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 "proxmark3.h"
  15 #include "data.h"
  16 #include "ui.h"
  17 #include "graph.h"
  18 #include "cmdparser.h"
  19 #include "cmdlfti.h"
  20
  21 static int CmdHelp(const char *Cmd);
  22
  23 int CmdTIDemod(const char *Cmd)
  24 {
  25   /* MATLAB as follows:
  26     f_s = 2000000;  % sampling frequency
  27     f_l = 123200;   % low FSK tone
  28     f_h = 134200;   % high FSK tone
  29
  30     T_l = 119e-6;   % low bit duration
  31     T_h = 130e-6;   % high bit duration
  32
  33     l = 2*pi*ones(1, floor(f_s*T_l))*(f_l/f_s);
  34     h = 2*pi*ones(1, floor(f_s*T_h))*(f_h/f_s);
  35
  36     l = sign(sin(cumsum(l)));
  37     h = sign(sin(cumsum(h)));
  38   */
  39
  40   // 2M*16/134.2k = 238
  41   static const int LowTone[] = {
  42     1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
  43     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, -1,
  47     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, -1,
  51     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, -1,
  55     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
  57   };
  58   // 2M*16/123.2k = 260
  59   static const int HighTone[] = {
  60     1, 1, 1, 1, 1, 1, 1, 1,   -1, -1, -1, -1, -1, -1, -1,
  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,
  66     1, 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,
  71     1, 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,
  77     1, 1, 1, 1, 1, 1, 1, 1
  78   };
  79   int lowLen = sizeof(LowTone)/sizeof(int);
  80   int highLen = sizeof(HighTone)/sizeof(int);
  81   int convLen = (highLen>lowLen)?highLen:lowLen;
  82   uint16_t crc;
  83   int i, j, TagType;
  84   int lowSum = 0, highSum = 0;;
  85   int lowTot = 0, highTot = 0;
  86
  87   for (i = 0; i < GraphTraceLen - convLen; i++) {
  88     lowSum = 0;
  89     highSum = 0;;
  90
  91     for (j = 0; j < lowLen; j++) {
  92       lowSum += LowTone[j]*GraphBuffer[i+j];
  93     }
  94     for (j = 0; j < highLen; j++) {
  95       highSum += HighTone[j]*GraphBuffer[i+j];
  96     }
  97     lowSum = abs((100*lowSum) / lowLen);
  98     highSum = abs((100*highSum) / highLen);
  99     lowSum = (lowSum<0)?-lowSum:lowSum;
 100     highSum = (highSum<0)?-highSum:highSum;
 101
 102     GraphBuffer[i] = (highSum << 16) | lowSum;
 103   }
 104
 105   for (i = 0; i < GraphTraceLen - convLen - 16; i++) {
 106     lowTot = 0;
 107     highTot = 0;
 108     // 16 and 15 are f_s divided by f_l and f_h, rounded
 109     for (j = 0; j < 16; j++) {
 110       lowTot += (GraphBuffer[i+j] & 0xffff);
 111     }
 112     for (j = 0; j < 15; j++) {
 113       highTot += (GraphBuffer[i+j] >> 16);
 114     }
 115     GraphBuffer[i] = lowTot - highTot;
 116   }
 117
 118   GraphTraceLen -= (convLen + 16);
 119
 120   RepaintGraphWindow();
 121
 122   // TI tag data format is 16 prebits, 8 start bits, 64 data bits,
 123   // 16 crc CCITT bits, 8 stop bits, 15 end bits
 124
 125   // the 16 prebits are always low
 126   // the 8 start and stop bits of a tag must match
 127   // the start/stop prebits of a ro tag are 01111110
 128   // the start/stop prebits of a rw tag are 11111110
 129   // the 15 end bits of a ro tag are all low
 130   // the 15 end bits of a rw tag match bits 15-1 of the data bits
 131
 132   // Okay, so now we have unsliced soft decisions;
 133   // find bit-sync, and then get some bits.
 134   // look for 17 low bits followed by 6 highs (common pattern for ro and rw tags)
 135   int max = 0, maxPos = 0;
 136   for (i = 0; i < 6000; i++) {
 137     int j;
 138     int dec = 0;
 139     // searching 17 consecutive lows
 140     for (j = 0; j < 17*lowLen; j++) {
 141       dec -= GraphBuffer[i+j];
 142     }
 143     // searching 7 consecutive highs
 144     for (; j < 17*lowLen + 6*highLen; j++) {
 145       dec += GraphBuffer[i+j];
 146     }
 147     if (dec > max) {
 148       max = dec;
 149       maxPos = i;
 150     }
 151   }
 152
 153   // place a marker in the buffer to visually aid location
 154   // of the start of sync
 155   GraphBuffer[maxPos] = 800;
 156   GraphBuffer[maxPos+1] = -800;
 157
 158   // advance pointer to start of actual data stream (after 16 pre and 8 start bits)
 159   maxPos += 17*lowLen;
 160   maxPos += 6*highLen;
 161
 162   // place a marker in the buffer to visually aid location
 163   // of the end of sync
 164   GraphBuffer[maxPos] = 800;
 165   GraphBuffer[maxPos+1] = -800;
 166
 167   PrintAndLog("actual data bits start at sample %d", maxPos);
 168
 169   PrintAndLog("length %d/%d", highLen, lowLen);
 170
 171   uint8_t bits[1+64+16+8+16];
 172   bits[sizeof(bits)-1] = '\0';
 173
 174   uint32_t shift3 = 0x7e000000, shift2 = 0, shift1 = 0, shift0 = 0;
 175
 176   for (i = 0; i < arraylen(bits)-1; i++) {
 177     int high = 0;
 178     int low = 0;
 179     int j;
 180     for (j = 0; j < lowLen; j++) {
 181       low -= GraphBuffer[maxPos+j];
 182     }
 183     for (j = 0; j < highLen; j++) {
 184       high += GraphBuffer[maxPos+j];
 185     }
 186
 187     if (high > low) {
 188       bits[i] = '1';
 189       maxPos += highLen;
 190       // bitstream arrives lsb first so shift right
 191       shift3 |= (1<<31);
 192     } else {
 193       bits[i] = '.';
 194       maxPos += lowLen;
 195     }
 196
 197     // 128 bit right shift register
 198     shift0 = (shift0>>1) | (shift1 << 31);
 199     shift1 = (shift1>>1) | (shift2 << 31);
 200     shift2 = (shift2>>1) | (shift3 << 31);
 201     shift3 >>= 1;
 202
 203     // place a marker in the buffer between bits to visually aid location
 204     GraphBuffer[maxPos] = 800;
 205     GraphBuffer[maxPos+1] = -800;
 206   }
 207   PrintAndLog("Info: raw tag bits = %s", bits);
 208
 209   TagType = (shift3>>8)&0xff;
 210   if ( TagType != ((shift0>>16)&0xff) ) {
 211     PrintAndLog("Error: start and stop bits do not match!");
 212     return 0;
 213   }
 214   else if (TagType == 0x7e) {
 215     PrintAndLog("Info: Readonly TI tag detected.");
 216     return 0;
 217   }
 218   else if (TagType == 0xfe) {
 219     PrintAndLog("Info: Rewriteable TI tag detected.");
 220
 221     // put 64 bit data into shift1 and shift0
 222     shift0 = (shift0>>24) | (shift1 << 8);
 223     shift1 = (shift1>>24) | (shift2 << 8);
 224
 225     // align 16 bit crc into lower half of shift2
 226     shift2 = ((shift2>>24) | (shift3 << 8)) & 0x0ffff;
 227
 228     // align 16 bit "end bits" or "ident" into lower half of shift3
 229     shift3 >>= 16;
 230
 231     // only 15 bits compare, last bit of ident is not valid
 232     if ( (shift3^shift0)&0x7fff ) {
 233       PrintAndLog("Error: Ident mismatch!");
 234     }
 235     // WARNING the order of the bytes in which we calc crc below needs checking
 236     // i'm 99% sure the crc algorithm is correct, but it may need to eat the
 237     // bytes in reverse or something
 238     // calculate CRC
 239     crc=0;
 240     crc = update_crc16(crc, (shift0)&0xff);
 241     crc = update_crc16(crc, (shift0>>8)&0xff);
 242     crc = update_crc16(crc, (shift0>>16)&0xff);
 243     crc = update_crc16(crc, (shift0>>24)&0xff);
 244     crc = update_crc16(crc, (shift1)&0xff);
 245     crc = update_crc16(crc, (shift1>>8)&0xff);
 246     crc = update_crc16(crc, (shift1>>16)&0xff);
 247     crc = update_crc16(crc, (shift1>>24)&0xff);
 248     PrintAndLog("Info: Tag data = %08X%08X", shift1, shift0);
 249     if (crc != (shift2&0xffff)) {
 250       PrintAndLog("Error: CRC mismatch, calculated %04X, got ^04X", crc, shift2&0xffff);
 251     } else {
 252       PrintAndLog("Info: CRC %04X is good", crc);
 253     }
 254   }
 255   else {
 256     PrintAndLog("Unknown tag type.");
 257     return 0;
 258   }
 259   return 0;
 260 }
 261
 262 // read a TI tag and return its ID
 263 int CmdTIRead(const char *Cmd)
 264 {
 265   UsbCommand c = {CMD_READ_TI_TYPE};
 266   SendCommand(&c);
 267   return 0;
 268 }
 269
 270 // write new data to a r/w TI tag
 271 int CmdTIWrite(const char *Cmd)
 272 {
 273   UsbCommand c = {CMD_WRITE_TI_TYPE};
 274   int res = 0;
 275
 276   res = sscanf(Cmd, "0x%"PRIu64"x 0x%"PRIu64"x 0x%"PRIu64"x ", &c.arg[0], &c.arg[1], &c.arg[2]);
 277   if (res == 2) c.arg[2]=0;
 278   if (res < 2)
 279     PrintAndLog("Please specify the data as two hex strings, optionally the CRC as a third");
 280   else
 281     SendCommand(&c);
 282   return 0;
 283 }
 284
 285 static command_t CommandTable[] =
 286 {
 287   {"help",      CmdHelp,        1, "This help"},
 288   {"demod",     CmdTIDemod,     1, "Demodulate raw bits for TI-type LF tag"},
 289   {"read",      CmdTIRead,      0, "Read and decode a TI 134 kHz tag"},
 290   {"write",     CmdTIWrite,     0, "Write new data to a r/w TI 134 kHz tag"},
 291   {NULL, NULL, 0, NULL}
 292 };
 293
 294 int CmdLFTI(const char *Cmd)
 295 {
 296   CmdsParse(CommandTable, Cmd);
 297   return 0;
 298 }
 299
 300 int CmdHelp(const char *Cmd)
 301 {
 302   CmdsHelp(CommandTable);
 303   return 0;
 304 }