proxmark3/tools/mfkey/mfkey64.c
2020-05-11 14:46:22 +02:00

102 lines
2.9 KiB
C
Executable File

#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);
}