proxmark3/tools/mf_nonce_brute/mf_trace_brute.c
2021-05-19 10:15:45 +02:00

318 lines
8.8 KiB
C

//
// bruteforce the upper 16bits of a partial key recovered from mf_nonce_brute.
// J-run's original idea was a two part recovery vector with first a offline trace and then online for 2 bytes.
//
// This idea is two use only offline, to recover a nested authentication key.
// Assumption, we get a read/write command after a nested auth, we need 22 bytes of data.
// Iceman, 2021,
//
#define __STDC_FORMAT_MACROS
#include <inttypes.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include "ctype.h"
#include "crapto1/crapto1.h"
#include "protocol.h"
#include "iso14443crc.h"
#include <util_posix.h>
#define AEND "\x1b[0m"
#define _RED_(s) "\x1b[31m" s AEND
#define _GREEN_(s) "\x1b[32m" s AEND
#define _YELLOW_(s) "\x1b[33m" s AEND
#define _CYAN_(s) "\x1b[36m" s AEND
// a global mutex to prevent interlaced printing from different threads
pthread_mutex_t print_lock;
#define ENC_LEN (4 + 16 + 2)
//--------------------- define options here
typedef struct thread_args {
int thread;
int idx;
uint32_t uid;
uint32_t part_key;
uint32_t nt_enc;
uint32_t nr_enc;
uint16_t enc_len;
uint8_t enc[ENC_LEN]; // next encrypted command + a full read/write
} targs;
//------------------------------------------------------------------
uint8_t cmds[8][2] = {
{ISO14443A_CMD_READBLOCK, 18},
{ISO14443A_CMD_WRITEBLOCK, 18},
{MIFARE_AUTH_KEYA, 0},
{MIFARE_AUTH_KEYB, 0},
{MIFARE_CMD_INC, 6},
{MIFARE_CMD_DEC, 6},
{MIFARE_CMD_RESTORE, 6},
{MIFARE_CMD_TRANSFER, 0}
};
static int global_found = 0;
static int thread_count = 2;
static int param_getptr(const char *line, int *bg, int *en, int paramnum) {
int i;
int len = strlen(line);
*bg = 0;
*en = 0;
// skip spaces
while (line[*bg] == ' ' || line[*bg] == '\t')(*bg)++;
if (*bg >= len) {
return 1;
}
for (i = 0; i < paramnum; i++) {
while (line[*bg] != ' ' && line[*bg] != '\t' && line[*bg] != '\0')(*bg)++;
while (line[*bg] == ' ' || line[*bg] == '\t')(*bg)++;
if (line[*bg] == '\0') return 1;
}
*en = *bg;
while (line[*en] != ' ' && line[*en] != '\t' && line[*en] != '\0')(*en)++;
(*en)--;
return 0;
}
static int param_gethex_to_eol(const char *line, int paramnum, uint8_t *data, int maxdatalen, int *datalen) {
int bg, en;
uint32_t temp;
char buf[5] = {0};
if (param_getptr(line, &bg, &en, paramnum)) return 1;
*datalen = 0;
int indx = bg;
while (line[indx]) {
if (line[indx] == '\t' || line[indx] == ' ') {
indx++;
continue;
}
if (isxdigit(line[indx])) {
buf[strlen(buf) + 1] = 0x00;
buf[strlen(buf)] = line[indx];
} else {
// if we have symbols other than spaces and hex
return 1;
}
if (*datalen >= maxdatalen) {
// if we dont have space in buffer and have symbols to translate
return 2;
}
if (strlen(buf) >= 2) {
sscanf(buf, "%x", &temp);
data[*datalen] = (uint8_t)(temp & 0xff);
*buf = 0;
(*datalen)++;
}
indx++;
}
if (strlen(buf) > 0)
//error when not completed hex bytes
return 3;
return 0;
}
static void hex_to_buffer(const uint8_t *buf, const uint8_t *hex_data, const size_t hex_len, const size_t hex_max_len,
const size_t min_str_len, const size_t spaces_between, bool uppercase) {
if (buf == NULL) return;
char *tmp = (char *)buf;
size_t i;
memset(tmp, 0x00, hex_max_len);
size_t max_len = (hex_len > hex_max_len) ? hex_max_len : hex_len;
for (i = 0; i < max_len; ++i, tmp += 2 + spaces_between) {
sprintf(tmp, (uppercase) ? "%02X" : "%02x", (unsigned int) hex_data[i]);
for (size_t j = 0; j < spaces_between; j++)
sprintf(tmp + 2 + j, " ");
}
i *= (2 + spaces_between);
size_t mlen = min_str_len > i ? min_str_len : 0;
if (mlen > hex_max_len)
mlen = hex_max_len;
for (; i < mlen; i++, tmp += 1)
sprintf(tmp, " ");
// remove last space
*tmp = '\0';
return;
}
static char *sprint_hex_inrow_ex(const uint8_t *data, const size_t len, const size_t min_str_len) {
static char buf[100] = {0};
hex_to_buffer((uint8_t *)buf, data, len, sizeof(buf) - 1, min_str_len, 0, true);
return buf;
}
static bool checkValidCmdByte(uint8_t *cmd, uint16_t n) {
bool ok = false;
for (int i = 0; i < 8; ++i) {
if (cmd[0] == cmds[i][0]) {
if (n >= 4)
ok = CheckCrc14443(CRC_14443_A, cmd, 4);
if (cmds[i][1] > 0 && n >= cmds[i][1])
ok = CheckCrc14443(CRC_14443_A, cmd + 4, cmds[i][1]);
if (ok) {
return true;
}
}
}
return false;
}
static void *brute_thread(void *arguments) {
struct thread_args *args = (struct thread_args *) arguments;
uint64_t key = args->part_key;
uint8_t local_enc[args->enc_len];
memcpy(local_enc, args->enc, args->enc_len);
for (uint64_t count = args->idx; count < 0xFFFF; count += thread_count) {
if (__atomic_load_n(&global_found, __ATOMIC_ACQUIRE) == 1) {
break;
}
key |= count << 32;
// Init cipher with key
struct Crypto1State *pcs = crypto1_create(key);
// NESTED decrypt nt with help of new key
crypto1_word(pcs, args->nt_enc ^ args->uid, 1);
crypto1_word(pcs, args->nr_enc, 1);
crypto1_word(pcs, 0, 0);
crypto1_word(pcs, 0, 0);
// decrypt 22 bytes
uint8_t dec[args->enc_len];
for (int i = 0; i < args->enc_len; i++)
dec[i] = crypto1_byte(pcs, 0x00, 0) ^ local_enc[i];
crypto1_destroy(pcs);
if (checkValidCmdByte(dec, args->enc_len) == false) {
continue;
}
__sync_fetch_and_add(&global_found, 1);
// lock this section to avoid interlacing prints from different threats
pthread_mutex_lock(&print_lock);
printf("\nenc: %s\n", sprint_hex_inrow_ex(local_enc, args->enc_len, 0));
printf("dec: %s\n", sprint_hex_inrow_ex(dec, args->enc_len, 0));
printf("\nValid Key found [ " _GREEN_("%012" PRIx64) " ]\n\n", key);
pthread_mutex_unlock(&print_lock);
break;
}
free(args);
return NULL;
}
static int usage(void) {
printf(" syntax: mf_trace_brute <uid> <partial key> <nt enc> <nr enc> [<next_command + 18 bytes>]\n\n");
return 1;
}
int main(int argc, char *argv[]) {
printf("Mifare classic nested auth key recovery Phase 2\n");
if (argc < 3) return usage();
uint32_t uid = 0; // serial number
uint32_t part_key = 0; // last 4 keys of key
uint32_t nt_enc = 0; // noncce tag
uint32_t nr_enc = 0; // nonce reader encrypted
sscanf(argv[1], "%x", &uid);
sscanf(argv[2], "%x", &part_key);
sscanf(argv[3], "%x", &nt_enc);
sscanf(argv[4], "%x", &nr_enc);
int enc_len = 0;
uint8_t enc[ENC_LEN] = {0}; // next encrypted command + a full read/write
param_gethex_to_eol(argv[5], 0, enc, sizeof(enc), &enc_len);
printf("-------------------------------------------------\n");
printf("uid.................. %08x\n", uid);
printf("partial key.......... %08x\n", part_key);
printf("nt enc............... %08x\n", nt_enc);
printf("nr enc............... %08x\n", nr_enc);
printf("next encrypted cmd... %s\n", sprint_hex_inrow_ex(enc, enc_len, 0));
uint64_t t1 = msclock();
#if !defined(_WIN32) || !defined(__WIN32__)
thread_count = sysconf(_SC_NPROCESSORS_CONF);
if (thread_count < 2)
thread_count = 2;
#endif /* _WIN32 */
printf("\nBruteforce using %d threads to find upper 16bits of key\n", thread_count);
pthread_t threads[thread_count];
// create a mutex to avoid interlacing print commands from our different threads
pthread_mutex_init(&print_lock, NULL);
// threads
for (int i = 0; i < thread_count; ++i) {
struct thread_args *a = calloc(1, sizeof(struct thread_args));
a->thread = i;
a->idx = i;
a->uid = uid;
a->part_key = part_key;
a->nt_enc = nt_enc;
a->nr_enc = nr_enc;
a->enc_len = enc_len;
memcpy(a->enc, enc, enc_len);
pthread_create(&threads[i], NULL, brute_thread, (void *)a);
}
// wait for threads to terminate:
for (int i = 0; i < thread_count; ++i)
pthread_join(threads[i], NULL);
if (global_found == false) {
printf("\nFailed to find a key\n\n");
}
t1 = msclock() - t1;
if (t1 > 0)
printf("execution time " _YELLOW_("%.2f") " sec\n", (float)t1 / 1000.0);
// clean up mutex
pthread_mutex_destroy(&print_lock);
return 0;
}