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- Support toboot API 2.0 - Allow injecting private key into firmware
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,18 +1,24 @@ | ||
| language: c | ||
| sudo: required | ||
| dist: trusty | ||
|
|
||
| addons: | ||
| apt: | ||
| packages: | ||
| - gcc-arm-none-eabi | ||
| - libnewlib-arm-none-eabi | ||
| - python-pip | ||
| - openssl | ||
|
|
||
| install: | ||
| - pip install asn1crypto --user | ||
| - sudo apt-add-repository -y ppa:team-gcc-arm-embedded/ppa | ||
| - sudo apt-get update | ||
| - sudo apt-get install -yy gcc-arm-embedded | ||
|
|
||
| script: | ||
| - 'cd u2f && make && cd ..' | ||
| - 'cd u2f && make clean certclean && cd ..' | ||
| - 'cd u2f && make ENFORCE_DEBUG_LOCK=1 && cd ..' | ||
| - 'cd u2f' | ||
| - 'make' | ||
| - 'make clean certclean' | ||
| - 'make ENFORCE_DEBUG_LOCK=1' | ||
| - 'openssl ecparam -name prime256v1 -genkey -noout -outform der -out key.der' | ||
| - './inject_key.py --key key.der --ctr 1001' | ||
| - 'cd ..' |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,68 @@ | ||
| #!/usr/bin/env python | ||
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| # | ||
| # Use this script to inject your own private key and authentication counter | ||
| # into U2F binary. Might be useful if you want keys to survive firmware updates. | ||
| # | ||
| # Example: | ||
| # | ||
| # Generate EC private key with openssl: | ||
| # > openssl ecparam -name prime256v1 -genkey -noout -outform der > key.der | ||
| # | ||
| # Inject generated key into u2f.bin and set auth counter to 100: | ||
| # > python3 inject_key.py --key key.der --ctr 100 | ||
| # | ||
|
|
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| from __future__ import print_function | ||
| from asn1crypto.keys import ECPrivateKey | ||
| import hashlib | ||
| import argparse | ||
| import sys | ||
| import struct | ||
| import os | ||
| import tempfile | ||
| import subprocess | ||
|
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| parser = argparse.ArgumentParser() | ||
| parser.add_argument("--elf", default="build/u2f.elf", | ||
| help=".elf file to inject keys into") | ||
| parser.add_argument("--key", help="EC private key in DER format") | ||
| parser.add_argument("--ctr", default=1, type=int, help="value of auth counter") | ||
| args = parser.parse_args() | ||
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| # load and parse private key | ||
| if args.key: | ||
| with open(args.key, "rb") as f: | ||
| der = f.read() | ||
| else: | ||
| stdin = sys.stdin.buffer if hasattr(sys.stdin, "buffer") else sys.stdin | ||
| der = stdin.read() | ||
| key = ECPrivateKey.load(der) | ||
|
|
||
| # convert key into raw bytes and calculate it's sha256 | ||
| key_bytes = bytearray.fromhex(format(key["private_key"].native, '064x')) | ||
| key_hash = hashlib.sha256(key_bytes).digest() | ||
|
|
||
| # fill authentication counter | ||
| ctr_bytes = struct.pack("<I", args.ctr) * 256 | ||
|
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||
| # pad key and append ctr to produce 2k output blob | ||
| blob = (key_bytes + key_hash).ljust(1024, b"\x00") + ctr_bytes | ||
|
|
||
| assert len(blob) == 2048 | ||
| fname, fext = os.path.splitext(args.elf) | ||
| assert fext == ".elf" | ||
|
|
||
| with tempfile.NamedTemporaryFile(delete=True) as f: | ||
| f.write(blob) | ||
| f.flush() | ||
| # replace contents of .flash_storage section with desired key and counter | ||
| ret = subprocess.call(["arm-none-eabi-objcopy", "--update-section", | ||
| ".flash_storage=" + f.name, args.elf]) | ||
| if ret != 0: | ||
| raise Exception("Failed to patch .elf file!") | ||
| # generate binary for bootloader | ||
| ret = subprocess.call(["arm-none-eabi-objcopy", "-O", "binary", | ||
| args.elf, fname + ".bin"]) | ||
| if ret != 0: | ||
| raise Exception("Failed to create .bin file!") |
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