tools/xorcheck.py

   1 #!/usr/bin/env python3
   2
   3 #  xorcheck.py - find xor values for 8-bit LRC
   4 #
   5 #  Adam Laurie <adam@algroup.co.uk>
   6 #  http://rfidiot.org/
   7 #
   8 #  This code is copyright (c) Adam Laurie, 2009, All rights reserved.
   9 #  For non-commercial use only, the following terms apply - for all other
  10 #  uses, please contact the author:
  11 #
  12 #    This code is free software; you can redistribute it and/or modify
  13 #    it under the terms of the GNU General Public License as published by
  14 #    the Free Software Foundation; either version 2 of the License, or
  15 #    (at your option) any later version.
  16 #
  17 #    This code is distributed in the hope that it will be useful,
  18 #    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 #    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 #    GNU General Public License for more details.
  21 #
  22
  23 import sys
  24 import os
  25
  26 if(len(sys.argv) < 3):
  27     print("""
  28 \t{0} - Generate final byte for XOR LRC
  29
  30 Usage: {0} <ID Byte1> <ID Byte2> ... <LRC>
  31
  32 \tSpecifying the bytes of a UID with a known LRC will find the last byte value
  33 \tneeded to generate that LRC with a rolling XOR. All bytes should be specified in HEX.
  34
  35 Example:
  36
  37 \t{0} 04 00 80 64 ba
  38
  39 Should produce the output:
  40
  41 \tTarget (BA) requires final LRC XOR byte value: 5A\n""".format(sys.argv[0]))
  42     os._exit(True)
  43
  44 target= int(sys.argv[len(sys.argv) - 1],16)
  45
  46 lrc= 0x00
  47 for i in range(len(sys.argv) - 1):
  48     lrc ^= int(sys.argv[i + 1],16)
  49 print('\nTarget (%02X) requires final LRC XOR byte value: %02X\n' % (target,lrc))