Merge pull request DotBots#283 from aabadie/ota_crypto

OTAP: add basic support for crypto primitives (sha256 hash, ed25519 signature)

Makefile

@@ -7,6 +7,7 @@ SEGGER_DIR ?= /opt/segger
 BUILD_CONFIG ?= Debug
 BUILD_TARGET ?= dotbot-v1
 PROJECT_FILE ?= $(BUILD_TARGET).emProject
+BOOTLOADER ?= bootloader
 
 ifeq (nrf5340dk-app,$(BUILD_TARGET))
   PROJECTS ?= \
@@ -56,30 +57,30 @@ else ifeq (nrf5340dk-net,$(BUILD_TARGET))
     03app_log_dump \
     03app_nrf5340_net \
     #
+  # Bootloader not supported on nrf5340 network core
+  BOOTLOADER :=
 else
   PROJECTS ?= $(shell find projects/ -maxdepth 1 -mindepth 1 -type d | tr -d "/" | sed -e s/projects// | sort)
 endif
 
-TESTBED_APPS ?= $(shell find testbed/ -maxdepth 1 -mindepth 1 -type d | tr -d "/" | sed -e s/testbed// | sort)
+OTAP_APPS ?= $(shell find otap/ -maxdepth 1 -mindepth 1 -type d | tr -d "/" | sed -e s/otap// | sort)
+OTAP_APPS := $(filter-out bootloader,$(OTAP_APPS))
 
 # remove incompatible apps (nrf5340, sailbot gateway) for dotbot (v1, v2) builds
 ifneq (,$(filter dotbot-v1,$(BUILD_TARGET)))
   PROJECTS := $(filter-out 01bsp_qdec 01drv_lis3mdl 01drv_move 03app_dotbot_gateway 03app_dotbot_gateway_lr 03app_sailbot 03app_nrf5340_%,$(PROJECTS))
   ARTIFACT_PROJECTS := 03app_dotbot
-  TESTBED_APPS := $(filter-out bootloader partition0 partition1,$(TESTBED_APPS))
 endif
 
 ifneq (,$(filter dotbot-v2,$(BUILD_TARGET)))
   PROJECTS := $(filter-out 03app_dotbot_gateway 03app_dotbot_gateway_lr 03app_sailbot 03app_nrf5340_net,$(PROJECTS))
   ARTIFACT_PROJECTS := 03app_dotbot
-  TESTBED_APPS := $(filter-out bootloader partition0 partition1,$(TESTBED_APPS))
 endif
 
 # remove incompatible apps (nrf5340, dotbot, gateway) for sailbot-v1 build
 ifeq (sailbot-v1,$(BUILD_TARGET))
   PROJECTS := $(filter-out 01bsp_qdec 01drv_lis3mdl 01drv_move 03app_dotbot_gateway 03app_dotbot_gateway_lr 03app_dotbot 03app_nrf5340_%,$(PROJECTS))
   ARTIFACT_PROJECTS := 03app_sailbot
-  TESTBED_APPS := $(filter-out bootloader partition0 partition1,$(TESTBED_APPS))
 endif
 
 # remove incompatible apps (nrf5340) for nrf52833dk/nrf52840dk build
@@ -96,7 +97,7 @@ ifneq (,$(filter nrf5340dk-net,$(BUILD_TARGET)))
   ARTIFACT_PROJECTS := 03app_nrf5340_net
 endif
 
-SRCS ?= $(shell find bsp/ -name "*.[c|h]") $(shell find crypto/ -name "*.[c|h]") $(shell find drv/ -name "*.[c|h]") $(shell find projects/ -name "*.[c|h]") $(shell find testbed/ -name "*.[c|h]")
+SRCS ?= $(shell find bsp/ -name "*.[c|h]") $(shell find crypto/ -name "*.[c|h]") $(shell find drv/ -name "*.[c|h]") $(shell find projects/ -name "*.[c|h]") $(shell find otap/ -name "*.[c|h]")
 CLANG_FORMAT ?= clang-format
 CLANG_FORMAT_TYPE ?= file
 
@@ -107,16 +108,21 @@ ARTIFACTS = $(ARTIFACT_ELF) $(ARTIFACT_HEX)
 
 .PHONY: $(PROJECTS) $(ARTIFACT_PROJECTS) artifacts docker docker-release format check-format
 
-all: $(PROJECTS) $(TESTBED_APPS)
+all: $(PROJECTS) $(OTAP_APPS) $(BOOTLOADER)
 
 $(PROJECTS):
 	@echo "\e[1mBuilding project $@\e[0m"
 	"$(SEGGER_DIR)/bin/emBuild" $(PROJECT_FILE) -project $@ -config $(BUILD_CONFIG) $(PACKAGES_DIR_OPT) -rebuild -verbose
 	@echo "\e[1mDone\e[0m\n"
 
-$(TESTBED_APPS):
-	@echo "\e[1mBuilding testbed application $@\e[0m"
-	"$(SEGGER_DIR)/bin/emBuild" $(PROJECT_FILE) -project $@ -config Release $(PACKAGES_DIR_OPT) -rebuild -verbose
+$(OTAP_APPS):
+	@echo "\e[1mBuilding otap application $@\e[0m"
+	"$(SEGGER_DIR)/bin/emBuild" $(PROJECT_FILE) -project $@ -config $(BUILD_CONFIG) $(PACKAGES_DIR_OPT) -rebuild -verbose
+	@echo "\e[1mDone\e[0m\n"
+
+$(BOOTLOADER):
+	@echo "\e[1mBuilding bootloader application $@\e[0m"
+	"$(SEGGER_DIR)/bin/emBuild" otap/$(BUILD_TARGET)-bootloader.emProject -project $@ -config Release $(PACKAGES_DIR_OPT) -rebuild -verbose
 	@echo "\e[1mDone\e[0m\n"
 
 list-projects:

bsp/nrf/nvmc.c

@@ -53,7 +53,7 @@ void db_nvmc_write(const uint32_t *addr, const void *data, size_t len) {
     // Length must be a multiple of 4 bytes
     assert(len % 4 == 0);
     // writes must be 4 bytes aligned
-    assert(!((uint32_t)addr % 4) && !((uint32_t)data % 4));
+    assert(((uint32_t)addr % 4) && ((uint32_t)data % 4));
 
     uint32_t       *dest_addr = (uint32_t *)addr;
     const uint32_t *data_addr = data;

dist/scripts/otap/.gitignore

@@ -0,0 +1,2 @@
+private_key
+public_key.h

dist/scripts/testbed/dotbot-flash.py → dist/scripts/otap/dotbot-flash.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 
+import os
 import logging
 import time
 
@@ -8,10 +9,13 @@
 from enum import Enum
 
 import click
-from tqdm import tqdm
-
 import serial
 import structlog
+
+from tqdm import tqdm
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+
 from dotbot.hdlc import hdlc_encode, HDLCHandler, HDLCState
 from dotbot.protocol import PROTOCOL_VERSION
 from dotbot.serial_interface import SerialInterface, SerialInterfaceException
@@ -25,14 +29,16 @@
     "nrf52840": 4096,
     "nrf5340-app": 4096,
 }
-
+PRIVATE_KEY_PATH = os.path.join(os.path.dirname(os.path.realpath(__file__)), "private_key")
 
 class MessageType(Enum):
     """Types of bootloader message."""
 
-    OTA_MESSAGE_TYPE_FW = 0
-    OTA_MESSAGE_TYPE_FW_ACK = 1
-    OTA_MESSAGE_TYPE_INFO = 2
+    OTA_MESSAGE_TYPE_START = 0
+    OTA_MESSAGE_TYPE_START_ACK = 1
+    OTA_MESSAGE_TYPE_FW = 2
+    OTA_MESSAGE_TYPE_FW_ACK = 3
+    OTA_MESSAGE_TYPE_INFO = 4
 
 
 class CpuType(Enum):
@@ -109,6 +115,7 @@ def __init__(self, port, baudrate, image):
         self.hdlc_handler = HDLCHandler()
         self.device_info = None
         self.device_info_received = False
+        self.start_ack_received = False
         pad_length = CHUNK_SIZE - (len(image) % CHUNK_SIZE)
         self.image = image + bytearray(b"\xff") * (pad_length + 1)
         self.last_acked_chunk = -1
@@ -121,21 +128,60 @@ def on_byte_received(self, byte):
             payload = self.hdlc_handler.payload
             if not payload:
                 return
-            if payload[0] == MessageType.OTA_MESSAGE_TYPE_FW_ACK.value:
+            if payload[0] == MessageType.OTA_MESSAGE_TYPE_START_ACK.value:
+                self.start_ack_received = True
+            elif payload[0] == MessageType.OTA_MESSAGE_TYPE_FW_ACK.value:
                 self.last_acked_chunk = int.from_bytes(payload[1:5], byteorder="little")
             elif payload[0] == MessageType.OTA_MESSAGE_TYPE_INFO.value:
                 self.device_info = DeviceInfo.from_bytes(payload[1:])
                 self.device_info_received = True
 
     def fetch_device_info(self):
-        while self.device_info_received is False:
+        # while self.device_info_received is False:
+        buffer = bytearray()
+        buffer += int(MessageType.OTA_MESSAGE_TYPE_INFO.value).to_bytes(
+            length=1, byteorder="little"
+        )
+        print("Fetching device info...")
+        self.serial.write(hdlc_encode(buffer))
+        timeout = 0  # ms
+        while self.device_info_received is False and timeout < 100:
+            timeout += 1
+            time.sleep(0.01)
+
+    def send_start_update(self, secure):
+        if secure is True:
+            digest = hashes.Hash(hashes.SHA256())
+            pos = 0
+            while pos + CHUNK_SIZE <= len(self.image) + 1:
+                digest.update(self.image[pos : pos + CHUNK_SIZE])
+                pos += CHUNK_SIZE
+            fw_hash = digest.finalize()
+            private_key_bytes = open(PRIVATE_KEY_PATH, "rb").read()
+            private_key = Ed25519PrivateKey.from_private_bytes(private_key_bytes)
+        attempts = 0
+        while attempts < 3:
             buffer = bytearray()
-            buffer += int(MessageType.OTA_MESSAGE_TYPE_INFO.value).to_bytes(
+            buffer += int(MessageType.OTA_MESSAGE_TYPE_START.value).to_bytes(
                 length=1, byteorder="little"
             )
+            buffer += int((len(self.image) - 1) / CHUNK_SIZE).to_bytes(
+                length=4, byteorder="little"
+            )
+            if secure is True:
+                buffer += fw_hash
+                signature = private_key.sign(bytes(buffer[1:]))
+                buffer += signature
+            print("Sending start update notification...")
             self.serial.write(hdlc_encode(buffer))
-            time.sleep(0.2)
-            print("Fetching device info...")
+            attempts += 1
+            timeout = 0  # ms
+            while self.start_ack_received is False and timeout < 1000:
+                timeout += 1
+                time.sleep(0.01)
+            if self.start_ack_received is True:
+                break
+        return attempts < 3
 
     def flash(self):
         page_size = PAGE_SIZE_MAP[self.device_info.cpu]
@@ -172,14 +218,20 @@ def flash(self):
     default="/dev/ttyACM0",
     help="Serial port to use to send the firmware.",
 )
+@click.option(
+    "-s",
+    "--secure",
+    is_flag=True,
+    help="Use cryptographic security (hash and signature).",
+)
 @click.option(
     "-y",
     "--yes",
     is_flag=True,
     help="Continue flashing without prompt.",
 )
 @click.argument("image", type=click.File(mode="rb", lazy=True))
-def main(port, yes, image):
+def main(port, secure, yes, image):
     # Disable logging configure in PyDotBot
     structlog.configure(
         wrapper_class=structlog.make_filtering_bound_logger(logging.CRITICAL),
@@ -216,6 +268,10 @@ def main(port, yes, image):
         return
     if yes is False:
         click.confirm("Do you want to continue?", default=True, abort=True)
+    ret = flasher.send_start_update(secure)
+    if ret is False:
+        print("Error: No start acknowledment received. Aborting.")
+        return
     flasher.flash()
     print("Done")
 

dist/scripts/otap/generate_keys.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python
+
+import os
+
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+from cryptography.hazmat.primitives.serialization import (
+    Encoding,
+    PrivateFormat,
+    PublicFormat,
+    NoEncryption,
+)
+
+PRIVATE_KEY_PATH = os.path.join(os.path.dirname(os.path.realpath(__file__)), "private_key")
+PUBLIC_KEY_PATH = os.path.join(os.path.dirname(os.path.realpath(__file__)), "../../../drv/ota/public_key.h")
+
+HEADER_FORMAT = """/*
+ * PLEASE DON'T EDIT
+ *
+ * This file was automatically generated
+ */
+
+#ifndef __{name_upper}_H
+#define __{name_upper}_H
+
+#include <stdint.h>
+
+const uint8_t {name}[] = {{
+    {data}
+}};
+
+#endif /* __{name_upper}_H */
+"""
+
+
+def save_as_c_array(path, name, data):
+    data_str = ", ".join([f"0x{data[i:i+2]}" for i in range(0, len(data), 2)])
+    print(f"Saving '{name}' to {os.path.abspath(path)}")
+    with open(path, "w") as f:
+        f.write(HEADER_FORMAT.format(name=name, name_upper=name.upper(), data=data_str))
+
+
+def main():
+    key_pair = Ed25519PrivateKey.generate()
+    private_key = key_pair.private_bytes(Encoding.Raw, PrivateFormat.Raw, NoEncryption())
+    public_key = key_pair.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw)
+
+    print(f"Generated keys:\n  - private key\t: {private_key.hex()}\n  - public key\t: {public_key.hex()}")
+    print(f"Saving 'private key' to {os.path.abspath(PRIVATE_KEY_PATH)}")
+    with open(PRIVATE_KEY_PATH, "wb") as f:
+        f.write(private_key)
+    save_as_c_array(PUBLIC_KEY_PATH, "public_key", public_key.hex())
+
+if __name__ == "__main__":
+    main()

dist/scripts/testbed/requirements.txt → dist/scripts/otap/requirements.txt

@@ -1,3 +1,4 @@
 click==8.1.7
+cryptography==41.0.5
 tqdm==4.66.1
 pydotbot

doc/doxygen/Doxyfile

@@ -126,8 +126,8 @@ INPUT                  = \
                         ../../bsp \
                         ../../crypto \
                         ../../drv \
+                        ../../otap \
                         ../../projects \
-                        ../../testbed \
                         #
 INPUT_ENCODING         = UTF-8
 FILE_PATTERNS          = \

doc/sphinx/index.md

@@ -4,7 +4,7 @@
 getting_started
 applications
 examples
-testbed
+otap
 api
 ```
 

doc/sphinx/testbed.md → doc/sphinx/otap.md

@@ -1,4 +1,4 @@
-```{include} ../../testbed/README.md
+```{include} ../../otap/README.md
 :relative-images:
 :relative-docs: ../
 ```

dotbot-v1.emProject

@@ -26,7 +26,7 @@
     build_output_file_name="$(OutDir)/$(ProjectName)-$(BuildTarget)$(EXE)"
     build_treat_warnings_as_errors="Yes"
     c_additional_options="-Wno-missing-field-initializers"
-    c_preprocessor_definitions="ARM_MATH_CM4;NRF52833_XXAA;__nRF_FAMILY;CONFIG_NFCT_PINS_AS_GPIOS;FLASH_PLACEMENT=1;BOARD_DOTBOT_V1"
+    c_preprocessor_definitions="ARM_MATH_CM4;NRF52833_XXAA;__nRF_FAMILY;CONFIG_NFCT_PINS_AS_GPIOS;FLASH_PLACEMENT=1;BOARD_DOTBOT_V1;OTA_USE_CRYPTO"
     c_user_include_directories="$(SolutionDir)/../bsp;$(SolutionDir)/../crypto;$(SolutionDir)/../drv;$(PackagesDir)/nRF/Device/Include;$(PackagesDir)/CMSIS_5/CMSIS/Core/Include"
     debug_register_definition_file="$(PackagesDir)/nRF/XML/nrf52833_Registers.xml"
     debug_stack_pointer_start="__stack_end__"
@@ -61,4 +61,5 @@
   <import file_name="projects/projects-crypto.emProject" />
   <import file_name="projects/projects-dotbot.emProject" />
   <import file_name="projects/projects-log-dump.emProject" />
+  <import file_name="otap/otap.emProject" />
 </solution>

dotbot-v2.emProject

@@ -23,7 +23,7 @@
     build_output_file_name="$(OutDir)/$(ProjectName)-$(BuildTarget)$(EXE)"
     build_treat_warnings_as_errors="Yes"
     c_additional_options="-Wno-strict-prototypes"
-    c_preprocessor_definitions="ARM_MATH_ARMV8MML;NRF5340_XXAA;NRF_APPLICATION;__NRF_FAMILY;CONFIG_NFCT_PINS_AS_GPIOS;FLASH_PLACEMENT=1;BOARD_DOTBOT_V2"
+    c_preprocessor_definitions="ARM_MATH_ARMV8MML;NRF5340_XXAA;NRF_APPLICATION;__NRF_FAMILY;CONFIG_NFCT_PINS_AS_GPIOS;FLASH_PLACEMENT=1;BOARD_DOTBOT_V2;OTA_USE_CRYPTO"
     c_user_include_directories="$(SolutionDir)/../bsp;$(SolutionDir)/../crypto;$(SolutionDir)/../drv;$(PackagesDir)/nRF/Device/Include;$(PackagesDir)/CMSIS_5/CMSIS/Core/Include"
     debug_register_definition_file="$(PackagesDir)/nRF/XML/nrf5340_application_Registers.xml"
     debug_stack_pointer_start="__stack_end__"
@@ -62,4 +62,5 @@
   <import file_name="projects/projects-dotbot.emProject" />
   <import file_name="projects/projects-log-dump.emProject" />
   <import file_name="projects/projects-nrf5340-app.emProject" />
+  <import file_name="otap/otap.emProject" />
 </solution>

drv/drv.emProject

@@ -88,7 +88,7 @@
   <project Name="00drv_ota">
     <configuration
       Name="Common"
-      project_dependencies="00bsp_partition(bsp);00bsp_nvmc(bsp)"
+      project_dependencies="00bsp_partition(bsp);00bsp_nvmc(bsp);00crypto_ed25519(crypto);00crypto_sha256(crypto)"
       project_directory="ota"
       project_type="Library" />
     <file file_name="ota.c" />