git.zerfleddert.de Git - proxmark3-svn/blob - client/cmdlfem4x.c

   1 #include <stdio.h>
   2 #include "proxusb.h"
   3 #include "ui.h"
   4 #include "graph.h"
   5 #include "cmdparser.h"
   6 #include "cmddata.h"
   7 #include "cmdlf.h"
   8 #include "cmdlfem4x.h"
   9
  10 static int CmdHelp(const char *Cmd);
  11
  12 /* Read the ID of an EM410x tag.
  13  * Format:
  14  *   1111 1111 1           <-- standard non-repeatable header
  15  *   XXXX [row parity bit] <-- 10 rows of 5 bits for our 40 bit tag ID
  16  *   ....
  17  *   CCCC                  <-- each bit here is parity for the 10 bits above in corresponding column
  18  *   0                     <-- stop bit, end of tag
  19  */
  20 int CmdEM410xRead(const char *Cmd)
  21 {
  22   int i, j, clock, header, rows, bit, hithigh, hitlow, first, bit2idx, high, low;
  23   int parity[4];
  24   char id[11];
  25   int retested = 0;
  26   int BitStream[MAX_GRAPH_TRACE_LEN];
  27   high = low = 0;
  28
  29   /* Detect high and lows and clock */
  30   for (i = 0; i < GraphTraceLen; i++)
  31   {
  32     if (GraphBuffer[i] > high)
  33       high = GraphBuffer[i];
  34     else if (GraphBuffer[i] < low)
  35       low = GraphBuffer[i];
  36   }
  37
  38   /* get clock */
  39   clock = GetClock(Cmd, high, 0);
  40
  41   /* parity for our 4 columns */
  42   parity[0] = parity[1] = parity[2] = parity[3] = 0;
  43   header = rows = 0;
  44
  45   /* manchester demodulate */
  46   bit = bit2idx = 0;
  47   for (i = 0; i < (int)(GraphTraceLen / clock); i++)
  48   {
  49     hithigh = 0;
  50     hitlow = 0;
  51     first = 1;
  52
  53     /* Find out if we hit both high and low peaks */
  54     for (j = 0; j < clock; j++)
  55     {
  56       if (GraphBuffer[(i * clock) + j] == high)
  57         hithigh = 1;
  58       else if (GraphBuffer[(i * clock) + j] == low)
  59         hitlow = 1;
  60
  61       /* it doesn't count if it's the first part of our read
  62        because it's really just trailing from the last sequence */
  63       if (first && (hithigh || hitlow))
  64         hithigh = hitlow = 0;
  65       else
  66         first = 0;
  67
  68       if (hithigh && hitlow)
  69         break;
  70     }
  71
  72     /* If we didn't hit both high and low peaks, we had a bit transition */
  73     if (!hithigh || !hitlow)
  74       bit ^= 1;
  75
  76     BitStream[bit2idx++] = bit;
  77   }
  78
  79 retest:
  80   /* We go till 5 before the graph ends because we'll get that far below */
  81   for (i = 1; i < bit2idx - 5; i++)
  82   {
  83     /* Step 2: We have our header but need our tag ID */
  84     if (header == 9 && rows < 10)
  85     {
  86       /* Confirm parity is correct */
  87       if ((BitStream[i] ^ BitStream[i+1] ^ BitStream[i+2] ^ BitStream[i+3]) == BitStream[i+4])
  88       {
  89         /* Read another byte! */
  90         sprintf(id+rows, "%x", (8 * BitStream[i]) + (4 * BitStream[i+1]) + (2 * BitStream[i+2]) + (1 * BitStream[i+3]));
  91         rows++;
  92
  93         /* Keep parity info */
  94         parity[0] ^= BitStream[i];
  95         parity[1] ^= BitStream[i+1];
  96         parity[2] ^= BitStream[i+2];
  97         parity[3] ^= BitStream[i+3];
  98
  99         /* Move 4 bits ahead */
 100         i += 4;
 101       }
 102
 103       /* Damn, something wrong! reset */
 104       else
 105       {
 106         PrintAndLog("Thought we had a valid tag but failed at word %d (i=%d)", rows + 1, i);
 107
 108         /* Start back rows * 5 + 9 header bits, -1 to not start at same place */
 109         i -= 9 + (5 * rows) - 5;
 110
 111         rows = header = 0;
 112       }
 113     }
 114
 115     /* Step 3: Got our 40 bits! confirm column parity */
 116     else if (rows == 10)
 117     {
 118       /* We need to make sure our 4 bits of parity are correct and we have a stop bit */
 119       if (BitStream[i] == parity[0] && BitStream[i+1] == parity[1] &&
 120         BitStream[i+2] == parity[2] && BitStream[i+3] == parity[3] &&
 121         BitStream[i+4] == 0)
 122       {
 123         /* Sweet! */
 124         PrintAndLog("EM410x Tag ID: %s", id);
 125
 126         /* Stop any loops */
 127         return 1;
 128       }
 129
 130       /* Crap! Incorrect parity or no stop bit, start all over */
 131       else
 132       {
 133         rows = header = 0;
 134
 135         /* Go back 59 bits (9 header bits + 10 rows at 4+1 parity) */
 136         i -= 59;
 137       }
 138     }
 139
 140     /* Step 1: get our header */
 141     else if (header < 9)
 142     {
 143       /* Need 9 consecutive 1's */
 144       if (BitStream[i] == 1)
 145         header++;
 146
 147       /* We don't have a header, not enough consecutive 1 bits */
 148       else
 149         header = 0;
 150     }
 151   }
 152
 153   /* if we've already retested after flipping bits, return */
 154   if (retested++)
 155     return 0;
 156
 157   /* if this didn't work, try flipping bits */
 158   for (i = 0; i < bit2idx; i++)
 159     BitStream[i] ^= 1;
 160
 161   goto retest;
 162 }
 163
 164 /* emulate an EM410X tag
 165  * Format:
 166  *   1111 1111 1           <-- standard non-repeatable header
 167  *   XXXX [row parity bit] <-- 10 rows of 5 bits for our 40 bit tag ID
 168  *   ....
 169  *   CCCC                  <-- each bit here is parity for the 10 bits above in corresponding column
 170  *   0                     <-- stop bit, end of tag
 171  */
 172 int CmdEM410xSim(const char *Cmd)
 173 {
 174   int i, n, j, h, binary[4], parity[4];
 175
 176   /* clock is 64 in EM410x tags */
 177   int clock = 64;
 178
 179   /* clear our graph */
 180   ClearGraph(0);
 181
 182   /* write it out a few times */
 183   for (h = 0; h < 4; h++)
 184   {
 185     /* write 9 start bits */
 186     for (i = 0; i < 9; i++)
 187       AppendGraph(0, clock, 1);
 188
 189     /* for each hex char */
 190     parity[0] = parity[1] = parity[2] = parity[3] = 0;
 191     for (i = 0; i < 10; i++)
 192     {
 193       /* read each hex char */
 194       sscanf(&Cmd[i], "%1x", &n);
 195       for (j = 3; j >= 0; j--, n/= 2)
 196         binary[j] = n % 2;
 197
 198       /* append each bit */
 199       AppendGraph(0, clock, binary[0]);
 200       AppendGraph(0, clock, binary[1]);
 201       AppendGraph(0, clock, binary[2]);
 202       AppendGraph(0, clock, binary[3]);
 203
 204       /* append parity bit */
 205       AppendGraph(0, clock, binary[0] ^ binary[1] ^ binary[2] ^ binary[3]);
 206
 207       /* keep track of column parity */
 208       parity[0] ^= binary[0];
 209       parity[1] ^= binary[1];
 210       parity[2] ^= binary[2];
 211       parity[3] ^= binary[3];
 212     }
 213
 214     /* parity columns */
 215     AppendGraph(0, clock, parity[0]);
 216     AppendGraph(0, clock, parity[1]);
 217     AppendGraph(0, clock, parity[2]);
 218     AppendGraph(0, clock, parity[3]);
 219
 220     /* stop bit */
 221     AppendGraph(0, clock, 0);
 222   }
 223
 224   /* modulate that biatch */
 225   CmdManchesterMod("");
 226
 227   /* booyah! */
 228   RepaintGraphWindow();
 229
 230   CmdLFSim("");
 231   return 0;
 232 }
 233
 234 /* Function is equivalent of loread + losamples + em410xread
 235  * looped until an EM410x tag is detected */
 236 int CmdEM410xWatch(const char *Cmd)
 237 {
 238   do
 239   {
 240     CmdLFRead("");
 241     CmdSamples("2000");
 242   } while ( ! CmdEM410xRead(""));
 243   return 0;
 244 }
 245
 246 /* Read the transmitted data of an EM4x50 tag
 247  * Format:
 248  *
 249  *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 250  *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 251  *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 252  *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 253  *  CCCCCCCC                         <- column parity bits
 254  *  0                                <- stop bit
 255  *  LW                               <- Listen Window
 256  *
 257  * This pattern repeats for every block of data being transmitted.
 258  * Transmission starts with two Listen Windows (LW - a modulated
 259  * pattern of 320 cycles each (32/32/128/64/64)).
 260  *
 261  * Note that this data may or may not be the UID. It is whatever data
 262  * is stored in the blocks defined in the control word First and Last
 263  * Word Read values. UID is stored in block 32.
 264  */
 265 int CmdEM4x50Read(const char *Cmd)
 266 {
 267   int i, j, startblock, clock, skip, block, start, end, low, high;
 268   bool complete= false;
 269   int tmpbuff[MAX_GRAPH_TRACE_LEN / 64];
 270   char tmp[6];
 271
 272   high= low= 0;
 273   clock= 64;
 274
 275   /* first get high and low values */
 276   for (i = 0; i < GraphTraceLen; i++)
 277   {
 278     if (GraphBuffer[i] > high)
 279       high = GraphBuffer[i];
 280     else if (GraphBuffer[i] < low)
 281       low = GraphBuffer[i];
 282   }
 283
 284   /* populate a buffer with pulse lengths */
 285   i= 0;
 286   j= 0;
 287   while (i < GraphTraceLen)
 288   {
 289     // measure from low to low
 290     while ((GraphBuffer[i] > low) && (i<GraphTraceLen))
 291       ++i;
 292     start= i;
 293     while ((GraphBuffer[i] < high) && (i<GraphTraceLen))
 294       ++i;
 295     while ((GraphBuffer[i] > low) && (i<GraphTraceLen))
 296       ++i;
 297     if (j>(MAX_GRAPH_TRACE_LEN/64)) {
 298       break;
 299     }
 300     tmpbuff[j++]= i - start;
 301   }
 302
 303   /* look for data start - should be 2 pairs of LW (pulses of 192,128) */
 304   start= -1;
 305   skip= 0;
 306   for (i= 0; i < j - 4 ; ++i)
 307   {
 308     skip += tmpbuff[i];
 309     if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
 310       if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
 311         if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
 312           if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
 313           {
 314             start= i + 3;
 315             break;
 316           }
 317   }
 318   startblock= i + 3;
 319
 320   /* skip over the remainder of the LW */
 321   skip += tmpbuff[i+1]+tmpbuff[i+2];
 322   while (skip < MAX_GRAPH_TRACE_LEN && GraphBuffer[skip] > low)
 323     ++skip;
 324   skip += 8;
 325
 326   /* now do it again to find the end */
 327   end= start;
 328   for (i += 3; i < j - 4 ; ++i)
 329   {
 330     end += tmpbuff[i];
 331     if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
 332       if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
 333         if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
 334           if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
 335           {
 336             complete= true;
 337             break;
 338           }
 339   }
 340
 341   if (start >= 0)
 342     PrintAndLog("Found data at sample: %i",skip);
 343   else
 344   {
 345     PrintAndLog("No data found!");
 346     PrintAndLog("Try again with more samples.");
 347     return 0;
 348   }
 349
 350   if (!complete)
 351   {
 352     PrintAndLog("*** Warning!");
 353     PrintAndLog("Partial data - no end found!");
 354     PrintAndLog("Try again with more samples.");
 355   }
 356
 357   /* get rid of leading crap */
 358   sprintf(tmp,"%i",skip);
 359   CmdLtrim(tmp);
 360
 361   /* now work through remaining buffer printing out data blocks */
 362   block= 0;
 363   i= startblock;
 364   while (block < 6)
 365   {
 366     PrintAndLog("Block %i:", block);
 367     // mandemod routine needs to be split so we can call it for data
 368     // just print for now for debugging
 369     CmdManchesterDemod("i 64");
 370     skip= 0;
 371     /* look for LW before start of next block */
 372     for ( ; i < j - 4 ; ++i)
 373     {
 374       skip += tmpbuff[i];
 375       if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
 376         if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
 377           break;
 378     }
 379     while (GraphBuffer[skip] > low)
 380       ++skip;
 381     skip += 8;
 382     sprintf(tmp,"%i",skip);
 383     CmdLtrim(tmp);
 384     start += skip;
 385     block++;
 386   }
 387   return 0;
 388 }
 389
 390 static command_t CommandTable[] =
 391 {
 392   {"help",        CmdHelp,        1, "This help"},
 393   {"em410xread",  CmdEM410xRead,  1, "[clock rate] -- Extract ID from EM410x tag"},
 394   {"em410xsim",   CmdEM410xSim,   0, "<UID> -- Simulate EM410x tag"},
 395   {"em410xwatch", CmdEM410xWatch, 0, "Watches for EM410x tags"},
 396   {"em4x50read",  CmdEM4x50Read,  1, "Extract data from EM4x50 tag"},
 397   {NULL, NULL, 0, NULL}
 398 };
 399
 400 int CmdLFEM4X(const char *Cmd)
 401 {
 402   CmdsParse(CommandTable, Cmd);
 403   return 0;
 404 }
 405
 406 int CmdHelp(const char *Cmd)
 407 {
 408   CmdsHelp(CommandTable);
 409   return 0;
 410 }