# # Option ROM signing utility # # Authors: # Jan Kiszka <jan.kiszka@siemens.com> # # This work is licensed under the terms of the GNU GPL, version 2 or later. # See the COPYING file in the top-level directory. import sys import struct if len(sys.argv) < 3: print('usage: signrom.py input output') sys.exit(1) fin = open(sys.argv[1], 'rb') fout = open(sys.argv[2], 'wb') fin.seek(2) size = ord(fin.read(1)) * 512 - 1 fin.seek(0) data = fin.read(size) fout.write(data) checksum = 0 for b in data: # catch Python 2 vs. 3 differences if isinstance(b, int): checksum += b else: checksum += ord(b) checksum = (256 - checksum) % 256 # Python 3 no longer allows chr(checksum) fout.write(struct.pack('B', checksum)) fin.close() fout.close()