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mirror of https://github.com/trezor/trezor-firmware.git synced 2024-12-13 01:48:21 +00:00
trezor-firmware/legacy/bootloader/firmware_sign_dev.py
2023-01-02 11:03:38 +01:00

334 lines
9.2 KiB
Python

#!/usr/bin/env python3
import argparse
import hashlib
import struct
import ecdsa
from ecdsa import BadSignatureError
SLOTS = 3
pubkeys_dev = {
1: "042c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991ae31a9c671a36543f46cea8fce6984608aa316aa0472a7eed08847440218cb2f",
2: "04edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f2211452c88a66eb8ac3c19a1cc3a3fc6d72506f6fce2025f738d8b55f29f22125eb0a4",
3: "04665f660a5052be7a95546a02179058d93d3e08a779734914594346075bb0afd45113948d72cf3dc8f2b70ee02dc1695d051bb0c6da2a914a69045e3277682d3b",
}
privkeys_dev = {
1: "0x4444444444444444444444444444444444444444444444444444444444444444",
2: "0x4545454545454545454545454545454545454545454545454545454545454545",
3: "0xbfc4bca9c9c228a16639d3503d999a733a439210b64cebe757a4fd03ca46a5c8",
}
FWHEADER_SIZE = 1024
SIGNATURES_START = 6 * 4 + 8 + 512
INDEXES_START = SIGNATURES_START + 3 * 64
INDEXES_START_OLD = len("TRZR") + struct.calcsize("<I")
SIG_START = INDEXES_START_OLD + SLOTS + 1 + 52
def parse_args():
parser = argparse.ArgumentParser(
description="Commandline tool for signing Trezor firmware."
)
parser.add_argument("-f", "--file", dest="path", help="Firmware file to modify")
return parser.parse_args()
def pad_to_size(data, size):
if len(data) > size:
raise ValueError("Chunk too big already")
if len(data) == size:
return data
return data + b"\xFF" * (size - len(data))
# see memory.h for details
def prepare_hashes(data):
# process chunks
start = 0
end = (64 - 1) * 1024
hashes = []
for i in range(16):
sector = data[start:end]
if len(sector) > 0:
chunk = pad_to_size(sector, end - start)
hashes.append(hashlib.sha256(chunk).digest())
else:
hashes.append(b"\x00" * 32)
start = end
end += 64 * 1024
return hashes
def check_hashes(data):
expected_hashes = data[0x20 : 0x20 + 16 * 32]
hashes = b""
for h in prepare_hashes(data[FWHEADER_SIZE:]):
hashes += h
if expected_hashes == hashes:
print("HASHES OK")
else:
print("HASHES NOT OK")
def update_hashes_in_header(data):
# Store hashes in the firmware header
data = bytearray(data)
o = 0
for h in prepare_hashes(data[FWHEADER_SIZE:]):
data[0x20 + o : 0x20 + o + 32] = h
o += 32
return bytes(data)
def get_header(data, zero_signatures=False):
if not zero_signatures:
return data[:FWHEADER_SIZE]
else:
data = bytearray(data[:FWHEADER_SIZE])
data[SIGNATURES_START : SIGNATURES_START + 3 * 64 + 3] = b"\x00" * (3 * 64 + 3)
return bytes(data)
def check_size(data):
size = struct.unpack("<L", data[12:16])[0]
assert size == len(data) - 1024
def check_signatures(data):
# Analyses given firmware and prints out
# status of included signatures
indexes = [x for x in data[INDEXES_START : INDEXES_START + SLOTS]]
to_sign = get_header(data, zero_signatures=True)
fingerprint = hashlib.sha256(to_sign).hexdigest()
print("Firmware fingerprint:", fingerprint)
used = []
for x in range(SLOTS):
signature = data[SIGNATURES_START + 64 * x : SIGNATURES_START + 64 * x + 64]
if indexes[x] == 0:
print(f"Slot #{x + 1}", "is empty")
else:
pubkeys = pubkeys_dev
pk = pubkeys[indexes[x]]
verify = ecdsa.VerifyingKey.from_string(
bytes.fromhex(pk)[1:],
curve=ecdsa.curves.SECP256k1,
hashfunc=hashlib.sha256,
)
try:
verify.verify(signature, to_sign, hashfunc=hashlib.sha256)
if indexes[x] in used:
print(f"Slot #{x + 1} signature: DUPLICATE", signature.hex())
else:
used.append(indexes[x])
print(f"Slot #{x + 1} signature: VALID", signature.hex())
except Exception:
print(f"Slot #{x + 1} signature: INVALID", signature.hex())
def modify(data, slot, index, signature):
data = bytearray(data)
# put index to data
data[INDEXES_START + slot - 1] = index
# put signature to data
data[SIGNATURES_START + 64 * (slot - 1) : SIGNATURES_START + 64 * slot] = signature
return bytes(data)
def sign(data, slot, secexp):
key = ecdsa.SigningKey.from_secret_exponent(
secexp=int(secexp, 16),
curve=ecdsa.curves.SECP256k1,
hashfunc=hashlib.sha256,
)
to_sign = get_header(data, zero_signatures=True)
# Locate proper index of current signing key
pubkey = "04" + key.get_verifying_key().to_string().hex()
index = None
pubkeys = pubkeys_dev
for i, pk in pubkeys.items():
if pk == pubkey:
index = i
break
if index is None:
raise Exception("Unable to find private key index. Unknown private key?")
signature = key.sign_deterministic(to_sign, hashfunc=hashlib.sha256)
return modify(data, slot, index, signature)
def prepare_old(data):
# Takes raw OR signed firmware and clean out metadata structure
# This produces 'clean' data for signing
meta = b"TRZR" # magic
if data[:4] == b"TRZR":
meta += data[4 : 4 + struct.calcsize("<I")]
else:
meta += struct.pack("<I", len(data)) # length of the code
meta += b"\x00" * SLOTS # signature index #1-#3
meta += b"\x01" # flags
meta += b"\x00" * 52 # reserved
meta += b"\x00" * 64 * SLOTS # signature #1-#3
if data[:4] == b"TRZR":
# Replace existing header
out = meta + data[len(meta) :]
else:
# create data from meta + code
out = meta + data
return out
def check_signatures_old(data):
# Analyses given firmware and prints out
# status of included signatures
try:
indexes = [ord(x) for x in data[INDEXES_START_OLD : INDEXES_START_OLD + SLOTS]]
except TypeError:
indexes = [x for x in data[INDEXES_START_OLD : INDEXES_START_OLD + SLOTS]]
to_sign = prepare_old(data)[256:] # without meta
fingerprint = hashlib.sha256(to_sign).hexdigest()
print("Firmware fingerprint:", fingerprint)
used = []
for x in range(SLOTS):
signature = data[SIG_START + 64 * x : SIG_START + 64 * x + 64]
if indexes[x] == 0:
print("Slot #%d" % (x + 1), "is empty")
else:
pubkeys = pubkeys_dev
pk = pubkeys[indexes[x]]
verify = ecdsa.VerifyingKey.from_string(
bytes.fromhex(pk)[1:],
curve=ecdsa.curves.SECP256k1,
hashfunc=hashlib.sha256,
)
try:
verify.verify(signature, to_sign, hashfunc=hashlib.sha256)
if indexes[x] in used:
print("Slot #%d signature: DUPLICATE" % (x + 1), signature.hex())
else:
used.append(indexes[x])
print("Slot #%d signature: VALID" % (x + 1), signature.hex())
except BadSignatureError:
print("Slot #%d signature: INVALID" % (x + 1), signature.hex())
def modify_old(data, slot, index, signature):
# Replace signature in data
# Put index to data
data = (
data[: INDEXES_START_OLD + slot - 1]
+ bytes([index])
+ data[INDEXES_START_OLD + slot :]
)
# Put signature to data
data = (
data[: SIG_START + 64 * (slot - 1)] + signature + data[SIG_START + 64 * slot :]
)
return data
def sign_old(data, slot, secexp):
key = ecdsa.SigningKey.from_secret_exponent(
secexp=int(secexp, 16),
curve=ecdsa.curves.SECP256k1,
hashfunc=hashlib.sha256,
)
to_sign = prepare_old(data)[256:] # without meta
# Locate proper index of current signing key
pubkey = "04" + key.get_verifying_key().to_string().hex()
index = None
pubkeys = pubkeys_dev
for i, pk in pubkeys.items():
if pk == pubkey:
index = i
break
if index is None:
raise Exception("Unable to find private key index. Unknown private key?")
signature = key.sign_deterministic(to_sign, hashfunc=hashlib.sha256)
return modify_old(data, slot, index, signature)
def main(args):
if not args.path:
raise Exception("-f/--file is required")
data = open(args.path, "rb").read()
assert len(data) % 4 == 0
if data[:4] != b"TRZF":
raise Exception("Firmware header expected")
data = update_hashes_in_header(data)
print(f"Firmware size {len(data)} bytes")
check_size(data)
check_signatures(data)
check_hashes(data)
data = sign(data, 1, privkeys_dev[1])
data = sign(data, 2, privkeys_dev[2])
data = sign(data, 3, privkeys_dev[3])
check_signatures(data)
check_hashes(data)
fp = open(args.path, "wb")
fp.write(data)
fp.close()
data = prepare_old(data)
check_signatures_old(data)
data = sign_old(data, 1, privkeys_dev[1])
data = sign_old(data, 2, privkeys_dev[2])
data = sign_old(data, 3, privkeys_dev[3])
check_signatures_old(data)
fp = open(args.path, "wb")
fp.write(data)
fp.close()
if __name__ == "__main__":
args = parse_args()
main(args)