tools/mfkey/mfkey32v2.c

   1 #define __STDC_FORMAT_MACROS
   2 #include <inttypes.h>
   3 #include <stdbool.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include "crapto1/crapto1.h"
   7 #include "util_posix.h"
   8
   9 int main(int argc, char *argv[]) {
  10     struct Crypto1State *s, *t;
  11     uint64_t key;     // recovered key
  12     uint32_t uid;     // serial number
  13     uint32_t nt0;      // tag challenge first
  14     uint32_t nt1;      // tag challenge second
  15     uint32_t nr0_enc; // first encrypted reader challenge
  16     uint32_t ar0_enc; // first encrypted reader response
  17     uint32_t nr1_enc; // second encrypted reader challenge
  18     uint32_t ar1_enc; // second encrypted reader response
  19     uint32_t ks2;     // keystream used to encrypt reader response
  20
  21     printf("MIFARE Classic key recovery - based 32 bits of keystream  VERSION2\n");
  22     printf("Recover key from two 32-bit reader authentication answers only\n");
  23     printf("This version implements Moebius two different nonce solution (like the supercard)\n\n");
  24
  25     if (argc < 8) {
  26         printf("syntax: %s <uid> <nt> <nr_0> <ar_0> <nt1> <nr_1> <ar_1>\n\n", argv[0]);
  27         return 1;
  28     }
  29
  30     sscanf(argv[1], "%x", &uid);
  31     sscanf(argv[2], "%x", &nt0);
  32     sscanf(argv[3], "%x", &nr0_enc);
  33     sscanf(argv[4], "%x", &ar0_enc);
  34     sscanf(argv[5], "%x", &nt1);
  35     sscanf(argv[6], "%x", &nr1_enc);
  36     sscanf(argv[7], "%x", &ar1_enc);
  37
  38     printf("Recovering key for:\n");
  39     printf("    uid: %08x\n", uid);
  40     printf("   nt_0: %08x\n", nt0);
  41     printf(" {nr_0}: %08x\n", nr0_enc);
  42     printf(" {ar_0}: %08x\n", ar0_enc);
  43     printf("   nt_1: %08x\n", nt1);
  44     printf(" {nr_1}: %08x\n", nr1_enc);
  45     printf(" {ar_1}: %08x\n", ar1_enc);
  46
  47     // Generate lfsr succesors of the tag challenge
  48     printf("\nLFSR succesors of the tag challenge:\n");
  49     uint32_t p64 = prng_successor(nt0, 64);
  50     uint32_t p64b = prng_successor(nt1, 64);
  51
  52     printf("  nt': %08x\n", p64);
  53     printf(" nt'': %08x\n", prng_successor(p64, 32));
  54
  55     // Extract the keystream from the messages
  56     printf("\nKeystream used to generate {ar} and {at}:\n");
  57     ks2 = ar0_enc ^ p64;
  58     printf("  ks2: %08x\n", ks2);
  59
  60     s = lfsr_recovery32(ar0_enc ^ p64, 0);
  61
  62     for (t = s; t->odd | t->even; ++t) {
  63         lfsr_rollback_word(t, 0, 0);
  64         lfsr_rollback_word(t, nr0_enc, 1);
  65         lfsr_rollback_word(t, uid ^ nt0, 0);
  66         crypto1_get_lfsr(t, &key);
  67
  68         crypto1_word(t, uid ^ nt1, 0);
  69         crypto1_word(t, nr1_enc, 1);
  70         if (ar1_enc == (crypto1_word(t, 0, 0) ^ p64b)) {
  71             printf("\nFound Key: [%012" PRIx64 "]\n\n", key);
  72             break;
  73         }
  74     }
  75     free(s);
  76     return 0;
  77 }