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

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

int main (int argc, char *argv[]) 
{
        uint32_t uid;     // serial numDber
        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
        uint64_t key    = 0;                            // recovered key
        struct Crypto1State *revstate;
        uint32_t ks2;                                           // keystream used to encrypt reader response
        uint32_t ks3;                                           // keystream used to encrypt tag response

        printf("MIFARE Classic key recovery - based on 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], "%" SCNx32, &uid);
        sscanf(argv[2], "%" SCNx32, &nt);
        sscanf(argv[3], "%" SCNx32, &nr_enc);
        sscanf(argv[4], "%" SCNx32, &ar_enc);
        sscanf(argv[5], "%" SCNx32, &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");
        }

        printf("\nLFSR successors 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
        ks2 = ar_enc ^ prng_successor(nt, 64);
        ks3 = at_enc ^ prng_successor(nt, 96);
        
        uint64_t start_time = msclock();
        revstate = lfsr_recovery64(ks2, ks3);
        uint64_t time_spent = msclock() - start_time;
        printf("Time spent in lfsr_recovery64(): %1.2f seconds\n", (float)time_spent/1000.0);
        printf("\nKeystream used to generate {ar} and {at}:\n");
        printf("   ks2: %08x\n",ks2);
        printf("   ks3: %08x\n",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);
        crypto1_destroy(revstate);

        printf("\nFound Key: [%012" PRIx64"]\n\n",key);
        
}