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

   1 // Merlok, 2011, 2012
   2 // people from mifare@nethemba.com, 2010
   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 // mifare commands
   9 //-----------------------------------------------------------------------------
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <pthread.h>
  15 #include "mifarehost.h"
  16 #include "proxmark3.h"
  17 //#include "radixsort.h"
  18 #include <time.h>
  19
  20 // MIFARE
  21 int compar_int(const void * a, const void * b) {
  22         // didn't work: (the result is truncated to 32 bits)
  23         //return (*(uint64_t*)b - *(uint64_t*)a);
  24
  25         // better:
  26         if (*(uint64_t*)b > *(uint64_t*)a) return 1;
  27         if (*(uint64_t*)b < *(uint64_t*)a) return -1;
  28         return 0;
  29
  30         //return (*(uint64_t*)b > *(uint64_t*)a) - (*(uint64_t*)b < *(uint64_t*)a);
  31 }
  32
  33 // Compare 16 Bits out of cryptostate
  34 int Compare16Bits(const void * a, const void * b) {
  35          if ((*(uint64_t*)b & 0x00ff000000ff0000) > (*(uint64_t*)a & 0x00ff000000ff0000)) return 1;
  36          if ((*(uint64_t*)b & 0x00ff000000ff0000) < (*(uint64_t*)a & 0x00ff000000ff0000)) return -1;
  37          return 0;
  38
  39 /*      return
  40                 ((*(uint64_t*)b & 0x00ff000000ff0000) > (*(uint64_t*)a & 0x00ff000000ff0000))
  41                 -
  42                 ((*(uint64_t*)b & 0x00ff000000ff0000) < (*(uint64_t*)a & 0x00ff000000ff0000))
  43                 ;
  44 */
  45 }
  46
  47 typedef
  48         struct {
  49                 union {
  50                         struct Crypto1State *slhead;
  51                         uint64_t *keyhead;
  52                 } head;
  53                 union {
  54                         struct Crypto1State *sltail;
  55                         uint64_t *keytail;
  56                 } tail;
  57                 uint32_t len;
  58                 uint32_t uid;
  59                 uint32_t blockNo;
  60                 uint32_t keyType;
  61                 uint32_t nt;
  62                 uint32_t ks1;
  63         } StateList_t;
  64
  65
  66 // wrapper function for multi-threaded lfsr_recovery32
  67 void* nested_worker_thread(void *arg)
  68 {
  69         struct Crypto1State *p1;
  70         StateList_t *statelist = arg;
  71         statelist->head.slhead = lfsr_recovery32(statelist->ks1, statelist->nt ^ statelist->uid);
  72
  73         for (p1 = statelist->head.slhead; *(uint64_t *)p1 != 0; p1++);
  74
  75         statelist->len = p1 - statelist->head.slhead;
  76         statelist->tail.sltail = --p1;
  77         qsort(statelist->head.slhead, statelist->len, sizeof(uint64_t), Compare16Bits);
  78         return statelist->head.slhead;
  79 }
  80
  81 int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo, uint8_t trgKeyType, uint8_t * resultKey, bool calibrate)
  82 {
  83         uint16_t i;
  84         uint32_t uid;
  85         UsbCommand resp;
  86         StateList_t statelists[2];
  87         struct Crypto1State *p1, *p2, *p3, *p4;
  88
  89         UsbCommand c = {CMD_MIFARE_NESTED, {blockNo + keyType * 0x100, trgBlockNo + trgKeyType * 0x100, calibrate}};
  90         memcpy(c.d.asBytes, key, 6);
  91         clearCommandBuffer();
  92         SendCommand(&c);
  93         if (!WaitForResponseTimeout(CMD_ACK, &resp, 1500)) return -1;
  94
  95         // error during nested
  96         if (resp.arg[0]) return resp.arg[0];
  97
  98         memcpy(&uid, resp.d.asBytes, 4);
  99
 100         for (i = 0; i < 2; i++) {
 101                 statelists[i].blockNo = resp.arg[2] & 0xff;
 102                 statelists[i].keyType = (resp.arg[2] >> 8) & 0xff;
 103                 statelists[i].uid = uid;
 104                 memcpy(&statelists[i].nt,  (void *)(resp.d.asBytes + 4 + i * 8 + 0), 4);
 105                 memcpy(&statelists[i].ks1, (void *)(resp.d.asBytes + 4 + i * 8 + 4), 4);
 106         }
 107
 108         // calc keys
 109         pthread_t thread_id[2];
 110
 111         // create and run worker threads
 112         for (i = 0; i < 2; i++)
 113                 pthread_create(thread_id + i, NULL, nested_worker_thread, &statelists[i]);
 114
 115         // wait for threads to terminate:
 116         for (i = 0; i < 2; i++)
 117                 pthread_join(thread_id[i], (void*)&statelists[i].head.slhead);
 118
 119         // the first 16 Bits of the cryptostate already contain part of our key.
 120         // Create the intersection of the two lists based on these 16 Bits and
 121         // roll back the cryptostate
 122         p1 = p3 = statelists[0].head.slhead;
 123         p2 = p4 = statelists[1].head.slhead;
 124
 125         while (p1 <= statelists[0].tail.sltail && p2 <= statelists[1].tail.sltail) {
 126                 if (Compare16Bits(p1, p2) == 0) {
 127
 128                         struct Crypto1State savestate, *savep = &savestate;
 129                         savestate = *p1;
 130                         while(Compare16Bits(p1, savep) == 0 && p1 <= statelists[0].tail.sltail) {
 131                                 *p3 = *p1;
 132                                 lfsr_rollback_word(p3, statelists[0].nt ^ statelists[0].uid, 0);
 133                                 p3++;
 134                                 p1++;
 135                         }
 136                         savestate = *p2;
 137                         while(Compare16Bits(p2, savep) == 0 && p2 <= statelists[1].tail.sltail) {
 138                                 *p4 = *p2;
 139                                 lfsr_rollback_word(p4, statelists[1].nt ^ statelists[1].uid, 0);
 140                                 p4++;
 141                                 p2++;
 142                         }
 143                 }
 144                 else {
 145                         while (Compare16Bits(p1, p2) == -1) p1++;
 146                         while (Compare16Bits(p1, p2) == 1) p2++;
 147                 }
 148         }
 149
 150         p3->even = 0; p3->odd = 0;
 151         p4->even = 0; p4->odd = 0;
 152         statelists[0].len = p3 - statelists[0].head.slhead;
 153         statelists[1].len = p4 - statelists[1].head.slhead;
 154         statelists[0].tail.sltail=--p3;
 155         statelists[1].tail.sltail=--p4;
 156
 157         // the statelists now contain possible keys. The key we are searching for must be in the
 158         // intersection of both lists. Create the intersection:
 159         qsort(statelists[0].head.keyhead, statelists[0].len, sizeof(uint64_t), compar_int);
 160         qsort(statelists[1].head.keyhead, statelists[1].len, sizeof(uint64_t), compar_int);
 161
 162         uint64_t *p5, *p6, *p7;
 163         p5 = p7 = statelists[0].head.keyhead;
 164         p6 = statelists[1].head.keyhead;
 165
 166         while (p5 <= statelists[0].tail.keytail && p6 <= statelists[1].tail.keytail) {
 167                 if (compar_int(p5, p6) == 0) {
 168                         *p7++ = *p5++;
 169                         p6++;
 170                 }
 171                 else {
 172                         while (compar_int(p5, p6) == -1) p5++;
 173                         while (compar_int(p5, p6) == 1) p6++;
 174                 }
 175         }
 176         statelists[0].len = p7 - statelists[0].head.keyhead;
 177         statelists[0].tail.keytail = --p7;
 178
 179         uint32_t numOfCandidates = statelists[0].len;
 180         if ( numOfCandidates == 0 ) goto out;
 181
 182         memset(resultKey, 0, 6);
 183         uint64_t key64 = 0;
 184
 185         // The list may still contain several key candidates. Test each of them with mfCheckKeys
 186         // uint32_t max_keys = keycnt > (USB_CMD_DATA_SIZE/6) ? (USB_CMD_DATA_SIZE/6) : keycnt;
 187         uint8_t keyBlock[USB_CMD_DATA_SIZE] = {0x00};
 188
 189         for (i = 0; i < numOfCandidates; ++i){
 190                 crypto1_get_lfsr(statelists[0].head.slhead + i, &key64);
 191                 num_to_bytes(key64, 6, keyBlock + i * 6);
 192         }
 193
 194         if (!mfCheckKeys(statelists[0].blockNo, statelists[0].keyType, false, numOfCandidates, keyBlock, &key64)) {
 195                 free(statelists[0].head.slhead);
 196                 free(statelists[1].head.slhead);
 197                 num_to_bytes(key64, 6, resultKey);
 198
 199                 PrintAndLog("UID: %08x target block:%3u key type: %c  -- Found key [%012"llx"]",
 200                         uid,
 201                         (uint16_t)resp.arg[2] & 0xff,
 202                         (resp.arg[2] >> 8) ? 'B' : 'A',
 203                         key64
 204                 );
 205                 return -5;
 206         }
 207
 208 out:
 209         PrintAndLog("UID: %08x target block:%3u key type: %c",
 210                         uid,
 211                         (uint16_t)resp.arg[2] & 0xff,
 212                         (resp.arg[2] >> 8) ? 'B' : 'A'
 213         );
 214
 215         free(statelists[0].head.slhead);
 216         free(statelists[1].head.slhead);
 217         return -4;
 218 }
 219
 220 int mfCheckKeys (uint8_t blockNo, uint8_t keyType, bool clear_trace, uint8_t keycnt, uint8_t * keyBlock, uint64_t * key){
 221
 222         *key = 0;
 223         UsbCommand c = {CMD_MIFARE_CHKKEYS, { (blockNo | (keyType<<8)), clear_trace, keycnt}};
 224         memcpy(c.d.asBytes, keyBlock, 6 * keycnt);
 225         clearCommandBuffer();
 226         SendCommand(&c);
 227         UsbCommand resp;
 228         if (!WaitForResponseTimeout(CMD_ACK,&resp, 2500)) return 1;
 229         if ((resp.arg[0] & 0xff) != 0x01) return 2;
 230         *key = bytes_to_num(resp.d.asBytes, 6);
 231         return 0;
 232 }
 233
 234 // EMULATOR
 235
 236 int mfEmlGetMem(uint8_t *data, int blockNum, int blocksCount) {
 237         UsbCommand c = {CMD_MIFARE_EML_MEMGET, {blockNum, blocksCount, 0}};
 238         clearCommandBuffer();
 239         SendCommand(&c);
 240         UsbCommand resp;
 241         if (!WaitForResponseTimeout(CMD_ACK,&resp,1500)) return 1;
 242         memcpy(data, resp.d.asBytes, blocksCount * 16);
 243         return 0;
 244 }
 245
 246 int mfEmlSetMem(uint8_t *data, int blockNum, int blocksCount) {
 247         return mfEmlSetMem_xt(data, blockNum, blocksCount, 16);
 248 }
 249
 250 int mfEmlSetMem_xt(uint8_t *data, int blockNum, int blocksCount, int blockBtWidth) {
 251         UsbCommand c = {CMD_MIFARE_EML_MEMSET, {blockNum, blocksCount, blockBtWidth}};
 252         memcpy(c.d.asBytes, data, blocksCount * blockBtWidth);
 253
 254         clearCommandBuffer();
 255         SendCommand(&c);
 256         return 0;
 257 }
 258
 259 // "MAGIC" CARD
 260
 261 int mfCSetUID(uint8_t *uid, uint8_t *atqa, uint8_t *sak, uint8_t *oldUID, uint8_t wipecard) {
 262
 263         uint8_t params = MAGIC_SINGLE;
 264         uint8_t block0[16];
 265         memset(block0, 0x00, sizeof(block0));
 266
 267         int old = mfCGetBlock(0, block0, params);
 268         if (old == 0)
 269                 PrintAndLog("old block 0:  %s", sprint_hex(block0, sizeof(block0)));
 270         else
 271                 PrintAndLog("Couldn't get old data. Will write over the last bytes of Block 0.");
 272
 273         // fill in the new values
 274         // UID
 275         memcpy(block0, uid, 4);
 276         // Mifare UID BCC
 277         block0[4] = block0[0]^block0[1]^block0[2]^block0[3];
 278         // mifare classic SAK(byte 5) and ATQA(byte 6 and 7, reversed)
 279         if ( sak != NULL )
 280                 block0[5]=sak[0];
 281
 282         if ( atqa != NULL ) {
 283                 block0[6]=atqa[1];
 284                 block0[7]=atqa[0];
 285         }
 286         PrintAndLog("new block 0:  %s", sprint_hex(block0,16));
 287
 288         if ( wipecard )          params |= MAGIC_WIPE;
 289         if ( oldUID == NULL) params |= MAGIC_UID;
 290
 291         return mfCSetBlock(0, block0, oldUID, params);
 292 }
 293
 294 int mfCSetBlock(uint8_t blockNo, uint8_t *data, uint8_t *uid, uint8_t params) {
 295
 296         uint8_t isOK = 0;
 297         UsbCommand c = {CMD_MIFARE_CSETBLOCK, {params, blockNo, 0}};
 298         memcpy(c.d.asBytes, data, 16);
 299         clearCommandBuffer();
 300         SendCommand(&c);
 301         UsbCommand resp;
 302         if (WaitForResponseTimeout(CMD_ACK, &resp, 1500)) {
 303                 isOK  = resp.arg[0] & 0xff;
 304                 if (uid != NULL)
 305                         memcpy(uid, resp.d.asBytes, 4);
 306                 if (!isOK)
 307                         return 2;
 308         } else {
 309                 PrintAndLog("Command execute timeout");
 310                 return 1;
 311         }
 312         return 0;
 313 }
 314
 315 int mfCGetBlock(uint8_t blockNo, uint8_t *data, uint8_t params) {
 316         uint8_t isOK = 0;
 317         UsbCommand c = {CMD_MIFARE_CGETBLOCK, {params, blockNo, 0}};
 318         clearCommandBuffer();
 319         SendCommand(&c);
 320         UsbCommand resp;
 321         if (WaitForResponseTimeout(CMD_ACK,&resp,1500)) {
 322                 isOK  = resp.arg[0] & 0xff;
 323                 memcpy(data, resp.d.asBytes, 16);
 324                 if (!isOK) return 2;
 325         } else {
 326                 PrintAndLog("Command execute timeout");
 327                 return 1;
 328         }
 329         return 0;
 330 }
 331
 332 // SNIFFER
 333
 334 // constants
 335 static uint8_t trailerAccessBytes[4] = {0x08, 0x77, 0x8F, 0x00};
 336
 337 // variables
 338 char logHexFileName[FILE_PATH_SIZE] = {0x00};
 339 static uint8_t traceCard[4096] = {0x00};
 340 static char traceFileName[FILE_PATH_SIZE] = {0x00};
 341 static int traceState = TRACE_IDLE;
 342 static uint8_t traceCurBlock = 0;
 343 static uint8_t traceCurKey = 0;
 344
 345 struct Crypto1State *traceCrypto1 = NULL;
 346
 347 struct Crypto1State *revstate = NULL;
 348
 349 uint64_t key = 0;
 350 uint32_t ks2 = 0;
 351 uint32_t ks3 = 0;
 352
 353 uint32_t uid = 0;     // serial number
 354 uint32_t nt =0;      // tag challenge
 355 uint32_t nr_enc =0;  // encrypted reader challenge
 356 uint32_t ar_enc =0;  // encrypted reader response
 357 uint32_t at_enc =0;  // encrypted tag response
 358
 359 int isTraceCardEmpty(void) {
 360         return ((traceCard[0] == 0) && (traceCard[1] == 0) && (traceCard[2] == 0) && (traceCard[3] == 0));
 361 }
 362
 363 int isBlockEmpty(int blockN) {
 364         for (int i = 0; i < 16; i++)
 365                 if (traceCard[blockN * 16 + i] != 0) return 0;
 366
 367         return 1;
 368 }
 369
 370 int isBlockTrailer(int blockN) {
 371         return ((blockN & 0x03) == 0x03);
 372 }
 373
 374 int loadTraceCard(uint8_t *tuid) {
 375         FILE * f;
 376         char buf[64] = {0x00};
 377         uint8_t buf8[64] = {0x00};
 378         int i, blockNum;
 379
 380         if (!isTraceCardEmpty())
 381                 saveTraceCard();
 382
 383         memset(traceCard, 0x00, 4096);
 384         memcpy(traceCard, tuid + 3, 4);
 385
 386         FillFileNameByUID(traceFileName, tuid, ".eml", 7);
 387
 388         f = fopen(traceFileName, "r");
 389         if (!f) return 1;
 390
 391         blockNum = 0;
 392
 393         while(!feof(f)){
 394
 395                 memset(buf, 0, sizeof(buf));
 396                 if (fgets(buf, sizeof(buf), f) == NULL) {
 397                         PrintAndLog("File reading error.");
 398                         fclose(f);
 399                         return 2;
 400                 }
 401
 402                 if (strlen(buf) < 32){
 403                         if (feof(f)) break;
 404                         PrintAndLog("File content error. Block data must include 32 HEX symbols");
 405                         fclose(f);
 406                         return 2;
 407                 }
 408                 for (i = 0; i < 32; i += 2)
 409                         sscanf(&buf[i], "%02x", (unsigned int *)&buf8[i / 2]);
 410
 411                 memcpy(traceCard + blockNum * 16, buf8, 16);
 412
 413                 blockNum++;
 414         }
 415         fclose(f);
 416
 417         return 0;
 418 }
 419
 420 int saveTraceCard(void) {
 421         FILE * f;
 422
 423         if ((!strlen(traceFileName)) || (isTraceCardEmpty())) return 0;
 424
 425         f = fopen(traceFileName, "w+");
 426         if ( !f ) return 1;
 427
 428         for (int i = 0; i < 64; i++) {  // blocks
 429                 for (int j = 0; j < 16; j++)  // bytes
 430                         fprintf(f, "%02x", *(traceCard + i * 16 + j));
 431                 fprintf(f,"\n");
 432         }
 433         fclose(f);
 434         return 0;
 435 }
 436
 437 int mfTraceInit(uint8_t *tuid, uint8_t *atqa, uint8_t sak, bool wantSaveToEmlFile) {
 438
 439         if (traceCrypto1)
 440                 crypto1_destroy(traceCrypto1);
 441
 442         traceCrypto1 = NULL;
 443
 444         if (wantSaveToEmlFile)
 445                 loadTraceCard(tuid);
 446
 447         traceCard[4] = traceCard[0] ^ traceCard[1] ^ traceCard[2] ^ traceCard[3];
 448         traceCard[5] = sak;
 449         memcpy(&traceCard[6], atqa, 2);
 450         traceCurBlock = 0;
 451         uid = bytes_to_num(tuid + 3, 4);
 452
 453         traceState = TRACE_IDLE;
 454
 455         return 0;
 456 }
 457
 458 void mf_crypto1_decrypt(struct Crypto1State *pcs, uint8_t *data, int len, bool isEncrypted){
 459         uint8_t bt = 0;
 460         int i;
 461
 462         if (len != 1) {
 463                 for (i = 0; i < len; i++)
 464                         data[i] = crypto1_byte(pcs, 0x00, isEncrypted) ^ data[i];
 465         } else {
 466                 bt = 0;
 467                 bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 0)) << 0;
 468                 bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 1)) << 1;
 469                 bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 2)) << 2;
 470                 bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 3)) << 3;
 471                 data[0] = bt;
 472         }
 473         return;
 474 }
 475
 476 int mfTraceDecode(uint8_t *data_src, int len, bool wantSaveToEmlFile) {
 477
 478         uint8_t data[64];
 479
 480         if (traceState == TRACE_ERROR) return 1;
 481
 482         if (len > 64) {
 483                 traceState = TRACE_ERROR;
 484                 return 1;
 485         }
 486
 487         memcpy(data, data_src, len);
 488         if ((traceCrypto1) && ((traceState == TRACE_IDLE) || (traceState > TRACE_AUTH_OK))) {
 489                 mf_crypto1_decrypt(traceCrypto1, data, len, 0);
 490                 PrintAndLog("dec> %s", sprint_hex(data, len));
 491                 AddLogHex(logHexFileName, "dec> ", data, len);
 492         }
 493
 494         switch (traceState) {
 495         case TRACE_IDLE:
 496                 // check packet crc16!
 497                 if ((len >= 4) && (!CheckCrc14443(CRC_14443_A, data, len))) {
 498                         PrintAndLog("dec> CRC ERROR!!!");
 499                         AddLogLine(logHexFileName, "dec> ", "CRC ERROR!!!");
 500                         traceState = TRACE_ERROR;  // do not decrypt the next commands
 501                         return 1;
 502                 }
 503
 504                 // AUTHENTICATION
 505                 if ((len == 4) && ((data[0] == 0x60) || (data[0] == 0x61))) {
 506                         traceState = TRACE_AUTH1;
 507                         traceCurBlock = data[1];
 508                         traceCurKey = data[0] == 60 ? 1:0;
 509                         return 0;
 510                 }
 511
 512                 // READ
 513                 if ((len ==4) && ((data[0] == 0x30))) {
 514                         traceState = TRACE_READ_DATA;
 515                         traceCurBlock = data[1];
 516                         return 0;
 517                 }
 518
 519                 // WRITE
 520                 if ((len ==4) && ((data[0] == 0xA0))) {
 521                         traceState = TRACE_WRITE_OK;
 522                         traceCurBlock = data[1];
 523                         return 0;
 524                 }
 525
 526                 // HALT
 527                 if ((len ==4) && ((data[0] == 0x50) && (data[1] == 0x00))) {
 528                         traceState = TRACE_ERROR;  // do not decrypt the next commands
 529                         return 0;
 530                 }
 531
 532                 return 0;
 533         break;
 534
 535         case TRACE_READ_DATA:
 536                 if (len == 18) {
 537                         traceState = TRACE_IDLE;
 538
 539                         if (isBlockTrailer(traceCurBlock)) {
 540                                 memcpy(traceCard + traceCurBlock * 16 + 6, data + 6, 4);
 541                         } else {
 542                                 memcpy(traceCard + traceCurBlock * 16, data, 16);
 543                         }
 544                         if (wantSaveToEmlFile) saveTraceCard();
 545                         return 0;
 546                 } else {
 547                         traceState = TRACE_ERROR;
 548                         return 1;
 549                 }
 550         break;
 551
 552         case TRACE_WRITE_OK:
 553                 if ((len == 1) && (data[0] == 0x0a)) {
 554                         traceState = TRACE_WRITE_DATA;
 555
 556                         return 0;
 557                 } else {
 558                         traceState = TRACE_ERROR;
 559                         return 1;
 560                 }
 561         break;
 562
 563         case TRACE_WRITE_DATA:
 564                 if (len == 18) {
 565                         traceState = TRACE_IDLE;
 566
 567                         memcpy(traceCard + traceCurBlock * 16, data, 16);
 568                         if (wantSaveToEmlFile) saveTraceCard();
 569                         return 0;
 570                 } else {
 571                         traceState = TRACE_ERROR;
 572                         return 1;
 573                 }
 574         break;
 575
 576         case TRACE_AUTH1:
 577                 if (len == 4) {
 578                         traceState = TRACE_AUTH2;
 579                         nt = bytes_to_num(data, 4);
 580                         return 0;
 581                 } else {
 582                         traceState = TRACE_ERROR;
 583                         return 1;
 584                 }
 585         break;
 586
 587         case TRACE_AUTH2:
 588                 if (len == 8) {
 589                         traceState = TRACE_AUTH_OK;
 590
 591                         nr_enc = bytes_to_num(data, 4);
 592                         ar_enc = bytes_to_num(data + 4, 4);
 593                         return 0;
 594                 } else {
 595                         traceState = TRACE_ERROR;
 596                         return 1;
 597                 }
 598         break;
 599
 600         case TRACE_AUTH_OK:
 601                 if (len ==4) {
 602                         traceState = TRACE_IDLE;
 603
 604                         at_enc = bytes_to_num(data, 4);
 605
 606                         //  decode key here)
 607                         ks2 = ar_enc ^ prng_successor(nt, 64);
 608                         ks3 = at_enc ^ prng_successor(nt, 96);
 609                         revstate = lfsr_recovery64(ks2, ks3);
 610                         lfsr_rollback_word(revstate, 0, 0);
 611                         lfsr_rollback_word(revstate, 0, 0);
 612                         lfsr_rollback_word(revstate, nr_enc, 1);
 613                         lfsr_rollback_word(revstate, uid ^ nt, 0);
 614
 615                         crypto1_get_lfsr(revstate, &key);
 616                         printf("Key: %012"llx"\n",key);
 617                         AddLogUint64(logHexFileName, "key: ", key);
 618
 619                         int blockShift = ((traceCurBlock & 0xFC) + 3) * 16;
 620                         if (isBlockEmpty((traceCurBlock & 0xFC) + 3)) memcpy(traceCard + blockShift + 6, trailerAccessBytes, 4);
 621
 622                         if (traceCurKey) {
 623                                 num_to_bytes(key, 6, traceCard + blockShift + 10);
 624                         } else {
 625                                 num_to_bytes(key, 6, traceCard + blockShift);
 626                         }
 627                         if (wantSaveToEmlFile) saveTraceCard();
 628
 629                         if (traceCrypto1) {
 630                                 crypto1_destroy(traceCrypto1);
 631                         }
 632
 633                         // set cryptosystem state
 634                         traceCrypto1 = lfsr_recovery64(ks2, ks3);
 635
 636 //      nt = crypto1_word(traceCrypto1, nt ^ uid, 1) ^ nt;
 637
 638         /*      traceCrypto1 = crypto1_create(key); // key in lfsr
 639                 crypto1_word(traceCrypto1, nt ^ uid, 0);
 640                 crypto1_word(traceCrypto1, ar, 1);
 641                 crypto1_word(traceCrypto1, 0, 0);
 642                 crypto1_word(traceCrypto1, 0, 0);*/
 643
 644                         return 0;
 645                 } else {
 646                         traceState = TRACE_ERROR;
 647                         return 1;
 648                 }
 649         break;
 650
 651         default:
 652                 traceState = TRACE_ERROR;
 653                 return 1;
 654         }
 655
 656         return 0;
 657 }
 658
 659 int tryDecryptWord(uint32_t nt, uint32_t ar_enc, uint32_t at_enc, uint8_t *data, int len){
 660         /*
 661         uint32_t nt;      // tag challenge
 662         uint32_t nr_enc;  // encrypted reader challenge
 663         uint32_t ar_enc;  // encrypted reader response
 664         uint32_t at_enc;  // encrypted tag response
 665         */
 666         struct Crypto1State *pcs = NULL;
 667
 668         ks2 = ar_enc ^ prng_successor(nt, 64);
 669         ks3 = at_enc ^ prng_successor(nt, 96);
 670
 671         PrintAndLog("Decrypting data with:");
 672         PrintAndLog("      nt: %08x",nt);
 673         PrintAndLog("  ar_enc: %08x",ar_enc);
 674         PrintAndLog("  at_enc: %08x",at_enc);
 675         PrintAndLog("\nEncrypted data: [%s]", sprint_hex(data,len) );
 676
 677         pcs = lfsr_recovery64(ks2, ks3);
 678         mf_crypto1_decrypt(pcs, data, len, FALSE);
 679         PrintAndLog("Decrypted data: [%s]", sprint_hex(data,len) );
 680         crypto1_destroy(pcs);
 681         return 0;
 682 }