RRG-Proxmark3/tools/xorcheck.py
2020-02-21 16:29:52 +01:00

50 lines
1.5 KiB
Python
Executable File

#!/usr/bin/env python3
# xorcheck.py - find xor values for 8-bit LRC
#
# Adam Laurie <adam@algroup.co.uk>
# http://rfidiot.org/
#
# This code is copyright (c) Adam Laurie, 2009, All rights reserved.
# For non-commercial use only, the following terms apply - for all other
# uses, please contact the author:
#
# This code is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This code is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
import sys
import os
if(len(sys.argv) < 3):
print("""
\t{0} - Generate final byte for XOR LRC
Usage: {0} <ID Byte1> <ID Byte2> ... <LRC>
\tSpecifying the bytes of a UID with a known LRC will find the last byte value
\tneeded to generate that LRC with a rolling XOR. All bytes should be specified in HEX.
Example:
\t{0} 04 00 80 64 ba
Should produce the output:
\tTarget (BA) requires final LRC XOR byte value: 5A\n""".format(sys.argv[0]))
os._exit(True)
target= int(sys.argv[len(sys.argv) - 1],16)
lrc= 0x00
for i in range(len(sys.argv) - 1):
lrc ^= int(sys.argv[i + 1],16)
print('\nTarget (%02X) requires final LRC XOR byte value: %02X\n' % (target,lrc))