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 "cmdlfti.h"
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <inttypes.h>
  16 #include "crc16.h"
  17 #include "comms.h"
  18 #include "ui.h"
  19 #include "graph.h"
  20 #include "cmdparser.h"
  21 #include "util.h"
  22
  23 static int CmdHelp(const char *Cmd);
  24
  25 int CmdTIDemod(const char *Cmd)
  26 {
  27   /* MATLAB as follows:
  28     f_s = 2000000;  % sampling frequency
  29     f_l = 123200;   % low FSK tone
  30     f_h = 134200;   % high FSK tone
  31
  32     T_l = 119e-6;   % low bit duration
  33     T_h = 130e-6;   % high bit duration
  34
  35     l = 2*pi*ones(1, floor(f_s*T_l))*(f_l/f_s);
  36     h = 2*pi*ones(1, floor(f_s*T_h))*(f_h/f_s);
  37
  38     l = sign(sin(cumsum(l)));
  39     h = sign(sin(cumsum(h)));
  40   */
  41
  42   // 2M*16/134.2k = 238
  43   static const int LowTone[] = {
  44     1, 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,
  48     1, 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,
  52     1, 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,
  56     1, 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, -1, -1, -1, -1, -1, -1,
  58     1, 1, 1, 1, 1, 1, 1, 1,    -1, -1
  59   };
  60   // 2M*16/123.2k = 260
  61   static const int HighTone[] = {
  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, -1,
  67     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, -1,
  72     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, -1,
  78     1, 1, 1, 1, 1, 1, 1,      -1, -1, -1, -1, -1, -1, -1,
  79     1, 1, 1, 1, 1, 1, 1, 1
  80   };
  81   int lowLen = sizeof(LowTone)/sizeof(int);
  82   int highLen = sizeof(HighTone)/sizeof(int);
  83   int convLen = (highLen>lowLen)?highLen:lowLen;
  84   uint16_t crc;
  85   int i, j, TagType;
  86   int lowSum = 0, highSum = 0;;
  87   int lowTot = 0, highTot = 0;
  88
  89   for (i = 0; i < GraphTraceLen - convLen; i++) {
  90     lowSum = 0;
  91     highSum = 0;;
  92
  93     for (j = 0; j < lowLen; j++) {
  94       lowSum += LowTone[j]*GraphBuffer[i+j];
  95     }
  96     for (j = 0; j < highLen; j++) {
  97       highSum += HighTone[j]*GraphBuffer[i+j];
  98     }
  99     lowSum = abs((100*lowSum) / lowLen);
 100     highSum = abs((100*highSum) / highLen);
 101     lowSum = (lowSum<0)?-lowSum:lowSum;
 102     highSum = (highSum<0)?-highSum:highSum;
 103
 104     GraphBuffer[i] = (highSum << 16) | lowSum;
 105   }
 106
 107   for (i = 0; i < GraphTraceLen - convLen - 16; i++) {
 108     lowTot = 0;
 109     highTot = 0;
 110     // 16 and 15 are f_s divided by f_l and f_h, rounded
 111     for (j = 0; j < 16; j++) {
 112       lowTot += (GraphBuffer[i+j] & 0xffff);
 113     }
 114     for (j = 0; j < 15; j++) {
 115       highTot += (GraphBuffer[i+j] >> 16);
 116     }
 117     GraphBuffer[i] = lowTot - highTot;
 118   }
 119
 120   GraphTraceLen -= (convLen + 16);
 121
 122   RepaintGraphWindow();
 123
 124   // TI tag data format is 16 prebits, 8 start bits, 64 data bits,
 125   // 16 crc CCITT bits, 8 stop bits, 15 end bits
 126
 127   // the 16 prebits are always low
 128   // the 8 start and stop bits of a tag must match
 129   // the start/stop prebits of a ro tag are 01111110
 130   // the start/stop prebits of a rw tag are 11111110
 131   // the 15 end bits of a ro tag are all low
 132   // the 15 end bits of a rw tag match bits 15-1 of the data bits
 133
 134   // Okay, so now we have unsliced soft decisions;
 135   // find bit-sync, and then get some bits.
 136   // look for 17 low bits followed by 6 highs (common pattern for ro and rw tags)
 137   int max = 0, maxPos = 0;
 138   for (i = 0; i < 6000; i++) {
 139     int j;
 140     int dec = 0;
 141     // searching 17 consecutive lows
 142     for (j = 0; j < 17*lowLen; j++) {
 143       dec -= GraphBuffer[i+j];
 144     }
 145     // searching 7 consecutive highs
 146     for (; j < 17*lowLen + 6*highLen; j++) {
 147       dec += GraphBuffer[i+j];
 148     }
 149     if (dec > max) {
 150       max = dec;
 151       maxPos = i;
 152     }
 153   }
 154
 155   // place a marker in the buffer to visually aid location
 156   // of the start of sync
 157   GraphBuffer[maxPos] = 800;
 158   GraphBuffer[maxPos+1] = -800;
 159
 160   // advance pointer to start of actual data stream (after 16 pre and 8 start bits)
 161   maxPos += 17*lowLen;
 162   maxPos += 6*highLen;
 163
 164   // place a marker in the buffer to visually aid location
 165   // of the end of sync
 166   GraphBuffer[maxPos] = 800;
 167   GraphBuffer[maxPos+1] = -800;
 168
 169   PrintAndLog("actual data bits start at sample %d", maxPos);
 170
 171   PrintAndLog("length %d/%d", highLen, lowLen);
 172
 173   uint8_t bits[1+64+16+8+16];
 174   bits[sizeof(bits)-1] = '\0';
 175
 176   uint32_t shift3 = 0x7e000000, shift2 = 0, shift1 = 0, shift0 = 0;
 177
 178   for (i = 0; i < arraylen(bits)-1; i++) {
 179     int high = 0;
 180     int low = 0;
 181     int j;
 182     for (j = 0; j < lowLen; j++) {
 183       low -= GraphBuffer[maxPos+j];
 184     }
 185     for (j = 0; j < highLen; j++) {
 186       high += GraphBuffer[maxPos+j];
 187     }
 188
 189     if (high > low) {
 190       bits[i] = '1';
 191       maxPos += highLen;
 192       // bitstream arrives lsb first so shift right
 193       shift3 |= (1<<31);
 194     } else {
 195       bits[i] = '.';
 196       maxPos += lowLen;
 197     }
 198
 199     // 128 bit right shift register
 200     shift0 = (shift0>>1) | (shift1 << 31);
 201     shift1 = (shift1>>1) | (shift2 << 31);
 202     shift2 = (shift2>>1) | (shift3 << 31);
 203     shift3 >>= 1;
 204
 205     // place a marker in the buffer between bits to visually aid location
 206     GraphBuffer[maxPos] = 800;
 207     GraphBuffer[maxPos+1] = -800;
 208   }
 209   PrintAndLog("Info: raw tag bits = %s", bits);
 210
 211   TagType = (shift3>>8)&0xff;
 212   if ( TagType != ((shift0>>16)&0xff) ) {
 213     PrintAndLog("Error: start and stop bits do not match!");
 214     return 0;
 215   }
 216   else if (TagType == 0x7e) {
 217     PrintAndLog("Info: Readonly TI tag detected.");
 218     return 0;
 219   }
 220   else if (TagType == 0xfe) {
 221     PrintAndLog("Info: Rewriteable TI tag detected.");
 222
 223     // put 64 bit data into shift1 and shift0
 224     shift0 = (shift0>>24) | (shift1 << 8);
 225     shift1 = (shift1>>24) | (shift2 << 8);
 226
 227     // align 16 bit crc into lower half of shift2
 228     shift2 = ((shift2>>24) | (shift3 << 8)) & 0x0ffff;
 229
 230     // align 16 bit "end bits" or "ident" into lower half of shift3
 231     shift3 >>= 16;
 232
 233     // only 15 bits compare, last bit of ident is not valid
 234     if ( (shift3^shift0)&0x7fff ) {
 235       PrintAndLog("Error: Ident mismatch!");
 236     }
 237     // WARNING the order of the bytes in which we calc crc below needs checking
 238     // i'm 99% sure the crc algorithm is correct, but it may need to eat the
 239     // bytes in reverse or something
 240     // calculate CRC
 241     crc=0;
 242     crc = update_crc16(crc, (shift0)&0xff);
 243     crc = update_crc16(crc, (shift0>>8)&0xff);
 244     crc = update_crc16(crc, (shift0>>16)&0xff);
 245     crc = update_crc16(crc, (shift0>>24)&0xff);
 246     crc = update_crc16(crc, (shift1)&0xff);
 247     crc = update_crc16(crc, (shift1>>8)&0xff);
 248     crc = update_crc16(crc, (shift1>>16)&0xff);
 249     crc = update_crc16(crc, (shift1>>24)&0xff);
 250     PrintAndLog("Info: Tag data = %08X%08X", shift1, shift0);
 251     if (crc != (shift2&0xffff)) {
 252       PrintAndLog("Error: CRC mismatch, calculated %04X, got ^04X", crc, shift2&0xffff);
 253     } else {
 254       PrintAndLog("Info: CRC %04X is good", crc);
 255     }
 256   }
 257   else {
 258     PrintAndLog("Unknown tag type.");
 259     return 0;
 260   }
 261   return 0;
 262 }
 263
 264 // read a TI tag and return its ID
 265 int CmdTIRead(const char *Cmd)
 266 {
 267   UsbCommand c = {CMD_READ_TI_TYPE};
 268   SendCommand(&c);
 269   return 0;
 270 }
 271
 272 // write new data to a r/w TI tag
 273 int CmdTIWrite(const char *Cmd)
 274 {
 275   UsbCommand c = {CMD_WRITE_TI_TYPE};
 276   int res = 0;
 277
 278   res = sscanf(Cmd, "%012" SCNx64 " %012" SCNx64 " %012" SCNx64 "", &c.arg[0], &c.arg[1], &c.arg[2]);
 279
 280   if (res == 2) c.arg[2]=0;
 281   if (res < 2)
 282     PrintAndLog("Please specify the data as two hex strings, optionally the CRC as a third");
 283   else
 284     SendCommand(&c);
 285   return 0;
 286 }
 287
 288 static command_t CommandTable[] =
 289 {
 290   {"help",      CmdHelp,        1, "This help"},
 291   {"demod",     CmdTIDemod,     1, "Demodulate raw bits for TI-type LF tag"},
 292   {"read",      CmdTIRead,      0, "Read and decode a TI 134 kHz tag"},
 293   {"write",     CmdTIWrite,     0, "Write new data to a r/w TI 134 kHz tag"},
 294   {NULL, NULL, 0, NULL}
 295 };
 296
 297 int CmdLFTI(const char *Cmd)
 298 {
 299   CmdsParse(CommandTable, Cmd);
 300   return 0;
 301 }
 302
 303 int CmdHelp(const char *Cmd)
 304 {
 305   CmdsHelp(CommandTable);
 306   return 0;
 307 }