Merge pull request #237 from marshmellow42/master

[proxmark3-svn] / tools / mfkey / mfkey32.c

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

int main (int argc, char *argv[]) {
  struct Crypto1State *s,*t;
  uint64_t key;     // recovered key
  uint32_t uid;     // serial number
  uint32_t nt;      // tag challenge
  uint32_t nr0_enc; // first encrypted reader challenge
  uint32_t ar0_enc; // first encrypted reader response
  uint32_t nr1_enc; // second encrypted reader challenge
  uint32_t ar1_enc; // second encrypted reader response
  uint32_t ks2;     // keystream used to encrypt reader response

  printf("MIFARE Classic key recovery - based 32 bits of keystream\n");
  printf("Recover key from two 32-bit reader authentication answers only!\n\n");

  if (argc < 7) {
    printf(" syntax: %s <uid> <nt> <{nr_0}> <{ar_0}> <{nr_1}> <{ar_1}>\n\n",argv[0]);
    return 1;
  }

  sscanf(argv[1],"%x",&uid);
  sscanf(argv[2],"%x",&nt);
  sscanf(argv[3],"%x",&nr0_enc);
  sscanf(argv[4],"%x",&ar0_enc);
  sscanf(argv[5],"%x",&nr1_enc);
  sscanf(argv[6],"%x",&ar1_enc);

  printf("Recovering key for:\n");
  printf("    uid: %08x\n",uid);
  printf("     nt: %08x\n",nt);
  printf(" {nr_0}: %08x\n",nr0_enc);
  printf(" {ar_0}: %08x\n",ar0_enc);
  printf(" {nr_1}: %08x\n",nr1_enc);
  printf(" {ar_1}: %08x\n",ar1_enc);

	// 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 = ar0_enc ^ prng_successor(nt, 64);
  printf("  ks2: %08x\n",ks2);

	s = lfsr_recovery32(ar0_enc ^ prng_successor(nt, 64), 0);
  
	for(t = s; t->odd | t->even; ++t) {
		lfsr_rollback_word(t, 0, 0);
		lfsr_rollback_word(t, nr0_enc, 1);
		lfsr_rollback_word(t, uid ^ nt, 0);
		crypto1_get_lfsr(t, &key);
		crypto1_word(t, uid ^ nt, 0);
		crypto1_word(t, nr1_enc, 1);
		if (ar1_enc == (crypto1_word(t, 0, 0) ^ prng_successor(nt, 64))) {
			printf("\nFound Key: [%012" PRIx64 "]\n\n",key);
			break;
		}
	}
  free(s);

  return 0;
}