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proxmark3/armsrc/hitag2.c

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//-----------------------------------------------------------------------------
// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// See LICENSE.txt for the text of the license.
//-----------------------------------------------------------------------------
#include "hitag2.h"
#include "hitag2/hitag2_crypto.h"
#include "string.h"
#include "proxmark3_arm.h"
#include "cmd.h"
#include "BigBuf.h"
#include "fpgaloader.h"
#include "ticks.h"
#include "dbprint.h"
#include "util.h"
#include "lfadc.h"
#include "lfsampling.h"
#include "lfdemod.h"
#include "commonutil.h"
#include "appmain.h"
#include "protocols.h"
#define test_bit(data, i) (*(data + (i/8)) >> (7-(i % 8))) & 1
#define set_bit(data, i) *(data + (i/8)) |= (1 << (7-(i % 8)))
#define clear_bit(data, i) *(data + (i/8)) &= ~(1 << (7-(i % 8)))
#define flip_bit(data, i) *(data + (i/8)) ^= (1 << (7-(i % 8)))
// Successful crypto auth
static bool bCrypto;
// Is in auth stage
static bool bAuthenticating;
// Successful password auth
static bool bSelecting;
static bool bCollision;
static bool bPwd;
static bool bSuccessful;
/*
Password Mode : 0x06 - 0000 0110
Crypto Mode : 0x0E - 0000 1110
Public Mode A : 0x02 - 0000 0010
Public Mode B : 0x00 - 0000 0000
Public Mode C : 0x04 - 0000 0100
*/
static hitag2_t tag = {
.state = TAG_STATE_RESET,
.sectors = { // Password mode: | Crypto mode:
[0] = { 0x02, 0x4e, 0x02, 0x20}, // UID | UID
[1] = { 0x4d, 0x49, 0x4b, 0x52}, // Password RWD | 32 bit LSB key
[2] = { 0x20, 0xf0, 0x4f, 0x4e}, // Reserved | 16 bit MSB key, 16 bit reserved
[3] = { 0x06, 0xaa, 0x48, 0x54}, // Configuration, password TAG | Configuration, password TAG
[4] = { 0x46, 0x5f, 0x4f, 0x4b}, // Data: F_OK
[5] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
[6] = { 0xaa, 0xaa, 0xaa, 0xaa}, // Data: ....
[7] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
[8] = { 0x00, 0x00, 0x00, 0x00}, // RSK Low
[9] = { 0x00, 0x00, 0x00, 0x00}, // RSK High
[10] = { 0x00, 0x00, 0x00, 0x00}, // RCF
[11] = { 0x00, 0x00, 0x00, 0x00}, // SYNC
// up to index 15 reserved for HITAG 1/HITAG S public data
},
};
static enum {
WRITE_STATE_START = 0x0,
WRITE_STATE_PAGENUM_WRITTEN,
WRITE_STATE_PROG
} writestate;
// ToDo: define a meaningful maximum size for auth_table. The bigger this is, the lower will be the available memory for traces.
// Historically it used to be FREE_BUFFER_SIZE, which was 2744.
#define AUTH_TABLE_LENGTH 2744
static uint8_t *auth_table;
static size_t auth_table_pos = 0;
static size_t auth_table_len = AUTH_TABLE_LENGTH;
static uint8_t password[4];
static uint8_t NrAr[8];
static uint8_t key[8];
static uint8_t writedata[4];
static uint8_t logdata_0[4], logdata_1[4];
static uint8_t nonce[4];
static uint8_t key_no;
static uint64_t cipher_state;
static int16_t blocknr;
static size_t flipped_bit = 0;
static uint32_t byte_value = 0;
static void hitag2_reset(void) {
tag.state = TAG_STATE_RESET;
tag.crypto_active = 0;
}
static void hitag2_init(void) {
hitag2_reset();
}
// Sam7s has several timers, we will use the source TIMER_CLOCK1 (aka AT91C_TC_CLKS_TIMER_DIV1_CLOCK)
// TIMER_CLOCK1 = MCK/2, MCK is running at 48 MHz, Timer is running at 48/2 = 24 MHz
// Hitag units (T0) have duration of 8 microseconds (us), which is 1/125000 per second (carrier)
// T0 = TIMER_CLOCK1 / 125000 = 192
#ifndef HITAG_T0
#define HITAG_T0 192
#endif
#define HITAG_FRAME_LEN 20
#define HITAG_FRAME_BIT_COUNT (8 * HITAG_FRAME_LEN)
#define HITAG_T_STOP 36 /* T_EOF should be > 36 */
#define HITAG_T_LOW 6 /* T_LOW should be 4..10 */
#define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */
#define HITAG_T_0 20 /* T[0] should be 18..22 */
#define HITAG_T_1_MIN 25 /* T[1] should be 26..30 */
#define HITAG_T_1 30 /* T[1] should be 26..30 */
#define HITAG_T_EOF 80 /* T_EOF should be > 36 and must be larger than HITAG_T_TAG_CAPTURE_FOUR_HALF */
#define HITAG_T_WAIT_1_MIN 199 /* T_wresp should be 199..206 */
#define HITAG_T_WAIT_2_MIN 90 /* T_wait2 should be at least 90 */
#define HITAG_T_WAIT_MAX 300 /* bit more than HITAG_T_WAIT_1 + HITAG_T_WAIT_2 */
#define HITAG_T_PROG 614
#define HITAG_T_WAIT_POWERUP 313 /* transponder internal powerup time is 312.5 */
#define HITAG_T_WAIT_START_AUTH_MAX 232 /* transponder waiting time to receive the START_AUTH command is 232.5, then it enters public mode */
#define HITAG_T_TAG_ONE_HALF_PERIOD 10
#define HITAG_T_TAG_TWO_HALF_PERIOD 25
#define HITAG_T_TAG_THREE_HALF_PERIOD 41
#define HITAG_T_TAG_FOUR_HALF_PERIOD 57
#define HITAG_T_TAG_HALF_PERIOD 16
#define HITAG_T_TAG_FULL_PERIOD 32
#define HITAG_T_TAG_CAPTURE_ONE_HALF 13
#define HITAG_T_TAG_CAPTURE_TWO_HALF 25
#define HITAG_T_TAG_CAPTURE_THREE_HALF 41
#define HITAG_T_TAG_CAPTURE_FOUR_HALF 57
#define HT2_MAX_NRSZ ((8 * HITAG_FRAME_LEN + 5) * 2)
/*
// sim
static void hitag_send_bit(int bit, bool ledcontrol) {
if (ledcontrol) LED_A_ON();
// Reset clock for the next bit
AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
// Fixed modulation, earlier proxmark version used inverted signal
// check datasheet if reader uses BiPhase?
if (bit == 0) {
// Manchester: Unloaded, then loaded |__--|
LOW(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < HITAG_T0 * HITAG_T_TAG_HALF_PERIOD);
HIGH(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < HITAG_T0 * HITAG_T_TAG_FULL_PERIOD);
} else {
// Manchester: Loaded, then unloaded |--__|
HIGH(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < HITAG_T0 * HITAG_T_TAG_HALF_PERIOD);
LOW(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < HITAG_T0 * HITAG_T_TAG_FULL_PERIOD);
}
if (ledcontrol) LED_A_OFF();
}
// sim
static void hitag_send_frame(const uint8_t *frame, size_t frame_len) {
// SOF - send start of frame
hitag_send_bit(1);
hitag_send_bit(1);
hitag_send_bit(1);
hitag_send_bit(1);
hitag_send_bit(1);
// Send the content of the frame
for (size_t i = 0; i < frame_len; i++) {
hitag_send_bit((frame[i / 8] >> (7 - (i % 8))) & 1);
}
// Drop the modulation
LOW(GPIO_SSC_DOUT);
}
*/
// sim
static void hitag2_handle_reader_command(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
uint8_t rx_air[HITAG_FRAME_LEN];
// Copy the (original) received frame how it is send over the air
memcpy(rx_air, rx, nbytes(rxlen));
if (tag.crypto_active) {
ht2_hitag2_cipher_transcrypt(&(tag.cs), rx, rxlen / 8, rxlen % 8);
}
// Reset the transmission frame length
*txlen = 0;
// Try to find out which command was send by selecting on length (in bits)
switch (rxlen) {
// Received 11000 from the reader, request for UID, send UID
case 5: {
// Always send over the air in the clear plaintext mode
if (rx_air[0] != HITAG2_START_AUTH) {
// Unknown frame ?
return;
}
*txlen = 32;
memcpy(tx, tag.sectors[0], 4);
tag.crypto_active = 0;
}
break;
// Read/Write command: ..xx x..y yy with yyy == ~xxx, xxx is sector number
case 10: {
uint16_t sector = (~(((rx[0] << 2) & 0x04) | ((rx[1] >> 6) & 0x03)) & 0x07);
// Verify complement of sector index
if (sector != ((rx[0] >> 3) & 0x07)) {
DBG DbpString("Transmission error (read/write)");
return;
}
switch (rx[0] & 0xC6) {
// Read command: 11xx x00y
case HITAG2_READ_PAGE: {
memcpy(tx, tag.sectors[sector], 4);
*txlen = 32;
break;
}
// Inverted Read command: 01xx x10y
case HITAG2_READ_PAGE_INVERTED: {
for (size_t i = 0; i < 4; i++) {
tx[i] = tag.sectors[sector][i] ^ 0xff;
}
*txlen = 32;
break;
}
// Write command: 10xx x01y
case HITAG2_WRITE_PAGE: {
// Prepare write, acknowledge by repeating command
memcpy(tx, rx, nbytes(rxlen));
*txlen = rxlen;
tag.active_sector = sector;
tag.state = TAG_STATE_WRITING;
break;
}
// Unknown command
default: {
DBG Dbprintf("Unknown command: %02x %02x", rx[0], rx[1]);
return;
}
}
}
break;
// Writing data or Reader password
case 32: {
if (tag.state == TAG_STATE_WRITING) {
// These are the sector contents to be written. We don't have to do anything else.
memcpy(tag.sectors[tag.active_sector], rx, nbytes(rxlen));
tag.state = TAG_STATE_RESET;
return;
} else {
// Received RWD password, respond with configuration and our password
if (memcmp(rx, tag.sectors[1], 4) != 0) {
DBG DbpString("Reader password is wrong");
return;
}
*txlen = 32;
memcpy(tx, tag.sectors[3], 4);
}
}
break;
// Received RWD authentication challenge and response
case 64: {
// Store the authentication attempt
if (auth_table_len < (AUTH_TABLE_LENGTH - 8)) {
memcpy(auth_table + auth_table_len, rx, 8);
auth_table_len += 8;
}
// Reset the cipher state
ht2_hitag2_cipher_reset(&tag, rx);
// Check if the authentication was correct
if (!ht2_hitag2_cipher_authenticate(&(tag.cs), rx + 4)) {
// The reader failed to authenticate, do nothing
DBG Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x Failed!", rx[0], rx[1], rx[2], rx[3], rx[4], rx[5], rx[6], rx[7]);
return;
}
// Activate encryption algorithm for all further communication
tag.crypto_active = 1;
// Use the tag password as response
memcpy(tx, tag.sectors[3], 4);
*txlen = 32;
}
break;
}
// LogTraceBits(rx, rxlen, 0, 0, false);
// LogTraceBits(tx, txlen, 0, 0, true);
if (tag.crypto_active) {
ht2_hitag2_cipher_transcrypt(&(tag.cs), tx, *txlen / 8, *txlen % 8);
}
}
// reader/writer
// returns how long it took
static uint32_t hitag_reader_send_bit(int bit) {
// Binary pulse length modulation (BPLM) is used to encode the data stream
// This means that a transmission of a one takes longer than that of a zero
// Enable modulation, which means, drop the field
lf_modulation(true);
// Wait for 4-10 times the carrier period
lf_wait_periods(HITAG_T_LOW); // wait for 4-10 times the carrier period
uint32_t wait = HITAG_T_LOW;
// Disable modulation, just activates the field again
lf_modulation(false);
if (bit == 0) {
// Zero bit: |_-|
lf_wait_periods(HITAG_T_0 - HITAG_T_LOW); // wait for 18-22 times the carrier period
wait += HITAG_T_0 - HITAG_T_LOW;
} else {
// One bit: |_--|
lf_wait_periods(HITAG_T_1 - HITAG_T_LOW); // wait for 26-32 times the carrier period
wait += HITAG_T_1 - HITAG_T_LOW;
}
return wait;
}
// reader / writer commands
// frame_len is in number of bits?
static uint32_t hitag_reader_send_frame(const uint8_t *frame, size_t frame_len) {
WDT_HIT();
uint32_t wait = 0;
// Send the content of the frame
for (size_t i = 0; i < frame_len; i++) {
wait += hitag_reader_send_bit((frame[i / 8] >> (7 - (i % 8))) & 1);
}
// Send EOF
// Enable modulation, which means, drop the field
lf_modulation(true);
// Wait for 4-10 times the carrier period
lf_wait_periods(HITAG_T_LOW);
wait += HITAG_T_LOW;
// Disable modulation, just activates the field again
lf_modulation(false);
// t_stop, high field for stop condition (> 36)
lf_wait_periods(HITAG_T_STOP);
wait += HITAG_T_STOP;
WDT_HIT();
return wait;
}
// reader / writer commands
// frame_len is in number of bits?
static uint32_t hitag_reader_send_framebits(const uint8_t *frame, size_t frame_len) {
WDT_HIT();
uint32_t wait = 0;
// Send the content of the frame
for (size_t i = 0; i < frame_len; i++) {
wait += hitag_reader_send_bit(frame[i]);
}
// Send EOF
// Enable modulation, which means, drop the field
// set GPIO_SSC_DOUT to HIGH
lf_modulation(true);
// Wait for 4-10 times the carrier period
lf_wait_periods(HITAG_T_LOW);
wait += HITAG_T_LOW;
// Disable modulation, just activates the field again
// set GPIO_SSC_DOUT to LOW
lf_modulation(false);
// t_stop, high field for stop condition (> 36)
lf_wait_periods(HITAG_T_STOP);
wait += HITAG_T_STOP;
WDT_HIT();
return wait;
}
static uint8_t hitag_crc(uint8_t *data, size_t n) {
uint8_t crc = 0xFF;
for (size_t i = 0; i < ((n + 7) / 8); i++) {
crc ^= *(data + i);
uint8_t bit = n < (8 * (i + 1)) ? (n % 8) : 8;
while (bit--) {
if (crc & 0x80) {
crc <<= 1;
crc ^= 0x1D;
} else {
crc <<= 1;
}
}
}
return crc;
}
/*
void fix_ac_decoding(uint8_t *input, size_t len) {
// Reader routine tries to decode AC data after Manchester decoding
// AC has double the bitrate, extract data from bit-pairs
uint8_t temp[len / 16];
memset(temp, 0, sizeof(temp));
for (size_t i = 1; i < len; i += 2) {
if (test_bit(input, i) && test_bit(input, (i + 1))) {
set_bit(temp, (i / 2));
}
}
memcpy(input, temp, sizeof(temp));
}
*/
// looks at number of received bits.
// 0 = collision?
// 32 = good response
static bool hitag1_plain(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool hitag_s) {
*txlen = 0;
switch (rxlen) {
case 0: {
// retry waking up card
/*tx[0] = 0xb0; // Rev 3.0*/
tx[0] = HITAG1_SET_CC; // Rev 2.0
*txlen = 5;
if (!bCollision) blocknr--;
if (blocknr < 0) {
blocknr = 0;
}
if (!hitag_s) {
if (blocknr > 1 && blocknr < 31) {
blocknr = 31;
}
}
bCollision = true;
return true;
}
case 32: {
uint8_t crc;
if (bCollision) {
// Select card by serial from response
tx[0] = HITAG1_SELECT | rx[0] >> 5;
tx[1] = rx[0] << 3 | rx[1] >> 5;
tx[2] = rx[1] << 3 | rx[2] >> 5;
tx[3] = rx[2] << 3 | rx[3] >> 5;
tx[4] = rx[3] << 3;
crc = hitag_crc(tx, 37);
tx[4] |= crc >> 5;
tx[5] = crc << 3;
*txlen = 45;
bCollision = false;
} else {
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
if (!hitag_s) {
if (blocknr > 1 && blocknr < 31) {
blocknr = 31;
}
}
if (blocknr > 63) {
DbpString("Read successful!");
*txlen = 0;
bSuccessful = true;
return false;
}
// read next page of card until done
Dbprintf("Reading page %02u", blocknr);
tx[0] = HITAG1_RDPPAGE | blocknr >> 4; // RDPPAGE
tx[1] = blocknr << 4;
crc = hitag_crc(tx, 12);
tx[1] |= crc >> 4;
tx[2] = crc << 4;
*txlen = 20;
}
}
break;
default: {
Dbprintf("Unknown frame length: %d", rxlen);
return false;
}
break;
}
return true;
}
static bool hitag1_authenticate(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
uint8_t crc;
*txlen = 0;
switch (rxlen) {
case 0: {
// retry waking up card
/*tx[0] = 0xb0; // Rev 3.0*/
tx[0] = HITAG1_SELECT; // Rev 2.0
*txlen = 5;
if (bCrypto && byte_value <= 0xff) {
// to retry
bCrypto = false;
}
if (!bCollision) blocknr--;
if (blocknr < 0) {
blocknr = 0;
}
bCollision = true;
// will receive 32-bit UID
}
break;
case 2: {
if (bAuthenticating) {
// received Auth init ACK, send nonce
// TODO Roel, bit-manipulation goes here
/*nonce[0] = 0x2d;*/
/*nonce[1] = 0x74;*/
/*nonce[2] = 0x80;*/
/*nonce[3] = 0xa5;*/
nonce[0] = byte_value;
byte_value++;
/*set_bit(nonce,flipped_bit);*/
memcpy(tx, nonce, 4);
*txlen = 32;
// will receive 32 bit encrypted Logdata
} else if (bCrypto) {
// authed, start reading
tx[0] = HITAG1_RDCPAGE | blocknr >> 4; // RDCPAGE
tx[1] = blocknr << 4;
crc = hitag_crc(tx, 12);
tx[1] |= crc >> 4;
tx[2] = crc << 4;
*txlen = 20;
// will receive 32-bit encrypted page
}
}
break;
case 32: {
if (bCollision) {
// Select card by serial from response
tx[0] = HITAG1_SELECT | rx[0] >> 5;
tx[1] = rx[0] << 3 | rx[1] >> 5;
tx[2] = rx[1] << 3 | rx[2] >> 5;
tx[3] = rx[2] << 3 | rx[3] >> 5;
tx[4] = rx[3] << 3;
crc = hitag_crc(tx, 37);
tx[4] |= crc >> 5;
tx[5] = crc << 3;
*txlen = 45;
bCollision = false;
bSelecting = true;
// will receive 32-bit configuration page
} else if (bSelecting) {
// Initiate auth
tx[0] = HITAG1_WRCPAGE | (key_no); // WRCPAGE
tx[1] = blocknr << 4;
crc = hitag_crc(tx, 12);
tx[1] |= crc >> 4;
tx[2] = crc << 4;
*txlen = 20;
bSelecting = false;
bAuthenticating = true;
// will receive 2-bit ACK
} else if (bAuthenticating) {
// received 32-bit logdata 0
// TODO decrypt logdata 0, verify against logdata_0
memcpy(tag.sectors[0], rx, 4);
memcpy(tag.sectors[1], tx, 4);
Dbprintf("%02x%02x%02x%02x %02x%02x%02x%02x", rx[0], rx[1], rx[2], rx[3], tx[0], tx[1], tx[2], tx[3]);
// TODO replace with secret data stream
// TODO encrypt logdata_1
memcpy(tx, logdata_1, 4);
*txlen = 32;
bAuthenticating = false;
bCrypto = true;
// will receive 2-bit ACK
} else if (bCrypto) {
// received 32-bit encrypted page
// TODO decrypt rx
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
if (blocknr > 63) {
DbpString("Read successful!");
bSuccessful = true;
return false;
}
// TEST
Dbprintf("Successfully authenticated with logdata:");
Dbhexdump(4, logdata_1, false);
bSuccessful = true;
return false;
/*
// read next page of card until done
tx[0] = HITAG1_RDCPAGE | blocknr >> 4; // RDCPAGE
tx[1] = blocknr << 4;
crc = hitag_crc(tx, 12);
tx[1] |= crc >> 4;
tx[2] = crc << 4;
*txlen = 20;
*/
}
}
break;
default: {
Dbprintf("Unknown frame length: %d", rxlen);
return false;
}
break;
}
return true;
}
//-----------------------------------------------------------------------------
// Hitag 2 operations
//-----------------------------------------------------------------------------
static bool hitag2_write_page(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
switch (writestate) {
case WRITE_STATE_START: {
*txlen = 10;
tx[0] = HITAG2_WRITE_PAGE | (blocknr << 3) | ((blocknr ^ 7) >> 2);
tx[1] = ((blocknr ^ 7) << 6);
writestate = WRITE_STATE_PAGENUM_WRITTEN;
break;
}
case WRITE_STATE_PAGENUM_WRITTEN: {
// Check if page number was received correctly
if ((rxlen == 10)
&& (rx[0] == (HITAG2_WRITE_PAGE | (blocknr << 3) | ((blocknr ^ 7) >> 2)))
&& (rx[1] == (((blocknr & 0x3) ^ 0x3) << 6))) {
*txlen = 32;
memset(tx, 0, HITAG_FRAME_LEN);
memcpy(tx, writedata, 4);
writestate = WRITE_STATE_PROG;
} else {
Dbprintf("hitag2_write_page: Page number was not received correctly: rxlen %d rx %02x%02x%02x%02x"
, rxlen
, rx[0], rx[1], rx[2], rx[3]
);
bSuccessful = false;
return false;
}
break;
}
case WRITE_STATE_PROG: {
if (rxlen == 0) {
bSuccessful = true;
} else {
bSuccessful = false;
Dbprintf("hitag2_write_page: unexpected rx data (%d) after page write", rxlen);
}
return false;
}
default: {
Dbprintf("hitag2_write_page: Unknown state " _RED_("%d"), writestate);
bSuccessful = false;
return false;
}
}
return true;
}
static bool hitag2_password(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool write) {
// Reset the transmission frame length
*txlen = 0;
if (bPwd && (bAuthenticating == false) && write) {
SpinDelay(2);
if (hitag2_write_page(rx, rxlen, tx, txlen) == false) {
return false;
}
} else {
// Try to find out which command was send by selecting on length (in bits)
switch (rxlen) {
// No answer, try to resurrect
case 0: {
// Stop if there is no answer (after sending password)
if (bPwd) {
DBG DbpString("Password failed!");
return false;
}
*txlen = 5;
memcpy(tx, "\xC0", nbytes(*txlen));
}
break;
// Received UID, tag password
case 32: {
// stage 1, got UID
if (bPwd == false) {
bPwd = true;
bAuthenticating = true;
memcpy(tx, password, 4);
*txlen = 32;
} else {
// stage 2, got config byte+password TAG, discard as will read later
if (bAuthenticating) {
bAuthenticating = false;
if (write) {
if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
return false;
}
break;
}
}
// stage 2+, got data block
else {
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
}
if (blocknr > 7) {
bSuccessful = true;
return false;
}
*txlen = 10;
tx[0] = HITAG2_READ_PAGE | (blocknr << 3) | ((blocknr ^ 7) >> 2);
tx[1] = ((blocknr ^ 7) << 6);
}
}
break;
// Unexpected response
default: {
DBG Dbprintf("Unknown frame length: " _RED_("%d"), rxlen);
return false;
}
break;
}
}
return true;
}
static bool hitag2_crypto(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool write) {
// Reset the transmission frame length
*txlen = 0;
if (bCrypto) {
ht2_hitag2_cipher_transcrypt(&cipher_state, rx, rxlen / 8, rxlen % 8);
}
if (bCrypto && (bAuthenticating == false) && write) {
SpinDelay(2);
if (hitag2_write_page(rx, rxlen, tx, txlen) == false) {
return false;
}
} else {
// Try to find out which command was send by selecting on length (in bits)
switch (rxlen) {
// No answer, try to resurrect
case 0: {
// Stop if there is no answer while we are in crypto mode (after sending NrAr)
if (bCrypto) {
// Failed during authentication
if (bAuthenticating) {
DBG DbpString("Authentication failed!");
return false;
} else {
// Failed reading a block, could be (read/write) locked, skip block and re-authenticate
if (blocknr == 1) {
// Write the low part of the key in memory
memcpy(tag.sectors[1], key + 2, 4);
} else if (blocknr == 2) {
// Write the high part of the key in memory
tag.sectors[2][0] = 0x00;
tag.sectors[2][1] = 0x00;
tag.sectors[2][2] = key[0];
tag.sectors[2][3] = key[1];
} else {
// Just put zero's in the memory (of the unreadable block)
memset(tag.sectors[blocknr], 0x00, 4);
}
blocknr++;
bCrypto = false;
}
} else {
*txlen = 5;
memcpy(tx, "\xc0", nbytes(*txlen));
}
break;
}
// Received UID, crypto tag answer
case 32: {
// stage 1, got UID
if (bCrypto == false) {
DBG Dbprintf("hitag2_crypto: key array ");
DBG Dbhexdump(6, key, false);
uint64_t ui64key = key[0] | ((uint64_t)key[1]) << 8 | ((uint64_t)key[2]) << 16 | ((uint64_t)key[3]) << 24 | ((uint64_t)key[4]) << 32 | ((uint64_t)key[5]) << 40;
uint32_t ui32uid = rx[0] | ((uint32_t)rx[1]) << 8 | ((uint32_t)rx[2]) << 16 | ((uint32_t)rx[3]) << 24;
DBG Dbprintf("hitag2_crypto: key=0x%x%x uid=0x%x"
, (uint32_t)((REV64(ui64key)) >> 32)
, (uint32_t)((REV64(ui64key)) & 0xffffffff)
, REV32(ui32uid)
);
cipher_state = ht2_hitag2_init(REV64(ui64key), REV32(ui32uid), 0);
// PRN 00 00 00 00
memset(tx, 0x00, 4);
// Secret data FF FF FF FF
memset(tx + 4, 0xff, 4);
ht2_hitag2_cipher_transcrypt(&cipher_state, tx + 4, 4, 0);
*txlen = 64;
bCrypto = true;
bAuthenticating = true;
} else {
// stage 2, got config byte+password TAG, discard as will read later
if (bAuthenticating) {
bAuthenticating = false;
if (write) {
if (hitag2_write_page(rx, rxlen, tx, txlen) == false) {
return false;
}
break;
}
} else { // stage 2+, got data block
// Store the received block
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
}
if (blocknr > 7) {
DBG DbpString("Read successful!");
bSuccessful = true;
return false;
} else {
*txlen = 10;
tx[0] = HITAG2_READ_PAGE | (blocknr << 3) | ((blocknr ^ 7) >> 2);
tx[1] = ((blocknr ^ 7) << 6);
}
}
break;
}
default: {
DBG Dbprintf("Unknown frame length: " _RED_("%d"), rxlen);
return false;
}
}
}
// try to avoid double encryption calls
if (bCrypto && bAuthenticating == false) {
ht2_hitag2_cipher_transcrypt(&cipher_state, tx, *txlen / 8, *txlen % 8);
}
return true;
}
static bool hitag2_authenticate(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool write) {
// Reset the transmission frame length
*txlen = 0;
// Try to find out which command was send by selecting on length (in bits)
switch (rxlen) {
case 0: {
// No answer, try to resurrect
// Stop if there is no answer while we are in crypto mode (after sending NrAr)
if (bCrypto) {
DBG DbpString("No answer after sending NrAr!");
return false;
} else {
// Failed during authentication
if (bAuthenticating) {
DBG DbpString("Authentication - failed!");
return false;
}
DBG DbpString("Authenticating - send 0xC0");
*txlen = 5;
memcpy(tx, "\xC0", nbytes(*txlen));
}
break;
}
case 32: {
// Received UID or crypto tag answer
if (bCrypto == false) {
*txlen = 64;
memcpy(tx, NrAr, sizeof(NrAr));
bCrypto = true;
bAuthenticating = true;
DBG DbpString("Authenticating sending NrAr");
} else {
DBG DbpString("Authentication successful!");
// stage 2, got config byte+password TAG, discard as will read later
if (bAuthenticating) {
bAuthenticating = false;
if (write) {
if (hitag2_write_page(rx, rxlen, tx, txlen) == false) {
return false;
}
break;
}
} else { // stage 2+, got data block
// Store the received block
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
}
if (blocknr > 7) {
DBG DbpString("Read successful!");
bSuccessful = true;
return false;
} else {
DBG Dbprintf("Sending read block %u", blocknr);
*txlen = 10;
tx[0] = HITAG2_READ_PAGE | (blocknr << 3) | ((blocknr ^ 7) >> 2);
tx[1] = ((blocknr ^ 7) << 6);
}
}
break;
}
default: {
DBG Dbprintf("Unknown frame length: " _RED_("%d"), rxlen);
return false;
}
}
return true;
}
static bool hitag2_test_auth_attempts(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
// Reset the transmission frame length
*txlen = 0;
// Try to find out which command was send by selecting on length (in bits)
switch (rxlen) {
// No answer, try to resurrect
case 0: {
// Stop if there is no answer while we are in crypto mode (after sending NrAr)
if (bCrypto) {
Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x Failed, removed entry!", NrAr[0], NrAr[1], NrAr[2], NrAr[3], NrAr[4], NrAr[5], NrAr[6], NrAr[7]);
// Removing failed entry from authentications table
memcpy(auth_table + auth_table_pos, auth_table + auth_table_pos + 8, 8);
auth_table_len -= 8;
// Return if we reached the end of the authentications table
bCrypto = false;
if (auth_table_pos == auth_table_len) {
return false;
}
// Copy the next authentication attempt in row (at the same position, b/c we removed last failed entry)
memcpy(NrAr, auth_table + auth_table_pos, 8);
}
*txlen = 5;
memcpy(tx, "\xc0", nbytes(*txlen));
}
break;
// Received UID, crypto tag answer, or read block response
case 32: {
if (bCrypto == false) {
*txlen = 64;
memcpy(tx, NrAr, 8);
bCrypto = true;
} else {
Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x ( " _GREEN_("ok") " )", NrAr[0], NrAr[1], NrAr[2], NrAr[3], NrAr[4], NrAr[5], NrAr[6], NrAr[7]);
bCrypto = false;
if ((auth_table_pos + 8) == auth_table_len) {
return false;
}
auth_table_pos += 8;
memcpy(NrAr, auth_table + auth_table_pos, 8);
}
}
break;
default: {
Dbprintf("Unknown frame length: " _RED_("%d"), rxlen);
return false;
}
break;
}
return true;
}
// Hitag 2 Sniffing
void hitag_sniff(void) {
FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
BigBuf_free();
BigBuf_Clear_ext(false);
clear_trace();
set_tracing(true);
// Set up eavesdropping mode, frequency divisor which will drive the FPGA
// and analog mux selection.
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_TOGGLE_MODE);
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); // 125Khz
SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
RELAY_OFF();
}
// T0 18-22 fc (total time ZERO)
// T1 26-32 fc (total time ONE)
// Tstop 36 > fc (high field stop limit)
// Tlow 4-10 fc (reader field low time)
void SniffHitag2(bool ledcontrol) {
if (ledcontrol) LED_D_ON();
FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
BigBuf_free();
BigBuf_Clear_ext(false);
clear_trace();
set_tracing(true);
/*
lf_init(false, false, ledcontrol);
// no logging of the raw signal
g_logging = true;
uint32_t total_count = 0;
uint8_t rx[HITAG_FRAME_BIT_COUNT * 2];
while (BUTTON_PRESS() == false) {
lf_reset_counter();
WDT_HIT();
size_t periods = 0;
uint16_t rxlen = 0;
memset(rx, 0x00, sizeof(rx));
// Use the current modulation state as starting point
uint8_t mod_state = lf_get_reader_modulation();
while (rxlen < sizeof(rx)) {
periods = lf_count_edge_periods(64);
// Evaluate the number of periods before the next edge
if (periods >= 24 && periods < 64) {
// Detected two sequential equal bits and a modulation switch
// NRZ modulation: (11 => --|) or (11 __|)
rx[rxlen++] = mod_state;
if (rxlen < sizeof(rx)) {
rx[rxlen++] = mod_state;
}
// toggle tag modulation state
mod_state ^= 1;
} else if (periods > 0 && periods < 24) {
// Detected one bit and a modulation switch
// NRZ modulation: (1 => -|) or (0 _|)
rx[rxlen++] = mod_state;
mod_state ^= 1;
} else {
mod_state ^= 1;
// The function lf_count_edge_periods() returns > 64 periods, this is not a valid number periods
Dbprintf("Detected unexpected period count... " _YELLOW_("%zu"), periods);
break;
}
}
if (rxlen < 10) {
continue;
}
// tag sends 11111 + uid,
bool got_tag = (memcmp(rx, "\x01\x00\x01\x00\x01\x00\x01\x00\x01\x00", 10) == 0);
Dbprintf("periods... %zu rxlen... %u", periods, rxlen);
Dbhexdump(rxlen, rx, false);
if (got_tag) {
bool bad_man = false;
uint16_t bitnum = 0;
// mqnchester decode
for (uint16_t i = 0; i < rxlen; i += 2) {
if (rx[i] == 1 && (rx[i + 1] == 0)) {
rx[bitnum++] = 0;
} else if ((rx[i] == 0) && rx[i + 1] == 1) {
rx[bitnum++] = 1;
} else {
bad_man = true;
break;
}
}
// Dbprintf(_YELLOW_("TAG") " rxlen... %u bitnum... %u", rxlen, bitnum);
if (bad_man) {
Dbprintf("bad manchester ( bitnum %u )", bitnum);
continue;;
}
if (bitnum < 5) {
DbpString("too few bits");
continue;
}
// Pack the response into a byte array,
// and skip header 11111 (start at idx 5)
rxlen = 0;
for (uint16_t i = 5; i < bitnum; i++) {
uint8_t b = rx[i];
rx[rxlen >> 3] |= b << (7 - (rxlen % 8));
rxlen++;
}
// skip spurious bit
if (rxlen % 8 == 1) {
rxlen--;
}
// nothing to log
if (rxlen == 0) {
if (ledcontrol) LED_A_INV();
continue;
}
LogTraceBits(rx, rxlen, 0, periods, false);
total_count += nbytes(rxlen);
} else {
// nothing to log
if (rxlen < 3) {
if (ledcontrol) LED_A_INV();
continue;
}
uint16_t n = 0;
for (uint16_t i = 0; i < rxlen; i++) {
uint8_t b = rx[i];
rx[n >> 3] |= b << (7 - (n % 8));
n++;
}
// decode reader comms
LogTraceBits(rx, n, 0, periods, true);
total_count += nbytes(n);
}
if (ledcontrol) LED_A_INV();
}
lf_finalize(ledcontrol);
Dbprintf("Collected %u bytes", total_count);
switch_off();
BigBuf_free();
}
*/
// Set up eavesdropping mode, frequency divisor which will drive the FPGA
// and analog mux selection.
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_TOGGLE_MODE);
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); // 125Khz
SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
RELAY_OFF();
// Configure output pin that is connected to the FPGA (for modulating)
// AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
// AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
// Disable modulation, we are going to eavesdrop, not modulate ;)
// LOW(GPIO_SSC_DOUT);
// Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
// Disable timer during configuration
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
// Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
// external trigger rising edge, load RA on rising edge of TIOA.
AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_BOTH | AT91C_TC_ABETRG | AT91C_TC_LDRA_BOTH;
// Enable and reset counter
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
// Assert a sync signal. This sets all timers to 0 on next active clock edge
AT91C_BASE_TCB->TCB_BCR = 1;
int frame_count = 0, response = 0, lastbit = 1, tag_sof = 4;
int overflow = 0;
bool rising_edge, reader_frame = false, bSkip = true;
// bool exit_due_to_overflow;
// HACK -- add one byte to avoid rewriting manchester decoder for edge case
uint8_t rx[HITAG_FRAME_LEN + 1];
size_t rxlen = 0;
auth_table_len = 0;
auth_table_pos = 0;
auth_table = (uint8_t *)BigBuf_calloc(AUTH_TABLE_LENGTH);
while (BUTTON_PRESS() == false) {
WDT_HIT();
// bool exit_due_to_overflow = false;
// Receive frame, watch for at most T0 * EOF periods
while (AT91C_BASE_TC1->TC_CV < (HITAG_T0 * HITAG_T_EOF)) {
// Check if rising edge in modulation is detected
if (AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
// Retrieve the new timing values
int ra = (AT91C_BASE_TC1->TC_RA / HITAG_T0) + overflow;
overflow = 0;
// Find out if we are dealing with a rising or falling edge
rising_edge = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME) > 0;
// Shorter periods will only happen with reader frames
if (reader_frame == false && rising_edge && ra < HITAG_T_TAG_CAPTURE_ONE_HALF) {
// Switch from tag to reader capture
if (ledcontrol) LED_C_OFF();
reader_frame = true;
rxlen = 0;
}
// Only handle if reader frame and rising edge, or tag frame and falling edge
if (reader_frame != rising_edge) {
overflow += ra;
continue;
}
// Add the buffered timing values of earlier captured edges which were skipped
ra += overflow;
overflow = 0;
if (reader_frame) {
if (ledcontrol) LED_B_ON();
// Capture reader frame
if (ra >= HITAG_T_STOP) {
// if (rxlen != 0) {
//DbpString("wierd0?");
// }
// Capture the T0 periods that have passed since last communication or field drop (reset)
response = (ra - HITAG_T_LOW);
if (rxlen != 0) { Dbprintf("ra - HITAG_T_LOW... %i", response); }
} else if (ra >= HITAG_T_1_MIN) {
// '1' bit
rx[rxlen / 8] |= 1 << (7 - (rxlen % 8));
rxlen++;
} else if (ra >= HITAG_T_0_MIN) {
// '0' bit
rx[rxlen / 8] |= 0 << (7 - (rxlen % 8));
rxlen++;
}
} else {
if (ledcontrol) LED_C_ON();
// Capture tag frame (manchester decoding using only falling edges)
if (ra >= HITAG_T_EOF) {
// if (rxlen != 0) {
//DbpString("wierd1?");
// }
// Capture the T0 periods that have passed since last communication or field drop (reset)
// We always receive a 'one' first, which has the falling edge after a half period |-_|
response = ra - HITAG_T_TAG_HALF_PERIOD;
} else if (ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
// Manchester coding example |-_|_-|-_| (101)
rx[rxlen / 8] |= 0 << (7 - (rxlen % 8));
rxlen++;
rx[rxlen / 8] |= 1 << (7 - (rxlen % 8));
rxlen++;
} else if (ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
// Manchester coding example |_-|...|_-|-_| (0...01)
rx[rxlen / 8] |= 0 << (7 - (rxlen % 8));
rxlen++;
// We have to skip this half period at start and add the 'one' the second time
if (bSkip == false) {
rx[rxlen / 8] |= 1 << (7 - (rxlen % 8));
rxlen++;
}
lastbit = !lastbit;
bSkip = !bSkip;
} else if (ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
// Manchester coding example |_-|_-| (00) or |-_|-_| (11)
if (tag_sof) {
// Ignore bits that are transmitted during SOF
tag_sof--;
} else {
// bit is same as last bit
rx[rxlen / 8] |= lastbit << (7 - (rxlen % 8));
rxlen++;
}
}
}
}
} // end while
// Check if frame was captured
if (rxlen) {
frame_count++;
LogTraceBits(rx, rxlen, response, 0, reader_frame);
// Check if we recognize a valid authentication attempt
if (rxlen == 64) {
// Store the authentication attempt
if (auth_table_len < (AUTH_TABLE_LENGTH - 8)) {
memcpy(auth_table + auth_table_len, rx, 8);
auth_table_len += 8;
}
}
if (ledcontrol) {
LED_B_OFF();
LED_C_OFF();
}
response = 0;
reader_frame = false;
lastbit = 1;
bSkip = true;
tag_sof = 4;
overflow = 0;
if (ledcontrol) {
LED_B_OFF();
LED_C_OFF();
}
} else {
// Save the timer overflow, will be 0 when frame was received
overflow += (AT91C_BASE_TC1->TC_CV / HITAG_T0);
}
// Reset the frame length
rxlen = 0;
// Reset the timer to restart while-loop that receives frames
AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
// Assert a sync signal. This sets all timers to 0 on next active clock edge
AT91C_BASE_TCB->TCB_BCR = 1;
}
if (ledcontrol) LEDsoff();
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
DBG Dbprintf("frames.......... %d", frame_count);
Dbprintf("Auth attempts... %d", (auth_table_len / 8));
switch_off();
BigBuf_free();
}
// Hitag 2 simulation
void SimulateHitag2(bool ledcontrol) {
BigBuf_free();
BigBuf_Clear_ext(false);
clear_trace();
set_tracing(true);
// empties bigbuff etc
lf_init(false, true, ledcontrol);
int response = 0;
uint8_t rx[HITAG_FRAME_LEN] = {0};
uint8_t tx[HITAG_FRAME_LEN] = {0};
auth_table_len = 0;
auth_table_pos = 0;
// auth_table = BigBuf_calloc(AUTH_TABLE_LENGTH);
DbpString("Starting Hitag 2 simulation");
// hitag2 state machine?
hitag2_init();
// printing
uint32_t block = 0;
for (size_t i = 0; i < 12; i++) {
// num2bytes?
for (size_t j = 0; j < 4; j++) {
block <<= 8;
block |= tag.sectors[i][j];
}
Dbprintf("| %d | %08x |", i, block);
}
size_t max_nrzs = 8 * HITAG_FRAME_LEN + 5;
uint8_t nrz_samples[max_nrzs];
// uint32_t command_start = 0, command_duration = 0;
// int16_t checked = 0;
// SIMULATE
uint32_t signal_size = 10000;
while (BUTTON_PRESS() == false) {
// use malloc
initSampleBufferEx(&signal_size, true);
if (ledcontrol) {
LED_D_ON();
LED_A_OFF();
}
// lf_reset_counter();
WDT_HIT();
/*
// only every 1000th times, in order to save time when collecting samples.
if (checked == 100) {
if (data_available()) {
checked = -1;
break;
} else {
checked = 0;
}
}
++checked;
*/
size_t rxlen = 0, txlen = 0;
// Keep administration of the first edge detection
bool waiting_for_first_edge = true;
// Did we detected any modulaiton at all
bool detected_modulation = false;
// Use the current modulation state as starting point
uint8_t reader_modulation = lf_get_reader_modulation();
// Receive frame, watch for at most max_nrzs periods
// Reset the number of NRZ samples and use edge detection to detect them
size_t nrzs = 0;
while (nrzs < max_nrzs) {
// Get the timing of the next edge in number of wave periods
size_t periods = lf_count_edge_periods(128);
// Just break out of loop after an initial time-out (tag is probably not available)
// The function lf_count_edge_periods() returns 0 when a time-out occurs
if (periods == 0) {
break;
}
if (ledcontrol) LED_A_ON();
// Are we dealing with the first incoming edge
if (waiting_for_first_edge) {
// Register the number of periods that have passed
response = periods;
// Indicate that we have dealt with the first edge
waiting_for_first_edge = false;
// The first edge is always a single NRZ bit, force periods on 16
periods = 16;
// We have received more than 0 periods, so we have detected a tag response
detected_modulation = true;
}
// Evaluate the number of periods before the next edge
if (periods > 24 && periods <= 64) {
// Detected two sequential equal bits and a modulation switch
// NRZ modulation: (11 => --|) or (11 __|)
nrz_samples[nrzs++] = reader_modulation;
if (nrzs < max_nrzs) {
nrz_samples[nrzs++] = reader_modulation;
}
// Invert tag modulation state
reader_modulation ^= 1;
} else if (periods > 0 && periods <= 24) {
// Detected one bit and a modulation switch
// NRZ modulation: (1 => -|) or (0 _|)
nrz_samples[nrzs++] = reader_modulation;
reader_modulation ^= 1;
} else {
reader_modulation ^= 1;
// The function lf_count_edge_periods() returns > 64 periods, this is not a valid number periods
Dbprintf("Detected unexpected period count: %zu", periods);
break;
}
}
if (ledcontrol) LED_D_OFF();
// If there is no response, just repeat the loop
if (!detected_modulation) continue;
if (ledcontrol) LED_A_OFF();
// Make sure we always have an even number of samples. This fixes the problem
// of ending the manchester decoding with a zero. See the example below where
// the '|' character is end of modulation
// One at the end: ..._-|_____...
// Zero at the end: ...-_|_____...
// The last modulation change of a zero is not detected, but we should take
// the half period in account, otherwise the demodulator will fail.
if ((nrzs % 2) != 0) {
if (nrzs >= max_nrzs) {
Dbprintf("max_nrzs (%d) is odd? Must be even!", max_nrzs); // should be a static assert above
continue;
}
nrz_samples[nrzs++] = reader_modulation;
}
if (ledcontrol) LED_B_ON();
// decode bitstream
manrawdecode((uint8_t *)nrz_samples, &nrzs, true, 0);
// Verify if the header consists of five consecutive ones
if (nrzs < 5) {
Dbprintf("Detected unexpected number of manchester decoded samples [%d]", nrzs);
continue;
} else {
for (size_t i = 0; i < 5; i++) {
if (nrz_samples[i] != 1) {
Dbprintf("Detected incorrect header, the bit [%d] is zero instead of one", i);
}
}
}
// Pack the response into a byte array
for (size_t i = 5; i < 37; i++) {
uint8_t bit = nrz_samples[i];
rx[rxlen / 8] |= bit << (7 - (rxlen % 8));
rxlen++;
}
// Check if frame was captured
if (rxlen > 4) {
LogTraceBits(rx, rxlen, response, response, true);
// Process the incoming frame (rx) and prepare the outgoing frame (tx)
hitag2_handle_reader_command(rx, rxlen, tx, &txlen);
// Wait for HITAG_T_WAIT_1 carrier periods after the last reader bit,
// not that since the clock counts since the rising edge, but T_Wait1 is
// with respect to the falling edge, we need to wait actually (T_Wait1 - T_Low)
// periods. The gap time T_Low varies (4..10). All timer values are in
// terms of T0 units (HITAG_T_WAIT_1_MIN - HITAG_T_LOW )
lf_wait_periods(HITAG_T_WAIT_1_MIN);
// Send and store the tag answer (if there is any)
if (txlen) {
// Transmit the tag frame
//hitag_send_frame(tx, txlen);
lf_manchester_send_bytes(tx, txlen, ledcontrol);
// Store the frame in the trace
LogTraceBits(tx, txlen, 0, 0, false);
}
// Reset the received frame and response timing info
memset(rx, 0x00, sizeof(rx));
response = 0;
if (ledcontrol) LED_B_OFF();
}
}
lf_finalize(ledcontrol);
// release allocated memory from BigBuff.
BigBuf_free();
DbpString("Sim stopped");
// reply_ng(CMD_LF_HITAG_SIMULATE, (checked == -1) ? PM3_EOPABORTED : PM3_SUCCESS, (uint8_t *)tag.sectors, tag_size);
}
void ReaderHitag(const lf_hitag_data_t *payload, bool ledcontrol) {
uint32_t command_start = 0, command_duration = 0;
uint32_t response_start = 0, response_duration = 0;
uint8_t rx[HITAG_FRAME_LEN] = {0};
size_t rxlen = 0;
uint8_t txbuf[HITAG_FRAME_LEN] = {0};
uint8_t *tx = txbuf;
size_t txlen = 0;
int t_wait_1 = 204;
int t_wait_1_guard = 8;
int t_wait_2 = 128;
size_t tag_size = 48;
bool bStop = false;
// Raw demodulation/decoding by sampling edge periods
size_t periods = 0;
// Reset the return status
bSuccessful = false;
bCrypto = false;
// Clean up trace and prepare it for storing frames
set_tracing(true);
clear_trace();
// Check configuration
switch (payload->cmd) {
case HT1F_PLAIN: {
DBG Dbprintf("Read public blocks in plain mode");
// this part will be unreadable
memset(tag.sectors + 2, 0x0, 30);
blocknr = 0;
break;
}
case HT1F_AUTHENTICATE: {
DBG Dbprintf("Read all blocks in authed mode");
memcpy(nonce, payload->nonce, 4);
memcpy(key, payload->key, 4);
memcpy(logdata_0, payload->logdata_0, 4);
memcpy(logdata_1, payload->logdata_1, 4);
// TEST
memset(nonce, 0x0, 4);
memset(logdata_1, 0x00, 4);
byte_value = 0;
key_no = payload->key_no;
DBG Dbprintf("Authenticating using key #%u :", key_no);
DBG Dbhexdump(4, key, false);
DBG DbpString("Nonce:");
DBG Dbhexdump(4, nonce, false);
DBG DbpString("Logdata_0:");
DBG Dbhexdump(4, logdata_0, false);
DBG DbpString("Logdata_1:");
DBG Dbhexdump(4, logdata_1, false);
blocknr = 0;
break;
}
case HT2F_PASSWORD: {
DBG Dbprintf("List identifier in password mode");
if (memcmp(payload->pwd, "\x00\x00\x00\x00", 4) == 0) {
memcpy(password, tag.sectors[1], sizeof(password));
} else {
memcpy(password, payload->pwd, sizeof(password));
}
blocknr = 0;
bPwd = false;
bAuthenticating = false;
break;
}
case HT2F_AUTHENTICATE: {
DBG DbpString("Authenticating using NrAr pair:");
memcpy(NrAr, payload->NrAr, 8);
DBG Dbhexdump(8, NrAr, false);
// We can't read block 0, 1, 2..
blocknr = 3;
bCrypto = false;
bPwd = false;
bAuthenticating = false;
break;
}
case HT2F_CRYPTO: {
DBG DbpString("Authenticating using key:");
memcpy(key, payload->key, 6); //HACK; 4 or 6?? I read both in the code.
DBG Dbhexdump(6, key, false);
DBG DbpString("Nonce:");
DBG Dbhexdump(4, nonce, false);
memcpy(nonce, payload->data, 4);
blocknr = 0;
bCrypto = false;
bAuthenticating = false;
break;
}
case HT2F_TEST_AUTH_ATTEMPTS: {
DBG Dbprintf("Testing " _YELLOW_("%d") " authentication attempts", (auth_table_len / 8));
auth_table_pos = 0;
memcpy(NrAr, auth_table, 8);
bCrypto = false;
break;
}
default: {
DBG Dbprintf("Error, unknown function: " _RED_("%d"), payload->cmd);
set_tracing(false);
reply_ng(CMD_LF_HITAG_READER, PM3_ESOFT, NULL, 0);
return;
}
}
if (ledcontrol) LED_D_ON();
// hitag 2 state machine?
hitag2_init();
// Tag specific configuration settings (sof, timings, etc.)
// TODO HTS
/* if (payload->cmd <= HTS_LAST_CMD) {
// hitag S settings
t_wait_1 = 204;
t_wait_2 = 128;
flipped_bit = 0;
tag_size = 8;
DBG DbpString("Configured for " _YELLOW_("Hitag S") " reader");
} else */
if (payload->cmd <= HT1_LAST_CMD) {
// hitag 1 settings
t_wait_1 = 204;
t_wait_2 = 128;
tag_size = 256;
flipped_bit = 0;
DBG DbpString("Configured for " _YELLOW_("Hitag 1") " reader");
} else if (payload->cmd <= HT2_LAST_CMD) {
// hitag 2 settings
t_wait_1 = HITAG_T_WAIT_1_MIN;
t_wait_2 = HITAG_T_WAIT_2_MIN;
tag_size = 48;
DBG DbpString("Configured for " _YELLOW_("Hitag 2") " reader");
}
// init as reader
lf_init(true, false, ledcontrol);
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
uint8_t tag_modulation;
size_t max_nrzs = (8 * HITAG_FRAME_LEN + 5) * 2; // up to 2 nrzs per bit
uint8_t nrz_samples[max_nrzs];
bool turn_on = true;
size_t nrzs = 0;
int16_t checked = 0;
uint32_t signal_size = 10000;
while (bStop == false && BUTTON_PRESS() == false) {
// use malloc
initSampleBufferEx(&signal_size, true);
WDT_HIT();
// only every 1000th times, in order to save time when collecting samples.
if (checked == 4000) {
if (data_available()) {
checked = -1;
break;
} else {
checked = 0;
}
}
++checked;
// By default reset the transmission buffer
tx = txbuf;
switch (payload->cmd) {
case HT1F_PLAIN: {
bStop = !hitag1_plain(rx, rxlen, tx, &txlen, false);
break;
}
case HT1F_AUTHENTICATE: {
bStop = !hitag1_authenticate(rx, rxlen, tx, &txlen);
break;
}
case HT2F_PASSWORD: {
bStop = !hitag2_password(rx, rxlen, tx, &txlen, false);
break;
}
case HT2F_AUTHENTICATE: {
bStop = !hitag2_authenticate(rx, rxlen, tx, &txlen, false);
break;
}
case HT2F_CRYPTO: {
bStop = !hitag2_crypto(rx, rxlen, tx, &txlen, false);
break;
}
case HT2F_TEST_AUTH_ATTEMPTS: {
bStop = !hitag2_test_auth_attempts(rx, rxlen, tx, &txlen);
break;
}
default: {
DBG Dbprintf("Error, unknown function: " _RED_("%d"), payload->cmd);
goto out;
}
}
if (bStop) {
break;
}
if (turn_on) {
// Wait 50ms with field off to be sure the transponder gets reset
SpinDelay(50);
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
turn_on = false;
// Wait with field on to be in "Wait for START_AUTH" timeframe
lf_wait_periods(HITAG_T_WAIT_POWERUP + HITAG_T_WAIT_START_AUTH_MAX / 4);
command_start += HITAG_T_WAIT_POWERUP + HITAG_T_WAIT_START_AUTH_MAX / 4;
} else {
// Wait for t_wait_2 carrier periods after the last tag bit before transmitting,
lf_wait_periods(t_wait_2);
command_start += t_wait_2;
}
// Transmit the reader frame
command_duration = hitag_reader_send_frame(tx, txlen);
response_start = command_start + command_duration;
// Let the antenna and ADC values settle
// And find the position where edge sampling should start
lf_wait_periods(t_wait_1 - t_wait_1_guard);
response_start += t_wait_1 - t_wait_1_guard;
// Keep administration of the first edge detection
bool waiting_for_first_edge = true;
// Did we detected any modulaiton at all
bool detected_tag_modulation = false;
// Use the current modulation state as starting point
tag_modulation = lf_get_tag_modulation();
// Reset the number of NRZ samples and use edge detection to detect them
nrzs = 0;
while (nrzs < max_nrzs) {
// Get the timing of the next edge in number of wave periods
periods = lf_count_edge_periods(128);
// Are we dealing with the first incoming edge
if (waiting_for_first_edge) {
// Just break out of loop after an initial time-out (tag is probably not available)
if (periods == 0) {
break;
}
if (tag_modulation == 0) {
// hitag replies always start with 11111 == 1010101010, if we see 0
// it means we missed the first period, e.g. if the signal never crossed 0 since reader signal
// so let's add it:
nrz_samples[nrzs++] = tag_modulation ^ 1;
// Register the number of periods that have passed
// we missed the begin of response but we know it happened one period of 16 earlier
response_start += periods - 16;
response_duration = response_start;
} else {
// Register the number of periods that have passed
response_start += periods;
response_duration = response_start;
}
// Indicate that we have dealt with the first edge
waiting_for_first_edge = false;
// The first edge is always a single NRZ bit, force periods on 16
periods = 16;
// We have received more than 0 periods, so we have detected a tag response
detected_tag_modulation = true;
} else {
// The function lf_count_edge_periods() returns 0 when a time-out occurs
if (periods == 0) {
DBG Dbprintf("Detected timeout after [" _YELLOW_("%zu") "] nrz samples", nrzs);
break;
}
}
// Evaluate the number of periods before the next edge
if (periods > 24 && periods <= 64) {
// Detected two sequential equal bits and a modulation switch
// NRZ modulation: (11 => --|) or (11 __|)
nrz_samples[nrzs++] = tag_modulation;
if (nrzs < max_nrzs) {
nrz_samples[nrzs++] = tag_modulation;
}
response_duration += periods;
// Invert tag modulation state
tag_modulation ^= 1;
} else if (periods > 0 && periods <= 24) {
// Detected one bit and a modulation switch
// NRZ modulation: (1 => -|) or (0 _|)
nrz_samples[nrzs++] = tag_modulation;
response_duration += periods;
tag_modulation ^= 1;
} else {
// The function lf_count_edge_periods() returns > 64 periods, this is not a valid number periods
DBG Dbprintf("Detected unexpected period count: " _RED_("%zu"), periods);
break;
}
}
// Store the TX frame, we do this now at this point, to avoid delay in processing
// and to be able to overwrite the first samples with the trace (since they currently
// still use the same memory space)
LogTraceBits(tx, txlen, command_start, command_start + command_duration, true);
// Reset values for receiving frames
memset(rx, 0x00, sizeof(rx));
rxlen = 0;
// If there is no response
if (detected_tag_modulation == false) {
checked = -1;
goto out;
}
// Make sure we always have an even number of samples. This fixes the problem
// of ending the manchester decoding with a zero. See the example below where
// the '|' character is end of modulation
// One at the end: ..._-|_____...
// Zero at the end: ...-_|_____...
// The last modulation change of a zero is not detected, but we should take
// the half period in account, otherwise the demodulator will fail.
if ((nrzs % 2) != 0) {
if (nrzs >= max_nrzs) {
DBG Dbprintf("max_nrzs ( " _YELLOW_("%zu") " ) is odd? Must be even!", max_nrzs);
continue;
}
nrz_samples[nrzs++] = tag_modulation;
}
if (ledcontrol) LED_B_ON();
// decode bitstream
manrawdecode((uint8_t *)nrz_samples, &nrzs, true, 0);
// decode frame
// Verify if the header consists of five consecutive ones
if (nrzs < 5) {
DBG Dbprintf("Detected unexpected number of manchester decoded samples [%zu]", nrzs);
break;
} else {
size_t i;
for (i = 0; i < 5; i++) {
if (nrz_samples[i] != 1) {
DBG Dbprintf("Detected incorrect header, the bit [%zu] is zero instead of one, abort", i);
break;
}
}
if (i < 5) {
break;
}
}
// Pack the response into a byte array
for (size_t i = 5; i < nrzs && rxlen < (sizeof(rx) << 3); i++) {
uint8_t bit = nrz_samples[i];
if (bit > 1) { // When Manchester detects impossible symbol it writes "7"
DBG Dbprintf("Error in Manchester decoding, abort");
break;
}
rx[rxlen >> 3] |= bit << (7 - (rxlen % 8));
rxlen++;
}
// skip spurious bit
if (rxlen % 8 == 1) {
rxlen--;
}
// Check if frame was captured and store it
LogTraceBits(rx, rxlen, response_start, response_start + response_duration, false);
// TODO when using cumulative time for command_start, pm3 doesn't reply anymore, e.g. on lf hitag reader --23 -k 4F4E4D494B52
// Use delta time?
// command_start = response_start + response_duration;
command_start = 0;
nrzs = 0;
}
out:
lf_finalize(ledcontrol);
// release allocated memory from BigBuff.
BigBuf_free();
if (checked == -1) {
reply_ng(CMD_LF_HITAG_READER, PM3_ESOFT, NULL, 0);
}
reply_ng(CMD_LF_HITAG_READER
, (bSuccessful) ? PM3_SUCCESS : PM3_EFAILED
, (uint8_t *)tag.sectors
, tag_size
);
}
void WriterHitag(const lf_hitag_data_t *payload, bool ledcontrol) {
uint32_t command_start = 0;
uint32_t command_duration = 0;
uint32_t response_start = 0;
uint32_t response_duration = 0;
uint8_t rx[HITAG_FRAME_LEN];
size_t rxlen = 0;
uint8_t txbuf[HITAG_FRAME_LEN];
uint8_t *tx = txbuf;
size_t txlen = 0;
int t_wait_1 = 204;
int t_wait_1_guard = 8;
int t_wait_2 = 128;
size_t tag_size = 48;
bool bStop = false;
// Raw demodulation/decoding by sampling edge periods
size_t periods = 0;
// iceman: Hitag2 is filled with static global vars.
// these following are globals status indicator :-|
// Reset the return status
bSuccessful = false;
writestate = WRITE_STATE_START;
blocknr = 0;
// Clean up trace and prepare it for storing frames
set_tracing(true);
clear_trace();
// Check configuration
switch (payload->cmd) {
case HT2F_CRYPTO: {
DBG DbpString("Authenticating using key:");
memcpy(key, payload->key, 6); //HACK; 4 or 6?? I read both in the code.
memcpy(writedata, payload->data, 4);
Dbhexdump(6, key, false);
blocknr = payload->page;
bCrypto = false;
bAuthenticating = false;
}
break;
case HT2F_PASSWORD: {
DBG DbpString("Authenticating using password:");
if (memcmp(payload->pwd, "\x00\x00\x00\x00", 4) == 0) {
memcpy(password, tag.sectors[1], sizeof(password));
} else {
memcpy(password, payload->pwd, sizeof(password));
}
memcpy(writedata, payload->data, 4);
DBG Dbhexdump(4, password, false);
blocknr = payload->page;
bPwd = false;
bAuthenticating = false;
}
break;
default: {
DBG Dbprintf("Error, unknown function: " _RED_("%d"), payload->cmd);
reply_ng(CMD_LF_HITAG2_WRITE, PM3_ESOFT, NULL, 0);
return;
}
break;
}
if (ledcontrol) LED_D_ON();
hitag2_init();
// init as reader
lf_init(true, false, ledcontrol);
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
// Tag specific configuration settings (sof, timings, etc.)
// TODO HTS
/* if (payload->cmd <= HTS_LAST_CMD) {
// hitag S settings
t_wait_1 = 204;
t_wait_2 = 128;
//tag_size = 256;
flipped_bit = 0;
tag_size = 8;
DBG DbpString("Configured for " _YELLOW_("Hitag S") " writer");
} else
*/
if (payload->cmd <= HT1_LAST_CMD) {
// hitag 1 settings
t_wait_1 = 204;
t_wait_2 = 128;
tag_size = 256;
flipped_bit = 0;
DBG DbpString("Configured for " _YELLOW_("Hitag 1") " writer");
} else if (payload->cmd <= HT2_LAST_CMD) {
// hitag 2 settings
t_wait_1 = HITAG_T_WAIT_1_MIN;
t_wait_2 = HITAG_T_WAIT_2_MIN;
tag_size = 48;
DBG DbpString("Configured for " _YELLOW_("Hitag 2") " writer");
}
uint8_t tag_modulation;
size_t max_nrzs = (8 * HITAG_FRAME_LEN + 5) * 2; // up to 2 nrzs per bit
uint8_t nrz_samples[max_nrzs];
size_t nrzs = 0;
int16_t checked = 0;
uint32_t signal_size = 10000;
bool turn_on = true;
while (bStop == false && BUTTON_PRESS() == false) {
// use malloc
initSampleBufferEx(&signal_size, true);
// only every 4000th times, in order to save time when collecting samples.
if (checked == 4000) {
if (data_available()) {
checked = -1;
break;
} else {
checked = 0;
}
}
++checked;
WDT_HIT();
// By default reset the transmission buffer
tx = txbuf;
switch (payload->cmd) {
case HT2F_CRYPTO: {
bStop = !hitag2_crypto(rx, rxlen, tx, &txlen, true);
break;
}
case HT2F_PASSWORD: {
bStop = !hitag2_password(rx, rxlen, tx, &txlen, true);
break;
}
default: {
goto out;
}
}
if (bStop) {
break;
}
if (turn_on) {
// Wait 50ms with field off to be sure the transponder gets reset
SpinDelay(50);
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
turn_on = false;
// Wait with field on to be in "Wait for START_AUTH" timeframe
lf_wait_periods(HITAG_T_WAIT_POWERUP + HITAG_T_WAIT_START_AUTH_MAX / 4);
command_start += HITAG_T_WAIT_POWERUP + HITAG_T_WAIT_START_AUTH_MAX / 4;
} else {
// Wait for t_wait_2 carrier periods after the last tag bit before transmitting,
lf_wait_periods(t_wait_2);
command_start += t_wait_2;
}
// Transmit the reader frame
command_duration = hitag_reader_send_frame(tx, txlen);
// global write state variable used
// tearoff occurred
if ((writestate == WRITE_STATE_PROG) && (tearoff_hook() == PM3_ETEAROFF)) {
reply_ng(CMD_LF_HITAG2_WRITE, PM3_ETEAROFF, NULL, 0);
lf_finalize(ledcontrol);
BigBuf_free();
return;
}
response_start = command_start + command_duration;
// Let the antenna and ADC values settle
// And find the position where edge sampling should start
lf_wait_periods(t_wait_1 - t_wait_1_guard);
response_start += t_wait_1 - t_wait_1_guard;
// Keep administration of the first edge detection
bool waiting_for_first_edge = true;
// Did we detected any modulaiton at all
bool detected_tag_modulation = false;
// Use the current modulation state as starting point
tag_modulation = lf_get_tag_modulation();
// Reset the number of NRZ samples and use edge detection to detect them
nrzs = 0;
while (nrzs < max_nrzs) {
// Get the timing of the next edge in number of wave periods
periods = lf_count_edge_periods(128);
// Are we dealing with the first incoming edge
if (waiting_for_first_edge) {
// Just break out of loop after an initial time-out (tag is probably not available)
if (periods == 0) {
break;
}
if (tag_modulation == 0) {
// hitag replies always start with 11111 == 1010101010, if we see 0
// it means we missed the first period, e.g. if the signal never crossed 0 since reader signal
// so let's add it:
nrz_samples[nrzs++] = tag_modulation ^ 1;
// Register the number of periods that have passed
// we missed the begin of response but we know it happened one period of 16 earlier
response_start += periods - 16;
response_duration = response_start;
} else {
// Register the number of periods that have passed
response_start += periods;
response_duration = response_start;
}
// Indicate that we have dealt with the first edge
waiting_for_first_edge = false;
// The first edge is always a single NRZ bit, force periods on 16
periods = 16;
// We have received more than 0 periods, so we have detected a tag response
detected_tag_modulation = true;
} else {
// The function lf_count_edge_periods() returns 0 when a time-out occurs
if (periods == 0) {
DBG Dbprintf("Detected timeout after [" _YELLOW_("%zu") "] nrz samples", nrzs);
break;
}
}
// Evaluate the number of periods before the next edge
if (periods > 24 && periods <= 64) {
// Detected two sequential equal bits and a modulation switch
// NRZ modulation: (11 => --|) or (11 __|)
nrz_samples[nrzs++] = tag_modulation;
if (nrzs < max_nrzs) {
nrz_samples[nrzs++] = tag_modulation;
}
response_duration += periods;
// Invert tag modulation state
tag_modulation ^= 1;
} else if (periods > 0 && periods <= 24) {
// Detected one bit and a modulation switch
// NRZ modulation: (1 => -|) or (0 _|)
nrz_samples[nrzs++] = tag_modulation;
response_duration += periods;
tag_modulation ^= 1;
} else {
// The function lf_count_edge_periods() returns > 64 periods, this is not a valid number periods
DBG Dbprintf("Detected unexpected period count: " _RED_("%zu"), periods);
break;
}
}
// Wait some extra time for flash to be programmed
// Store the TX frame, we do this now at this point, to avoid delay in processing
// and to be able to overwrite the first samples with the trace (since they currently
// still use the same memory space)
LogTraceBits(tx, txlen, command_start, command_start + command_duration, true);
// Reset values for receiving frames
memset(rx, 0x00, sizeof(rx));
rxlen = 0;
// If there is no response, just repeat the loop
if (detected_tag_modulation == false) {
continue;
}
// Make sure we always have an even number of samples. This fixes the problem
// of ending the manchester decoding with a zero. See the example below where
// the '|' character is end of modulation
// One at the end: ..._-|_____...
// Zero at the end: ...-_|_____...
// The last modulation change of a zero is not detected, but we should take
// the half period in account, otherwise the demodulator will fail.
if ((nrzs % 2) != 0) {
if (nrzs >= max_nrzs) {
Dbprintf("max_nrzs ( " _YELLOW_("%zu") " ) is odd? Must be even!", max_nrzs);
continue;
} else {
nrz_samples[nrzs++] = tag_modulation;
}
}
if (ledcontrol) LED_B_ON();
// decode bitstream
manrawdecode((uint8_t *)nrz_samples, &nrzs, true, 0);
// decode frame
// Verify if the header consists of five consecutive ones
if (nrzs < 5) {
DBG Dbprintf("Detected unexpected number of manchester decoded samples [%zu]", nrzs);
break;
} else {
size_t i;
for (i = 0; i < 5; i++) {
if (nrz_samples[i] != 1) {
DBG Dbprintf("Detected incorrect header, the bit " _YELLOW_("%zu") " is zero instead of one, abort", i);
break;
}
}
if (i < 5) {
break;
}
}
// Pack the response into a byte array
for (size_t i = 5; i < nrzs && rxlen < (sizeof(rx) << 3); i++) {
uint8_t bit = nrz_samples[i];
// When Manchester detects impossible symbol it writes "7"
if (bit > 1) {
DBG Dbprintf("Error in Manchester decoding, abort");
break;
}
// >> 3 instead of div by 8
rx[rxlen >> 3] |= bit << (7 - (rxlen % 8));
rxlen++;
}
// skip spurious bit
if (rxlen % 8 == 1) {
rxlen--;
}
// Check if frame was captured and store it
LogTraceBits(rx, rxlen, response_start, response_start + response_duration, false);
command_start = 0;
nrzs = 0;
}
out:
lf_finalize(ledcontrol);
// release allocated memory from BigBuff.
BigBuf_free();
if (checked == -1) {
reply_ng(CMD_LF_HITAG2_WRITE, PM3_ESOFT, NULL, 0);
}
reply_ng(CMD_LF_HITAG2_WRITE
, (bSuccessful) ? PM3_SUCCESS : PM3_EFAILED
, (uint8_t *)tag.sectors
, tag_size
);
}
static void ht2_send(bool turn_on, uint32_t *cmd_start
, uint32_t *cmd_duration, uint32_t *resp_start
, uint8_t *tx, size_t txlen, bool send_bits) {
// Tag specific configuration settings (sof, timings, etc.) HITAG2 Settings
#define T_WAIT_1_GUARD 7
if (turn_on) {
// Wait 50ms with field off to be sure the transponder gets reset
SpinDelay(50);
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
// Wait with field on to be in "Wait for START_AUTH" timeframe
lf_wait_periods(HITAG_T_WAIT_POWERUP + HITAG_T_WAIT_START_AUTH_MAX / 4);
*cmd_start += HITAG_T_WAIT_POWERUP + HITAG_T_WAIT_START_AUTH_MAX / 4;
} else {
// Wait for t_wait_2 carrier periods after the last tag bit before transmitting,
lf_wait_periods(HITAG_T_WAIT_2_MIN + HITAG_T_WAIT_2_MIN);
*cmd_start += (HITAG_T_WAIT_2_MIN + HITAG_T_WAIT_2_MIN);
}
// Transmit the reader frame
if (send_bits) {
*cmd_duration = hitag_reader_send_framebits(tx, txlen);
} else {
*cmd_duration = hitag_reader_send_frame(tx, txlen);
}
*resp_start = (*cmd_start + *cmd_duration);
*resp_start += (HITAG_T_WAIT_1_MIN - T_WAIT_1_GUARD);
// Let the antenna and ADC values settle
// And find the position where edge sampling should start
lf_wait_periods(HITAG_T_WAIT_1_MIN - T_WAIT_1_GUARD);
}
static bool ht2_receive(uint32_t *resp_start, uint32_t *resp_duration, uint8_t *nrz_samples, size_t *samples) {
// Keep administration of the first edge detection
bool waiting_for_first_edge = true;
// Did we detected any modulaiton at all
bool detected_tag_modulation = false;
// Reset the number of NRZ samples and use edge detection to detect them
size_t nrzs = 0;
// Use the current modulation state as starting point
uint8_t tag_modulation = lf_get_tag_modulation();
// Raw demodulation/decoding by sampling edge periods
while (nrzs < HT2_MAX_NRSZ) {
// Get the timing of the next edge in number of wave periods
size_t periods = lf_count_edge_periods(128);
// Are we dealing with the first incoming edge
if (waiting_for_first_edge) {
// Just break out of loop after an initial time-out (tag is probably not available)
if (periods == 0) {
break;
}
if (tag_modulation == 0) {
// hitag replies always start with 11111 == 1010101010, if we see 0
// it means we missed the first period, e.g. if the signal never crossed 0 since reader signal
// so let's add it:
nrz_samples[nrzs++] = tag_modulation ^ 1;
// Register the number of periods that have passed
// we missed the begin of response but we know it happened one period of 16 earlier
resp_start += (periods - 16);
resp_duration = resp_start;
} else {
// Register the number of periods that have passed
resp_start += periods;
resp_duration = resp_start;
}
// Indicate that we have dealt with the first edge
waiting_for_first_edge = false;
// The first edge is always a single NRZ bit, force periods on 16
periods = 16;
// We have received more than 0 periods, so we have detected a tag response
detected_tag_modulation = true;
} else {
// The function lf_count_edge_periods() returns 0 when a time-out occurs
if (periods == 0) {
break;
}
}
// Evaluate the number of periods before the next edge
if (periods > 24 && periods <= 64) {
// Detected two sequential equal bits and a modulation switch
// NRZ modulation: (11 => --|) or (11 __|)
nrz_samples[nrzs++] = tag_modulation;
if (nrzs < HT2_MAX_NRSZ) {
nrz_samples[nrzs++] = tag_modulation;
}
resp_duration += periods;
// Invert tag modulation state
tag_modulation ^= 1;
} else if (periods > 0 && periods <= 24) {
// Detected one bit and a modulation switch
// NRZ modulation: (1 => -|) or (0 _|)
nrz_samples[nrzs++] = tag_modulation;
resp_duration += periods;
tag_modulation ^= 1;
} else {
// The function lf_count_edge_periods() returns > 64 periods, this is not a valid number periods
break;
}
}
// Make sure we always have an even number of samples. This fixes the problem
// of ending the manchester decoding with a zero. See the example below where
// the '|' character is end of modulation
// One at the end: ..._-|_____...
// Zero at the end: ...-_|_____...
// The last modulation change of a zero is not detected, but we should take
// the half period in account, otherwise the demodulator will fail.
if ((nrzs % 2) != 0) {
if (nrzs >= HT2_MAX_NRSZ) {
return false;
}
nrz_samples[nrzs++] = tag_modulation;
}
*samples = nrzs;
return detected_tag_modulation;
}
bool ht2_packbits(uint8_t *nrz_samples, size_t nrzs, uint8_t *rx, size_t *rxlen) {
// Verify if the header consists of five consecutive ones
if (nrzs < 5) {
return false;
}
// detect hitag 2 header
if (memcmp(nrz_samples, "\x01\x01\x01\x01\x01", 5)) {
return false;
}
// Pack the response into a byte array
for (size_t i = 5; i < nrzs && *rxlen < (HITAG_FRAME_LEN << 3); i++) {
uint8_t bit = nrz_samples[i];
// When Manchester detects impossible symbol it writes "7"
if (bit > 1) {
break;
}
rx[*rxlen >> 3] |= bit << (7 - (*rxlen % 8));
*rxlen = *rxlen + 1;
}
// skip spurious bit
if (*rxlen % 8 == 1) {
*rxlen = *rxlen - 1;
}
return true;
}
int ht2_read_uid(uint8_t *uid, bool ledcontrol, bool send_answer, bool keep_field_up) {
g_logging = false;
// keep field up indicates there are more traffic to be done.
if (keep_field_up == false) {
clear_trace();
}
// hitag 2 state machine?
hitag2_init();
// init as reader
lf_init(true, false, true);
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
uint8_t rx[HITAG_FRAME_LEN] = {0};
size_t rxlen = 0; // In number of bits
uint8_t nrz_samples[HT2_MAX_NRSZ];
uint8_t attempt_count = 3;
int res = PM3_EFAILED;
bool turn_on = true;
while (attempt_count && BUTTON_PRESS() == false) {
attempt_count--;
WDT_HIT();
uint32_t command_start = 0, command_duration = 0;
uint32_t response_start = 0, response_duration = 0;
// start AUTH command
size_t txlen = 5;
uint8_t tx[] = {HITAG2_START_AUTH};
// Transmit as reader
ht2_send(turn_on, &command_start, &command_duration, &response_start, tx, txlen, false);
turn_on = false;
// Reset the number of NRZ samples and use edge detection to detect them
size_t nrzs = 0;
// receive raw samples
if (ht2_receive(&response_start, &response_duration, nrz_samples, &nrzs) == false) {
continue;;
}
// Store the transmit frame ( TX ), we do this now at this point, to avoid delay in processing
// and to be able to overwrite the first samples with the trace (since they currently
// still use the same memory space)
LogTraceBits(tx, txlen, command_start, command_start + command_duration, true);
// decode raw samples from Manchester Encoded to bits
manrawdecode(nrz_samples, &nrzs, true, 0);
// pack bits to bytes
if (ht2_packbits(nrz_samples, nrzs, rx, &rxlen) == false) {
continue;
}
// log Receive data
LogTraceBits(rx, rxlen, response_start, response_start + response_duration, false);
if (rxlen != 32) {
continue;
}
// Store received UID
memcpy(tag.sectors[0], rx, 4);
if (uid) {
memcpy(uid, rx, 4);
}
res = PM3_SUCCESS;
break;
}
if (keep_field_up == false) {
lf_finalize(false);
BigBuf_free_keep_EM();
}
if (send_answer) {
reply_ng(CMD_LF_HITAG_READER, res, (uint8_t *)tag.sectors, 4);
}
return res;
}
// This function assumes you have called hitag2_read_uid before to turn on the field :)
// tx = expects bin arrays 0,1 i
// txlen = number of bits to send
// rx = return bin arrys
// rxlen = number of bits returned
int ht2_tx_rx(uint8_t *tx, size_t txlen, uint8_t *rx, size_t *rxlen, bool ledcontrol, bool keep_field_up) {
int res = PM3_EFAILED;
size_t nrzs = 0;
uint8_t samples[HT2_MAX_NRSZ] = {0};
uint32_t command_start = 0, command_duration = 0;
uint32_t response_start = 0, response_duration = 0;
// Transmit as reader
ht2_send(false, &command_start, &command_duration, &response_start, tx, txlen, true);
// receive raw samples
if (ht2_receive(&response_start, &response_duration, samples, &nrzs) == false) {
goto out;
}
// decode raw samples from Manchester Encoded to bits
if (manrawdecode(samples, &nrzs, true, 0)) {
goto out;
}
// pack bits to bytes
if (rx && (ht2_packbits(samples, nrzs, rx, rxlen) == false)) {
goto out;
}
res = PM3_SUCCESS;
out:
if (keep_field_up == false) {
lf_finalize(false);
}
return res;
}
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