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

   1 //-----------------------------------------------------------------------------
   2 //
   3 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   4 // at your option, any later version. See the LICENSE.txt file for the text of
   5 // the license.
   6 //-----------------------------------------------------------------------------
   7 // Low frequency G Prox II tag commands
   8 // Biphase, rf/ , 96 bits  (unknown key calc + some bits)
   9 //-----------------------------------------------------------------------------
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <inttypes.h>
  13 #include "cmdlfgproxii.h"
  14 #include "proxmark3.h"
  15 #include "ui.h"
  16 #include "util.h"
  17 #include "graph.h"
  18 #include "cmdparser.h"
  19 #include "cmddata.h"
  20 #include "cmdmain.h"
  21 #include "cmdlf.h"
  22 #include "lfdemod.h"
  23 static int CmdHelp(const char *Cmd);
  24
  25 //by marshmellow
  26 //attempts to demodulate and identify a G_Prox_II verex/chubb card
  27 //WARNING: if it fails during some points it will destroy the DemodBuffer data
  28 // but will leave the GraphBuffer intact.
  29 //if successful it will push askraw data back to demod buffer ready for emulation
  30 int CmdG_Prox_II_Demod(const char *Cmd)
  31 {
  32         if (!ASKbiphaseDemod(Cmd, false)){
  33                 if (g_debugMode) PrintAndLog("Error gProxII: ASKbiphaseDemod failed 1st try");
  34                 return 0;
  35         }
  36         size_t size = DemodBufferLen;
  37         //call lfdemod.c demod for gProxII
  38         int ans = gProxII_Demod(DemodBuffer, &size);
  39         if (ans < 0){
  40                 if (g_debugMode) PrintAndLog("Error gProxII_Demod");
  41                 return 0;
  42         }
  43         //got a good demod of 96 bits
  44         uint8_t ByteStream[8] = {0x00};
  45         uint8_t xorKey=0;
  46         size_t startIdx = ans + 6; //start after 6 bit preamble
  47
  48         uint8_t bits_no_spacer[90];
  49         //so as to not mess with raw DemodBuffer copy to a new sample array
  50         memcpy(bits_no_spacer, DemodBuffer + startIdx, 90);
  51         // remove the 18 (90/5=18) parity bits (down to 72 bits (96-6-18=72))
  52         size_t bitLen = removeParity(bits_no_spacer, 0, 5, 3, 90); //source, startloc, paritylen, ptype, length_to_run
  53         if (bitLen != 72) {
  54                 if (g_debugMode) PrintAndLog("Error gProxII: spacer removal did not produce 72 bits: %u, start: %u", bitLen, startIdx);
  55                 return 0;
  56         }
  57         // get key and then get all 8 bytes of payload decoded
  58         xorKey = (uint8_t)bytebits_to_byteLSBF(bits_no_spacer, 8);
  59         for (size_t idx = 0; idx < 8; idx++) {
  60                 ByteStream[idx] = ((uint8_t)bytebits_to_byteLSBF(bits_no_spacer+8 + (idx*8),8)) ^ xorKey;
  61                 if (g_debugMode) PrintAndLog("byte %u after xor: %02x", (unsigned int)idx, ByteStream[idx]);
  62         }
  63         //now ByteStream contains 8 Bytes (64 bits) of decrypted raw tag data
  64         //
  65         uint8_t fmtLen = ByteStream[0]>>2;
  66         uint32_t FC = 0;
  67         uint32_t Card = 0;
  68         //get raw 96 bits to print
  69         uint32_t raw1 = bytebits_to_byte(DemodBuffer+ans,32);
  70         uint32_t raw2 = bytebits_to_byte(DemodBuffer+ans+32, 32);
  71         uint32_t raw3 = bytebits_to_byte(DemodBuffer+ans+64, 32);
  72
  73         if (fmtLen==36){
  74                 FC = ((ByteStream[3] & 0x7F)<<7) | (ByteStream[4]>>1);
  75                 Card = ((ByteStream[4]&1)<<19) | (ByteStream[5]<<11) | (ByteStream[6]<<3) | (ByteStream[7]>>5);
  76                 PrintAndLog("G-Prox-II Found: FmtLen %d, FC %u, Card %u", (int)fmtLen, FC, Card);
  77         } else if(fmtLen==26){
  78                 FC = ((ByteStream[3] & 0x7F)<<1) | (ByteStream[4]>>7);
  79                 Card = ((ByteStream[4]&0x7F)<<9) | (ByteStream[5]<<1) | (ByteStream[6]>>7);
  80                 PrintAndLog("G-Prox-II Found: FmtLen %d, FC %u, Card %u", (int)fmtLen, FC, Card);
  81         } else {
  82                 PrintAndLog("Unknown G-Prox-II Fmt Found: FmtLen %d",(int)fmtLen);
  83                 PrintAndLog("Decoded Raw: %s", sprint_hex(ByteStream, 8));
  84         }
  85         PrintAndLog("Raw: %08x%08x%08x", raw1,raw2,raw3);
  86         setDemodBuf(DemodBuffer+ans, 96, 0);
  87         return 1;
  88 }
  89 //by marshmellow
  90 //see ASKDemod for what args are accepted
  91 int CmdG_Prox_II_Read(const char *Cmd) {
  92         // read lf silently
  93         lf_read(true, 10000);
  94         // demod and output viking ID
  95         return CmdG_Prox_II_Demod(Cmd);
  96 }
  97
  98 static command_t CommandTable[] = {
  99         {"help",  CmdHelp,            1, "This help"},
 100         {"demod", CmdG_Prox_II_Demod, 1, "Demodulate a G Prox II tag from the GraphBuffer"},
 101         {"read",  CmdG_Prox_II_Read,  0, "Attempt to read and Extract tag data from the antenna"},
 102         {NULL, NULL, 0, NULL}
 103 };
 104
 105 int CmdLF_G_Prox_II(const char *Cmd) {
 106         CmdsParse(CommandTable, Cmd);
 107         return 0;
 108 }
 109
 110 int CmdHelp(const char *Cmd) {
 111         CmdsHelp(CommandTable);
 112         return 0;
 113 }