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mirror of https://github.com/trezor/trezor-firmware.git synced 2024-12-22 14:28:07 +00:00
trezor-firmware/bootloader/firmware_sign.py
2018-10-30 18:13:11 +01:00

233 lines
6.7 KiB
Python
Executable File

#!/usr/bin/env python3
from __future__ import print_function
import argparse
import hashlib
import struct
import ecdsa
try:
raw_input
except:
raw_input = input
SLOTS = 3
pubkeys = {
1: "04d571b7f148c5e4232c3814f777d8faeaf1a84216c78d569b71041ffc768a5b2d810fc3bb134dd026b57e65005275aedef43e155f48fc11a32ec790a93312bd58",
2: "0463279c0c0866e50c05c799d32bd6bab0188b6de06536d1109d2ed9ce76cb335c490e55aee10cc901215132e853097d5432eda06b792073bd7740c94ce4516cb1",
3: "0443aedbb6f7e71c563f8ed2ef64ec9981482519e7ef4f4aa98b27854e8c49126d4956d300ab45fdc34cd26bc8710de0a31dbdf6de7435fd0b492be70ac75fde58",
4: "04877c39fd7c62237e038235e9c075dab261630f78eeb8edb92487159fffedfdf6046c6f8b881fa407c4a4ce6c28de0b19c1f4e29f1fcbc5a58ffd1432a3e0938a",
5: "047384c51ae81add0a523adbb186c91b906ffb64c2c765802bf26dbd13bdf12c319e80c2213a136c8ee03d7874fd22b70d68e7dee469decfbbb510ee9a460cda45",
}
INDEXES_START = len("TRZR") + struct.calcsize("<I")
SIG_START = INDEXES_START + 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")
parser.add_argument(
"-s",
"--sign",
dest="sign",
action="store_true",
help="Add signature to firmware slot",
)
parser.add_argument(
"-p", "--pem", dest="pem", action="store_true", help="Use PEM instead of SECEXP"
)
parser.add_argument(
"-g",
"--generate",
dest="generate",
action="store_true",
help="Generate new ECDSA keypair",
)
return parser.parse_args()
def prepare(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(data):
# Analyses given firmware and prints out
# status of included signatures
try:
indexes = [ord(x) for x in data[INDEXES_START : INDEXES_START + SLOTS]]
except:
indexes = [x for x in data[INDEXES_START : INDEXES_START + SLOTS]]
to_sign = prepare(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:
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:
print("Slot #%d signature: INVALID" % (x + 1), signature.hex())
def modify(data, slot, index, signature):
# Replace signature in data
# Put index to data
data = (
data[: INDEXES_START + slot - 1] + bytes([index]) + data[INDEXES_START + slot :]
)
# Put signature to data
data = (
data[: SIG_START + 64 * (slot - 1)] + signature + data[SIG_START + 64 * slot :]
)
return data
def sign(data, is_pem):
# Ask for index and private key and signs the firmware
slot = int(raw_input("Enter signature slot (1-%d): " % SLOTS))
if slot < 1 or slot > SLOTS:
raise Exception("Invalid slot")
if is_pem:
print("Paste ECDSA private key in PEM format and press Enter:")
print("(blank private key removes the signature on given index)")
pem_key = ""
while True:
key = raw_input()
pem_key += key + "\n"
if key == "":
break
if pem_key.strip() == "":
# Blank key,let's remove existing signature from slot
return modify(data, slot, 0, "\x00" * 64)
key = ecdsa.SigningKey.from_pem(pem_key)
else:
print("Paste SECEXP (in hex) and press Enter:")
print("(blank private key removes the signature on given index)")
secexp = raw_input()
if secexp.strip() == "":
# Blank key,let's remove existing signature from slot
return modify(data, slot, 0, "\x00" * 64)
key = ecdsa.SigningKey.from_secret_exponent(
secexp=int(secexp, 16),
curve=ecdsa.curves.SECP256k1,
hashfunc=hashlib.sha256,
)
to_sign = prepare(data)[256:] # without meta
# Locate proper index of current signing key
pubkey = "04" + key.get_verifying_key().to_string().hex()
index = None
for i, pk in pubkeys.items():
if pk == pubkey:
index = i
break
if index == 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 main(args):
if args.generate:
key = ecdsa.SigningKey.generate(
curve=ecdsa.curves.SECP256k1, hashfunc=hashlib.sha256
)
print("PRIVATE KEY (SECEXP):")
print(key.to_string().hex())
print()
print("PRIVATE KEY (PEM):")
print(key.to_pem())
print("PUBLIC KEY:")
print("04" + key.get_verifying_key().to_string().hex())
return
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"TRZR":
print("Metadata has been added...")
data = prepare(data)
if data[:4] != b"TRZR":
raise Exception("Firmware header expected")
print("Firmware size %d bytes" % len(data))
check_signatures(data)
if args.sign:
data = sign(data, args.pem)
check_signatures(data)
fp = open(args.path, "wb")
fp.write(data)
fp.close()
if __name__ == "__main__":
args = parse_args()
main(args)