules are good enough.
+
+const cacheLineSize = 0
+
+func initOptions() {}
+
+func archInit() {}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_x86.go b/vendor/golang.org/x/sys/cpu/cpu_x86.go
new file mode 100644
index 000000000..c29f5e4c5
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_x86.go
@@ -0,0 +1,151 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build 386 || amd64 || amd64p32
+
+package cpu
+
+import "runtime"
+
+const cacheLineSize = 64
+
+func initOptions() {
+	options = []option{
+		{Name: "adx", Feature: &X86.HasADX},
+		{Name: "aes", Feature: &X86.HasAES},
+		{Name: "avx", Feature: &X86.HasAVX},
+		{Name: "avx2", Feature: &X86.HasAVX2},
+		{Name: "avx512", Feature: &X86.HasAVX512},
+		{Name: "avx512f", Feature: &X86.HasAVX512F},
+		{Name: "avx512cd", Feature: &X86.HasAVX512CD},
+		{Name: "avx512er", Feature: &X86.HasAVX512ER},
+		{Name: "avx512pf", Feature: &X86.HasAVX512PF},
+		{Name: "avx512vl", Feature: &X86.HasAVX512VL},
+		{Name: "avx512bw", Feature: &X86.HasAVX512BW},
+		{Name: "avx512dq", Feature: &X86.HasAVX512DQ},
+		{Name: "avx512ifma", Feature: &X86.HasAVX512IFMA},
+		{Name: "avx512vbmi", Feature: &X86.HasAVX512VBMI},
+		{Name: "avx512vnniw", Feature: &X86.HasAVX5124VNNIW},
+		{Name: "avx5124fmaps", Feature: &X86.HasAVX5124FMAPS},
+		{Name: "avx512vpopcntdq", Feature: &X86.HasAVX512VPOPCNTDQ},
+		{Name: "avx512vpclmulqdq", Feature: &X86.HasAVX512VPCLMULQDQ},
+		{Name: "avx512vnni", Feature: &X86.HasAVX512VNNI},
+		{Name: "avx512gfni", Feature: &X86.HasAVX512GFNI},
+		{Name: "avx512vaes", Feature: &X86.HasAVX512VAES},
+		{Name: "avx512vbmi2", Feature: &X86.HasAVX512VBMI2},
+		{Name: "avx512bitalg", Feature: &X86.HasAVX512BITALG},
+		{Name: "avx512bf16", Feature: &X86.HasAVX512BF16},
+		{Name: "amxtile", Feature: &X86.HasAMXTile},
+		{Name: "amxint8", Feature: &X86.HasAMXInt8},
+		{Name: "amxbf16", Feature: &X86.HasAMXBF16},
+		{Name: "bmi1", Feature: &X86.HasBMI1},
+		{Name: "bmi2", Feature: &X86.HasBMI2},
+		{Name: "cx16", Feature: &X86.HasCX16},
+		{Name: "erms", Feature: &X86.HasERMS},
+		{Name: "fma", Feature: &X86.HasFMA},
+		{Name: "osxsave", Feature: &X86.HasOSXSAVE},
+		{Name: "pclmulqdq", Feature: &X86.HasPCLMULQDQ},
+		{Name: "popcnt", Feature: &X86.HasPOPCNT},
+		{Name: "rdrand", Feature: &X86.HasRDRAND},
+		{Name: "rdseed", Feature: &X86.HasRDSEED},
+		{Name: "sse3", Feature: &X86.HasSSE3},
+		{Name: "sse41", Feature: &X86.HasSSE41},
+		{Name: "sse42", Feature: &X86.HasSSE42},
+		{Name: "ssse3", Feature: &X86.HasSSSE3},
+
+		// These capabilities should always be enabled on amd64:
+		{Name: "sse2", Feature: &X86.HasSSE2, Required: runtime.GOARCH == "amd64"},
+	}
+}
+
+func archInit() {
+
+	Initialized = true
+
+	maxID, _, _, _ := cpuid(0, 0)
+
+	if maxID < 1 {
+		return
+	}
+
+	_, _, ecx1, edx1 := cpuid(1, 0)
+	X86.HasSSE2 = isSet(26, edx1)
+
+	X86.HasSSE3 = isSet(0, ecx1)
+	X86.HasPCLMULQDQ = isSet(1, ecx1)
+	X86.HasSSSE3 = isSet(9, ecx1)
+	X86.HasFMA = isSet(12, ecx1)
+	X86.HasCX16 = isSet(13, ecx1)
+	X86.HasSSE41 = isSet(19, ecx1)
+	X86.HasSSE42 = isSet(20, ecx1)
+	X86.HasPOPCNT = isSet(23, ecx1)
+	X86.HasAES = isSet(25, ecx1)
+	X86.HasOSXSAVE = isSet(27, ecx1)
+	X86.HasRDRAND = isSet(30, ecx1)
+
+	var osSupportsAVX, osSupportsAVX512 bool
+	// For XGETBV, OSXSAVE bit is required and sufficient.
+	if X86.HasOSXSAVE {
+		eax, _ := xgetbv()
+		// Check if XMM and YMM registers have OS support.
+		osSupportsAVX = isSet(1, eax) && isSet(2, eax)
+
+		if runtime.GOOS == "darwin" {
+			// Darwin doesn't save/restore AVX-512 mask registers correctly across signal handlers.
+			// Since users can't rely on mask register contents, let's not advertise AVX-512 support.
+			// See issue 49233.
+			osSupportsAVX512 = false
+		} else {
+			// Check if OPMASK and ZMM registers have OS support.
+			osSupportsAVX512 = osSupportsAVX && isSet(5, eax) && isSet(6, eax) && isSet(7, eax)
+		}
+	}
+
+	X86.HasAVX = isSet(28, ecx1) && osSupportsAVX
+
+	if maxID < 7 {
+		return
+	}
+
+	_, ebx7, ecx7, edx7 := cpuid(7, 0)
+	X86.HasBMI1 = isSet(3, ebx7)
+	X86.HasAVX2 = isSet(5, ebx7) && osSupportsAVX
+	X86.HasBMI2 = isSet(8, ebx7)
+	X86.HasERMS = isSet(9, ebx7)
+	X86.HasRDSEED = isSet(18, ebx7)
+	X86.HasADX = isSet(19, ebx7)
+
+	X86.HasAVX512 = isSet(16, ebx7) && osSupportsAVX512 // Because avx-512 foundation is the core required extension
+	if X86.HasAVX512 {
+		X86.HasAVX512F = true
+		X86.HasAVX512CD = isSet(28, ebx7)
+		X86.HasAVX512ER = isSet(27, ebx7)
+		X86.HasAVX512PF = isSet(26, ebx7)
+		X86.HasAVX512VL = isSet(31, ebx7)
+		X86.HasAVX512BW = isSet(30, ebx7)
+		X86.HasAVX512DQ = isSet(17, ebx7)
+		X86.HasAVX512IFMA = isSet(21, ebx7)
+		X86.HasAVX512VBMI = isSet(1, ecx7)
+		X86.HasAVX5124VNNIW = isSet(2, edx7)
+		X86.HasAVX5124FMAPS = isSet(3, edx7)
+		X86.HasAVX512VPOPCNTDQ = isSet(14, ecx7)
+		X86.HasAVX512VPCLMULQDQ = isSet(10, ecx7)
+		X86.HasAVX512VNNI = isSet(11, ecx7)
+		X86.HasAVX512GFNI = isSet(8, ecx7)
+		X86.HasAVX512VAES = isSet(9, ecx7)
+		X86.HasAVX512VBMI2 = isSet(6, ecx7)
+		X86.HasAVX512BITALG = isSet(12, ecx7)
+
+		eax71, _, _, _ := cpuid(7, 1)
+		X86.HasAVX512BF16 = isSet(5, eax71)
+	}
+
+	X86.HasAMXTile = isSet(24, edx7)
+	X86.HasAMXInt8 = isSet(25, edx7)
+	X86.HasAMXBF16 = isSet(22, edx7)
+}
+
+func isSet(bitpos uint, value uint32) bool {
+	return value&(1<<bitpos) != 0
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_x86.s b/vendor/golang.org/x/sys/cpu/cpu_x86.s
new file mode 100644
index 000000000..7d7ba33ef
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_x86.s
@@ -0,0 +1,26 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (386 || amd64 || amd64p32) && gc
+
+#include "textflag.h"
+
+// func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
+TEXT ·cpuid(SB), NOSPLIT, $0-24
+	MOVL eaxArg+0(FP), AX
+	MOVL ecxArg+4(FP), CX
+	CPUID
+	MOVL AX, eax+8(FP)
+	MOVL BX, ebx+12(FP)
+	MOVL CX, ecx+16(FP)
+	MOVL DX, edx+20(FP)
+	RET
+
+// func xgetbv() (eax, edx uint32)
+TEXT ·xgetbv(SB),NOSPLIT,$0-8
+	MOVL $0, CX
+	XGETBV
+	MOVL AX, eax+0(FP)
+	MOVL DX, edx+4(FP)
+	RET
diff --git a/vendor/golang.org/x/sys/cpu/cpu_zos.go b/vendor/golang.org/x/sys/cpu/cpu_zos.go
new file mode 100644
index 000000000..5f54683a2
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_zos.go
@@ -0,0 +1,10 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+func archInit() {
+	doinit()
+	Initialized = true
+}
diff --git a/vendor/golang.org/x/sys/cpu/cpu_zos_s390x.go b/vendor/golang.org/x/sys/cpu/cpu_zos_s390x.go
new file mode 100644
index 000000000..ccb1b708a
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/cpu_zos_s390x.go
@@ -0,0 +1,25 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+func initS390Xbase() {
+	// get the facilities list
+	facilities := stfle()
+
+	// mandatory
+	S390X.HasZARCH = facilities.Has(zarch)
+	S390X.HasSTFLE = facilities.Has(stflef)
+	S390X.HasLDISP = facilities.Has(ldisp)
+	S390X.HasEIMM = facilities.Has(eimm)
+
+	// optional
+	S390X.HasETF3EH = facilities.Has(etf3eh)
+	S390X.HasDFP = facilities.Has(dfp)
+	S390X.HasMSA = facilities.Has(msa)
+	S390X.HasVX = facilities.Has(vx)
+	if S390X.HasVX {
+		S390X.HasVXE = facilities.Has(vxe)
+	}
+}
diff --git a/vendor/golang.org/x/sys/cpu/endian_big.go b/vendor/golang.org/x/sys/cpu/endian_big.go
new file mode 100644
index 000000000..7fe04b0a1
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/endian_big.go
@@ -0,0 +1,10 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build armbe || arm64be || m68k || mips || mips64 || mips64p32 || ppc || ppc64 || s390 || s390x || shbe || sparc || sparc64
+
+package cpu
+
+// IsBigEndian records whether the GOARCH's byte order is big endian.
+const IsBigEndian = true
diff --git a/vendor/golang.org/x/sys/cpu/endian_little.go b/vendor/golang.org/x/sys/cpu/endian_little.go
new file mode 100644
index 000000000..48eccc4c7
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/endian_little.go
@@ -0,0 +1,10 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build 386 || amd64 || amd64p32 || alpha || arm || arm64 || loong64 || mipsle || mips64le || mips64p32le || nios2 || ppc64le || riscv || riscv64 || sh || wasm
+
+package cpu
+
+// IsBigEndian records whether the GOARCH's byte order is big endian.
+const IsBigEndian = false
diff --git a/vendor/golang.org/x/sys/cpu/hwcap_linux.go b/vendor/golang.org/x/sys/cpu/hwcap_linux.go
new file mode 100644
index 000000000..34e49f955
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/hwcap_linux.go
@@ -0,0 +1,71 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"os"
+)
+
+const (
+	_AT_HWCAP  = 16
+	_AT_HWCAP2 = 26
+
+	procAuxv = "/proc/self/auxv"
+
+	uintSize = int(32 << (^uint(0) >> 63))
+)
+
+// For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
+// These are initialized in cpu_$GOARCH.go
+// and should not be changed after they are initialized.
+var hwCap uint
+var hwCap2 uint
+
+func readHWCAP() error {
+	// For Go 1.21+, get auxv from the Go runtime.
+	if a := getAuxv(); len(a) > 0 {
+		for len(a) >= 2 {
+			tag, val := a[0], uint(a[1])
+			a = a[2:]
+			switch tag {
+			case _AT_HWCAP:
+				hwCap = val
+			case _AT_HWCAP2:
+				hwCap2 = val
+			}
+		}
+		return nil
+	}
+
+	buf, err := os.ReadFile(procAuxv)
+	if err != nil {
+		// e.g. on android /proc/self/auxv is not accessible, so silently
+		// ignore the error and leave Initialized = false. On some
+		// architectures (e.g. arm64) doinit() implements a fallback
+		// readout and will set Initialized = true again.
+		return err
+	}
+	bo := hostByteOrder()
+	for len(buf) >= 2*(uintSize/8) {
+		var tag, val uint
+		switch uintSize {
+		case 32:
+			tag = uint(bo.Uint32(buf[0:]))
+			val = uint(bo.Uint32(buf[4:]))
+			buf = buf[8:]
+		case 64:
+			tag = uint(bo.Uint64(buf[0:]))
+			val = uint(bo.Uint64(buf[8:]))
+			buf = buf[16:]
+		}
+		switch tag {
+		case _AT_HWCAP:
+			hwCap = val
+		case _AT_HWCAP2:
+			hwCap2 = val
+		}
+	}
+	return nil
+}
diff --git a/vendor/golang.org/x/sys/cpu/parse.go b/vendor/golang.org/x/sys/cpu/parse.go
new file mode 100644
index 000000000..762b63d68
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/parse.go
@@ -0,0 +1,43 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+import "strconv"
+
+// parseRelease parses a dot-separated version number. It follows the semver
+// syntax, but allows the minor and patch versions to be elided.
+//
+// This is a copy of the Go runtime's parseRelease from
+// https://golang.org/cl/209597.
+func parseRelease(rel string) (major, minor, patch int, ok bool) {
+	// Strip anything after a dash or plus.
+	for i := 0; i < len(rel); i++ {
+		if rel[i] == '-' || rel[i] == '+' {
+			rel = rel[:i]
+			break
+		}
+	}
+
+	next := func() (int, bool) {
+		for i := 0; i < len(rel); i++ {
+			if rel[i] == '.' {
+				ver, err := strconv.Atoi(rel[:i])
+				rel = rel[i+1:]
+				return ver, err == nil
+			}
+		}
+		ver, err := strconv.Atoi(rel)
+		rel = ""
+		return ver, err == nil
+	}
+	if major, ok = next(); !ok || rel == "" {
+		return
+	}
+	if minor, ok = next(); !ok || rel == "" {
+		return
+	}
+	patch, ok = next()
+	return
+}
diff --git a/vendor/golang.org/x/sys/cpu/proc_cpuinfo_linux.go b/vendor/golang.org/x/sys/cpu/proc_cpuinfo_linux.go
new file mode 100644
index 000000000..4cd64c704
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/proc_cpuinfo_linux.go
@@ -0,0 +1,53 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && arm64
+
+package cpu
+
+import (
+	"errors"
+	"io"
+	"os"
+	"strings"
+)
+
+func readLinuxProcCPUInfo() error {
+	f, err := os.Open("/proc/cpuinfo")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	var buf [1 << 10]byte // enough for first CPU
+	n, err := io.ReadFull(f, buf[:])
+	if err != nil && err != io.ErrUnexpectedEOF {
+		return err
+	}
+	in := string(buf[:n])
+	const features = "\nFeatures	: "
+	i := strings.Index(in, features)
+	if i == -1 {
+		return errors.New("no CPU features found")
+	}
+	in = in[i+len(features):]
+	if i := strings.Index(in, "\n"); i != -1 {
+		in = in[:i]
+	}
+	m := map[string]*bool{}
+
+	initOptions() // need it early here; it's harmless to call twice
+	for _, o := range options {
+		m[o.Name] = o.Feature
+	}
+	// The EVTSTRM field has alias "evstrm" in Go, but Linux calls it "evtstrm".
+	m["evtstrm"] = &ARM64.HasEVTSTRM
+
+	for _, f := range strings.Fields(in) {
+		if p, ok := m[f]; ok {
+			*p = true
+		}
+	}
+	return nil
+}
diff --git a/vendor/golang.org/x/sys/cpu/runtime_auxv.go b/vendor/golang.org/x/sys/cpu/runtime_auxv.go
new file mode 100644
index 000000000..5f92ac9a2
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/runtime_auxv.go
@@ -0,0 +1,16 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+// getAuxvFn is non-nil on Go 1.21+ (via runtime_auxv_go121.go init)
+// on platforms that use auxv.
+var getAuxvFn func() []uintptr
+
+func getAuxv() []uintptr {
+	if getAuxvFn == nil {
+		return nil
+	}
+	return getAuxvFn()
+}
diff --git a/vendor/golang.org/x/sys/cpu/runtime_auxv_go121.go b/vendor/golang.org/x/sys/cpu/runtime_auxv_go121.go
new file mode 100644
index 000000000..4c9788ea8
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/runtime_auxv_go121.go
@@ -0,0 +1,18 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.21
+
+package cpu
+
+import (
+	_ "unsafe" // for linkname
+)
+
+//go:linkname runtime_getAuxv runtime.getAuxv
+func runtime_getAuxv() []uintptr
+
+func init() {
+	getAuxvFn = runtime_getAuxv
+}
diff --git a/vendor/golang.org/x/sys/cpu/syscall_aix_gccgo.go b/vendor/golang.org/x/sys/cpu/syscall_aix_gccgo.go
new file mode 100644
index 000000000..1b9ccb091
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/syscall_aix_gccgo.go
@@ -0,0 +1,26 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Recreate a getsystemcfg syscall handler instead of
+// using the one provided by x/sys/unix to avoid having
+// the dependency between them. (See golang.org/issue/32102)
+// Moreover, this file will be used during the building of
+// gccgo's libgo and thus must not used a CGo method.
+
+//go:build aix && gccgo
+
+package cpu
+
+import (
+	"syscall"
+)
+
+//extern getsystemcfg
+func gccgoGetsystemcfg(label uint32) (r uint64)
+
+func callgetsystemcfg(label int) (r1 uintptr, e1 syscall.Errno) {
+	r1 = uintptr(gccgoGetsystemcfg(uint32(label)))
+	e1 = syscall.GetErrno()
+	return
+}
diff --git a/vendor/golang.org/x/sys/cpu/syscall_aix_ppc64_gc.go b/vendor/golang.org/x/sys/cpu/syscall_aix_ppc64_gc.go
new file mode 100644
index 000000000..e8b6cdbe9
--- /dev/null
+++ b/vendor/golang.org/x/sys/cpu/syscall_aix_ppc64_gc.go
@@ -0,0 +1,35 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Minimal copy of x/sys/unix so the cpu package can make a
+// system call on AIX without depending on x/sys/unix.
+// (See golang.org/issue/32102)
+
+//go:build aix && ppc64 && gc
+
+package cpu
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+//go:cgo_import_dynamic libc_getsystemcfg getsystemcfg "libc.a/shr_64.o"
+
+//go:linkname libc_getsystemcfg libc_getsystemcfg
+
+type syscallFunc uintptr
+
+var libc_getsystemcfg syscallFunc
+
+type errno = syscall.Errno
+
+// Implemented in runtime/syscall_aix.go.
+func rawSyscall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err errno)
+func syscall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err errno)
+
+func callgetsystemcfg(label int) (r1 uintptr, e1 errno) {
+	r1, _, e1 = syscall6(uintptr(unsafe.Pointer(&libc_getsystemcfg)), 1, uintptr(label), 0, 0, 0, 0, 0)
+	return
+}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index bb837f843..b9fa4eb5e 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -890,8 +890,15 @@ go4.org/errorutil
 ## explicit; go 1.18
 golang.org/x/crypto/bcrypt
 golang.org/x/crypto/blowfish
+golang.org/x/crypto/chacha20
+golang.org/x/crypto/curve25519
+golang.org/x/crypto/curve25519/internal/field
+golang.org/x/crypto/internal/alias
+golang.org/x/crypto/internal/poly1305
 golang.org/x/crypto/pbkdf2
 golang.org/x/crypto/scrypt
+golang.org/x/crypto/ssh
+golang.org/x/crypto/ssh/internal/bcrypt_pbkdf
 # golang.org/x/exp v0.0.0-20231127185646-65229373498e
 ## explicit; go 1.20
 golang.org/x/exp/constraints
@@ -920,6 +927,7 @@ golang.org/x/oauth2/internal
 golang.org/x/sync/errgroup
 # golang.org/x/sys v0.20.0
 ## explicit; go 1.18
+golang.org/x/sys/cpu
 golang.org/x/sys/plan9
 golang.org/x/sys/unix
 golang.org/x/sys/windows