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

   1 //-----------------------------------------------------------------------------
   2 // Copyright (C) 2010 iZsh <izsh at fail0verflow.com>
   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 // Low frequency TI commands
   9 //-----------------------------------------------------------------------------
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include "crc16.h"
  14 #include "proxusb.h"
  15 #include "proxmark3.h"
  16 #include "data.h"
  17 #include "ui.h"
  18 #include "graph.h"
  19 #include "cmdparser.h"
  20 #include "cmdlfti.h"
  21
  22 static int CmdHelp(const char *Cmd);
  23
  24 int CmdTIDemod(const char *Cmd)
  25 {
  26   /* MATLAB as follows:
  27     f_s = 2000000;  % sampling frequency
  28     f_l = 123200;   % low FSK tone
  29     f_h = 134200;   % high FSK tone
  30
  31     T_l = 119e-6;   % low bit duration
  32     T_h = 130e-6;   % high bit duration
  33
  34     l = 2*pi*ones(1, floor(f_s*T_l))*(f_l/f_s);
  35     h = 2*pi*ones(1, floor(f_s*T_h))*(f_h/f_s);
  36
  37     l = sign(sin(cumsum(l)));
  38     h = sign(sin(cumsum(h)));
  39   */
  40
  41   // 2M*16/134.2k = 238
  42   static const int LowTone[] = {
  43     1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
  44     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  45     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  46     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  47     1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
  48     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  49     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  50     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  51     1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
  52     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  53     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  54     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  55     1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
  56     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1, -1, -1, -1, -1, -1, -1,
  57     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1
  58   };
  59   // 2M*16/123.2k = 260
  60   static const int HighTone[] = {
  61     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  62     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  63     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  64     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  65     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  66     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1,
  67     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  68     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  69     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  70     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  71     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1,
  72     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  73     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  74     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  75     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  76     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1, -1,
  77     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1,
  78     1, 1, 1, 1, 1, 1, 1, 1
  79   };
  80   int lowLen = sizeof(LowTone)/sizeof(int);
  81   int highLen = sizeof(HighTone)/sizeof(int);
  82   int convLen = (highLen>lowLen)?highLen:lowLen;
  83   uint16_t crc;
  84   int i, j, TagType;
  85   int lowSum = 0, highSum = 0;;
  86   int lowTot = 0, highTot = 0;
  87
  88   for (i = 0; i < GraphTraceLen - convLen; i++) {
  89     lowSum = 0;
  90     highSum = 0;;
  91
  92     for (j = 0; j < lowLen; j++) {
  93       lowSum += LowTone[j]*GraphBuffer[i+j];
  94     }
  95     for (j = 0; j < highLen; j++) {
  96       highSum += HighTone[j]*GraphBuffer[i+j];
  97     }
  98     lowSum = abs((100*lowSum) / lowLen);
  99     highSum = abs((100*highSum) / highLen);
 100     lowSum = (lowSum<0)?-lowSum:lowSum;
 101     highSum = (highSum<0)?-highSum:highSum;
 102
 103     GraphBuffer[i] = (highSum << 16) | lowSum;
 104   }
 105
 106   for (i = 0; i < GraphTraceLen - convLen - 16; i++) {
 107     lowTot = 0;
 108     highTot = 0;
 109     // 16 and 15 are f_s divided by f_l and f_h, rounded
 110     for (j = 0; j < 16; j++) {
 111       lowTot += (GraphBuffer[i+j] & 0xffff);
 112     }
 113     for (j = 0; j < 15; j++) {
 114       highTot += (GraphBuffer[i+j] >> 16);
 115     }
 116     GraphBuffer[i] = lowTot - highTot;
 117   }
 118
 119   GraphTraceLen -= (convLen + 16);
 120
 121   RepaintGraphWindow();
 122
 123   // TI tag data format is 16 prebits, 8 start bits, 64 data bits,
 124   // 16 crc CCITT bits, 8 stop bits, 15 end bits
 125
 126   // the 16 prebits are always low
 127   // the 8 start and stop bits of a tag must match
 128   // the start/stop prebits of a ro tag are 01111110
 129   // the start/stop prebits of a rw tag are 11111110
 130   // the 15 end bits of a ro tag are all low
 131   // the 15 end bits of a rw tag match bits 15-1 of the data bits
 132
 133   // Okay, so now we have unsliced soft decisions;
 134   // find bit-sync, and then get some bits.
 135   // look for 17 low bits followed by 6 highs (common pattern for ro and rw tags)
 136   int max = 0, maxPos = 0;
 137   for (i = 0; i < 6000; i++) {
 138     int j;
 139     int dec = 0;
 140     // searching 17 consecutive lows
 141     for (j = 0; j < 17*lowLen; j++) {
 142       dec -= GraphBuffer[i+j];
 143     }
 144     // searching 7 consecutive highs
 145     for (; j < 17*lowLen + 6*highLen; j++) {
 146       dec += GraphBuffer[i+j];
 147     }
 148     if (dec > max) {
 149       max = dec;
 150       maxPos = i;
 151     }
 152   }
 153
 154   // place a marker in the buffer to visually aid location
 155   // of the start of sync
 156   GraphBuffer[maxPos] = 800;
 157   GraphBuffer[maxPos+1] = -800;
 158
 159   // advance pointer to start of actual data stream (after 16 pre and 8 start bits)
 160   maxPos += 17*lowLen;
 161   maxPos += 6*highLen;
 162
 163   // place a marker in the buffer to visually aid location
 164   // of the end of sync
 165   GraphBuffer[maxPos] = 800;
 166   GraphBuffer[maxPos+1] = -800;
 167
 168   PrintAndLog("actual data bits start at sample %d", maxPos);
 169
 170   PrintAndLog("length %d/%d", highLen, lowLen);
 171
 172   uint8_t bits[1+64+16+8+16];
 173   bits[sizeof(bits)-1] = '\0';
 174
 175   uint32_t shift3 = 0x7e000000, shift2 = 0, shift1 = 0, shift0 = 0;
 176
 177   for (i = 0; i < arraylen(bits)-1; i++) {
 178     int high = 0;
 179     int low = 0;
 180     int j;
 181     for (j = 0; j < lowLen; j++) {
 182       low -= GraphBuffer[maxPos+j];
 183     }
 184     for (j = 0; j < highLen; j++) {
 185       high += GraphBuffer[maxPos+j];
 186     }
 187
 188     if (high > low) {
 189       bits[i] = '1';
 190       maxPos += highLen;
 191       // bitstream arrives lsb first so shift right
 192       shift3 |= (1<<31);
 193     } else {
 194       bits[i] = '.';
 195       maxPos += lowLen;
 196     }
 197
 198     // 128 bit right shift register
 199     shift0 = (shift0>>1) | (shift1 << 31);
 200     shift1 = (shift1>>1) | (shift2 << 31);
 201     shift2 = (shift2>>1) | (shift3 << 31);
 202     shift3 >>= 1;
 203
 204     // place a marker in the buffer between bits to visually aid location
 205     GraphBuffer[maxPos] = 800;
 206     GraphBuffer[maxPos+1] = -800;
 207   }
 208   PrintAndLog("Info: raw tag bits = %s", bits);
 209
 210   TagType = (shift3>>8)&0xff;
 211   if ( TagType != ((shift0>>16)&0xff) ) {
 212     PrintAndLog("Error: start and stop bits do not match!");
 213     return 0;
 214   }
 215   else if (TagType == 0x7e) {
 216     PrintAndLog("Info: Readonly TI tag detected.");
 217     return 0;
 218   }
 219   else if (TagType == 0xfe) {
 220     PrintAndLog("Info: Rewriteable TI tag detected.");
 221
 222     // put 64 bit data into shift1 and shift0
 223     shift0 = (shift0>>24) | (shift1 << 8);
 224     shift1 = (shift1>>24) | (shift2 << 8);
 225
 226     // align 16 bit crc into lower half of shift2
 227     shift2 = ((shift2>>24) | (shift3 << 8)) & 0x0ffff;
 228
 229     // align 16 bit "end bits" or "ident" into lower half of shift3
 230     shift3 >>= 16;
 231
 232     // only 15 bits compare, last bit of ident is not valid
 233     if ( (shift3^shift0)&0x7fff ) {
 234       PrintAndLog("Error: Ident mismatch!");
 235     }
 236     // WARNING the order of the bytes in which we calc crc below needs checking
 237     // i'm 99% sure the crc algorithm is correct, but it may need to eat the
 238     // bytes in reverse or something
 239     // calculate CRC
 240     crc=0;
 241     crc = update_crc16(crc, (shift0)&0xff);
 242     crc = update_crc16(crc, (shift0>>8)&0xff);
 243     crc = update_crc16(crc, (shift0>>16)&0xff);
 244     crc = update_crc16(crc, (shift0>>24)&0xff);
 245     crc = update_crc16(crc, (shift1)&0xff);
 246     crc = update_crc16(crc, (shift1>>8)&0xff);
 247     crc = update_crc16(crc, (shift1>>16)&0xff);
 248     crc = update_crc16(crc, (shift1>>24)&0xff);
 249     PrintAndLog("Info: Tag data = %08X%08X", shift1, shift0);
 250     if (crc != (shift2&0xffff)) {
 251       PrintAndLog("Error: CRC mismatch, calculated %04X, got ^04X", crc, shift2&0xffff);
 252     } else {
 253       PrintAndLog("Info: CRC %04X is good", crc);
 254     }
 255   }
 256   else {
 257     PrintAndLog("Unknown tag type.");
 258     return 0;
 259   }
 260   return 0;
 261 }
 262
 263 // read a TI tag and return its ID
 264 int CmdTIRead(const char *Cmd)
 265 {
 266   UsbCommand c = {CMD_READ_TI_TYPE};
 267   SendCommand(&c);
 268   return 0;
 269 }
 270
 271 // write new data to a r/w TI tag
 272 int CmdTIWrite(const char *Cmd)
 273 {
 274   UsbCommand c = {CMD_WRITE_TI_TYPE};
 275   int res = 0;
 276
 277   res = sscanf(Cmd, "0x%x 0x%x 0x%x ", &c.arg[0], &c.arg[1], &c.arg[2]);
 278   if (res == 2) c.arg[2]=0;
 279   if (res < 2)
 280     PrintAndLog("Please specify the data as two hex strings, optionally the CRC as a third");
 281   else
 282     SendCommand(&c);
 283   return 0;
 284 }
 285
 286 static command_t CommandTable[] =
 287 {
 288   {"help",      CmdHelp,        1, "This help"},
 289   {"demod",     CmdTIDemod,     1, "Demodulate raw bits for TI-type LF tag"},
 290   {"read",      CmdTIRead,      0, "Read and decode a TI 134 kHz tag"},
 291   {"write",     CmdTIWrite,     0, "Write new data to a r/w TI 134 kHz tag"},
 292   {NULL, NULL, 0, NULL}
 293 };
 294
 295 int CmdLFTI(const char *Cmd)
 296 {
 297   CmdsParse(CommandTable, Cmd);
 298   return 0;
 299 }
 300
 301 int CmdHelp(const char *Cmd)
 302 {
 303   CmdsHelp(CommandTable);
 304   return 0;
 305 }