From 236ef0871df13460bd3542930ece67c72e35e113 Mon Sep 17 00:00:00 2001
From: Steffen Jaeckel <s@jaeckel.eu>
Date: Tue, 10 Oct 2023 10:41:45 +0200
Subject: [PATCH] Add "Enter passphrase" support to `openssh-privkey`

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>
---
 demos/openssh-privkey.c | 73 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 66 insertions(+), 7 deletions(-)

diff --git a/demos/openssh-privkey.c b/demos/openssh-privkey.c
index 9d1f80b08..af88cdbfa 100644
--- a/demos/openssh-privkey.c
+++ b/demos/openssh-privkey.c
@@ -8,37 +8,95 @@
 
 #include <tomcrypt.h>
 #include <stdarg.h>
-
-static int verbose = 0;
+#include <termios.h>
 
 static void print_err(const char *fmt, ...)
 {
    va_list args;
 
-   if (!verbose) return;
-
    va_start(args, fmt);
    vfprintf(stderr, fmt, args);
+   va_end(args);
 }
 
 static void die_(int err, int line)
 {
-   verbose = 1;
    print_err("%3d: LTC sez %s\n", line, error_to_string(err));
    exit(EXIT_FAILURE);
 }
 
 #define die(i) do { die_(i, __LINE__); } while(0)
-#define DIE(s, ...) do { verbose = 1; print_err("%3d: " s "\n", __LINE__, ##__VA_ARGS__); exit(EXIT_FAILURE); } while(0)
+#define DIE(s, ...) do { print_err("%3d: " s "\n", __LINE__, ##__VA_ARGS__); exit(EXIT_FAILURE); } while(0)
+
+static char* getpassword(const char *prompt, size_t maxlen)
+{
+   char *wr, *end, *pass = XCALLOC(1, maxlen + 1);
+   struct termios tio;
+   tcflag_t c_lflag;
+   if (pass == NULL)
+      return NULL;
+   wr = pass;
+   end = pass + maxlen;
+
+   tcgetattr(0, &tio);
+   c_lflag = tio.c_lflag;
+   tio.c_lflag &= ~ECHO;
+   tcsetattr(0, TCSANOW, &tio);
+
+   printf("%s", prompt);
+   fflush(stdout);
+   while (pass < end) {
+      int c = getchar();
+      if (c == '\r' || c == '\n' || c == -1)
+         break;
+      *wr++ = c;
+   }
+   tio.c_lflag = c_lflag;
+   tcsetattr(0, TCSAFLUSH, &tio);
+   printf("\n");
+   return pass;
+}
 
 static int password_get(void **p, unsigned long *l, void *u)
 {
    (void)u;
-   *p = strdup("abc123");
+   *p = getpassword("Enter passphrase: ", 256);
    *l = strlen(*p);
    return 0;
 }
 
+static void print(ltc_pka_key *k)
+{
+   int err = CRYPT_OK;
+   unsigned char buf[256];
+   unsigned long lbuf = sizeof(buf);
+   char pubkey[256*4/3];
+   unsigned long lpubkey = sizeof(pubkey);
+   void *mpint = NULL;
+   switch (k->id) {
+      case LTC_PKA_ED25519:
+         ltc_mp.init(&mpint);
+         ltc_mp.unsigned_read(mpint, k->u.ed25519.pub, sizeof(k->u.ed25519.pub));
+         if ((err = ssh_encode_sequence_multi(buf, &lbuf,
+                                              LTC_SSHDATA_STRING, "ssh-ed25519", strlen("ssh-ed25519"),
+                                              LTC_SSHDATA_MPINT, mpint,
+                                              0, NULL)) != CRYPT_OK)
+            goto errout;
+         if ((err = base64_encode(buf, lbuf, pubkey, &lpubkey)) != CRYPT_OK)
+            goto errout;
+         printf("\rssh-ed25519 %s\n", pubkey);
+         break;
+      default:
+         print_err("Unsupported key type: %d\n", k->id);
+         break;
+   }
+errout:
+   if (mpint != NULL)
+      ltc_mp.deinit(mpint);
+   if (err != CRYPT_OK)
+      die(err);
+}
+
 int main(int argc, char **argv)
 {
    int err;
@@ -64,6 +122,7 @@ int main(int argc, char **argv)
    if ((err = pem_decode_openssh_filehandle(f, &k, &pw_ctx))) {
       die(err);
    }
+   print(&k);
    return EXIT_SUCCESS;
 }