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

#define __STDC_FORMAT_MACROS
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <inttypes.h>
#include "crapto1.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...]\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");
	}

	// 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));
	
	clock_t t1 = clock();
	
	// 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);
  
	t1 = clock() - t1;
	if ( t1 > 0 ) printf("Time : %.0f ticks \n", (float)t1);
	return 0;
}