gm/body/crypto/sign.py

39 lines
1.0 KiB
Python
Executable File

#!/usr/bin/env python3
import os
import sys
import struct
import hashlib
from Crypto.PublicKey import RSA
import binascii
# increment this to make new hardware not run old versions
VERSION = 2
if __name__ == "__main__":
with open(sys.argv[3], encoding='utf8') as k:
rsa = RSA.importKey(k.read())
with open(sys.argv[1], "rb") as f:
dat = f.read()
print("signing", len(dat), "bytes")
with open(sys.argv[2], "wb") as f:
if os.getenv("SETLEN") is not None:
# add the version at the end
dat += b"VERS" + struct.pack("I", VERSION)
# add the length at the beginning
x = struct.pack("I", len(dat)) + dat[4:]
# mock signature of dat[4:]
dd = hashlib.sha1(dat[4:]).digest()
else:
x = dat
dd = hashlib.sha1(dat).digest()
print("hash:", str(binascii.hexlify(dd), "utf-8"))
dd = b"\x00\x01" + b"\xff" * 0x69 + b"\x00" + dd
rsa_out = pow(int.from_bytes(dd, byteorder='big', signed=False), rsa.d, rsa.n)
sig = (hex(rsa_out)[2:].rjust(0x100, '0'))
x += binascii.unhexlify(sig)
f.write(x)