git.zerfleddert.de Git - proxmark3-svn/blob - client/cmdanalyse.c

   1 //-----------------------------------------------------------------------------
   2 // Copyright (C) 2016 iceman
   3 //
   4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   5 // at your option, any later version. See the LICENSE.txt file for the text of
   6 // the license.
   7 //-----------------------------------------------------------------------------
   8 // Analyse bytes commands
   9 //-----------------------------------------------------------------------------
  10 #include "cmdanalyse.h"
  11
  12 static int CmdHelp(const char *Cmd);
  13
  14 int usage_analyse_lcr(void) {
  15         PrintAndLog("Specifying the bytes of a UID with a known LRC will find the last byte value");
  16         PrintAndLog("needed to generate that LRC with a rolling XOR. All bytes should be specified in HEX.");
  17         PrintAndLog("");
  18         PrintAndLog("Usage:  analyse lcr [h] <bytes>");
  19         PrintAndLog("Options:");
  20         PrintAndLog("           h          This help");
  21         PrintAndLog("           <bytes>    bytes to calc missing XOR in a LCR");
  22         PrintAndLog("");
  23         PrintAndLog("Samples:");
  24         PrintAndLog("           analyse lcr 04008064BA");
  25         PrintAndLog("expected output: Target (BA) requires final LRC XOR byte value: 5A");
  26         return 0;
  27 }
  28 static uint8_t calculateLRC( uint8_t* bytes, uint8_t len) {
  29     uint8_t LRC = 0;
  30     for (uint8_t i = 0; i < len; i++)
  31         LRC ^= bytes[i];
  32     return LRC;
  33 }
  34
  35 int CmdAnalyseLCR(const char *Cmd) {
  36         uint8_t data[50];
  37         char cmdp = param_getchar(Cmd, 0);
  38         if (strlen(Cmd) == 0|| cmdp == 'h' || cmdp == 'H') return usage_analyse_lcr();
  39
  40         int len = 0;
  41         param_gethex_ex(Cmd, 0, data, &len);
  42         if ( len%2 ) return usage_analyse_lcr();
  43         len >>= 1;
  44         uint8_t finalXor = calculateLRC(data, len);
  45         PrintAndLog("Target [%02X] requires final LRC XOR byte value: 0x%02X",data[len-1] ,finalXor);
  46         return 0;
  47 }
  48
  49 static command_t CommandTable[] = {
  50         {"help",            CmdHelp,            1, "This help"},
  51         {"lcr",                         CmdAnalyseLCR,          0, "Generate final byte for XOR LRC"},
  52         {NULL, NULL, 0, NULL}
  53 };
  54
  55 int CmdAnalyse(const char *Cmd) {
  56         clearCommandBuffer();
  57         CmdsParse(CommandTable, Cmd);
  58         return 0;
  59 }
  60
  61 int CmdHelp(const char *Cmd) {
  62         CmdsHelp(CommandTable);
  63         return 0;
  64 }