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proxmark3/armsrc/hitag2.c
iceman1001 f04be0c044 chg: hitag write - works
2020-01-20 11:58:22 +01:00

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//-----------------------------------------------------------------------------
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Hitag2 emulation
//
// (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
//-----------------------------------------------------------------------------
// Hitag2 complete rewrite of the code
// - Fixed modulation/encoding issues
// - Rewrote code for transponder emulation
// - Added sniffing of transponder communication
// - Added reader functionality
//
// (c) 2012 Roel Verdult
//-----------------------------------------------------------------------------
// Piwi, 2019
// Iceman, 2019
// Anon, 2019
// Doegos, 2020
#include "hitag2.h"
#include "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"
// Successful crypto auth
static bool bCrypto;
// Is in auth stage
static bool bAuthenticating;
// Successful password auth
bool bSelecting;
bool bCollision;
static bool bPwd;
static bool bSuccessful;
static struct hitag2_tag 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] = { 0x0e, 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 HITAG1/HITAGS 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];
uint8_t logdata_0[4], logdata_1[4];
uint8_t nonce[4];
bool key_no;
static uint64_t cipher_state;
static int hitag2_reset(void) {
tag.state = TAG_STATE_RESET;
tag.crypto_active = 0;
return 0;
}
static int hitag2_init(void) {
hitag2_reset();
return 0;
}
// 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_T_STOP 36 /* T_EOF should be > 36 */
#define HITAG_T_LOW 8 /* 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 40 /* T_EOF should be > 36 */
#define HITAG_T_EOF 80 /* T_EOF should be > 36 */
#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_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
static void hitag_send_bit(int bit) {
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
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);
}
LED_A_OFF();
}
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) {
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 05: {
// Always send over the air in the clear plaintext mode
if (rx_air[0] != 0xC0) {
// 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: {
unsigned int sector = (~(((rx[0] << 2) & 0x04) | ((rx[1] >> 6) & 0x03)) & 0x07);
// Verify complement of sector index
if (sector != ((rx[0] >> 3) & 0x07)) {
//DbpString("Transmission error (read/write)");
return;
}
switch (rx[0] & 0xC6) {
// Read command: 11xx x00y
case 0xC0:
memcpy(tx, tag.sectors[sector], 4);
*txlen = 32;
break;
// Inverted Read command: 01xx x10y
case 0x44:
for (size_t i = 0; i < 4; i++) {
tx[i] = tag.sectors[sector][i] ^ 0xff;
}
*txlen = 32;
break;
// Write command: 10xx x01y
case 0x82:
// 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:
Dbprintf("Unknown command: %02x %02x", rx[0], rx[1]);
return;
break;
}
}
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) {
DbpString("Reader password is wrong");
return;
}
*txlen = 32;
memcpy(tx, tag.sectors[3], 4);
}
}
break;
// Received RWD authentication challenge and respnse
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
hitag2_cipher_reset(&tag, rx);
// Check if the authentication was correct
if (!hitag2_cipher_authenticate(&(tag.cs), rx + 4)) {
// The reader failed to authenticate, do nothing
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;
}
// Succesful, but commented out reporting back to the Host, this may delay to much.
// Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x OK!",rx[0],rx[1],rx[2],rx[3],rx[4],rx[5],rx[6],rx[7]);
// 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;
}
// LogTrace(rx, nbytes(rxlen), 0, 0, NULL, false);
// LogTrace(tx, nbytes(txlen), 0, 0, NULL, true);
if (tag.crypto_active) {
hitag2_cipher_transcrypt(&(tag.cs), tx, *txlen / 8, *txlen % 8);
}
}
// sim
static uint32_t hitag_reader_send_bit(int bit) {
uint32_t wait = 0;
LED_A_ON();
// 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(8); // wait for 4-10 times the carrier period
wait += 8;
// 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;
}
/*lf_wait_periods(10);*/
LED_A_OFF();
return wait;
}
// sim
static uint32_t hitag_reader_send_frame(const uint8_t *frame, size_t frame_len) {
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);
}
// 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;
return wait;
}
size_t blocknr;
uint8_t hitag_crc(uint8_t *data, size_t length) {
uint8_t crc = 0xff;
unsigned int byte, bit;
for (byte = 0; byte < ((length + 7) / 8); byte++) {
crc ^= *(data + byte);
bit = length < (8 * (byte + 1)) ? (length % 8) : 8;
while (bit--) {
if (crc & 0x80) {
crc <<= 1;
crc ^= 0x1d;
} else {
crc <<= 1;
}
}
}
return crc;
}
#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)))
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));
}
bool hitag_plain(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool hitag_s) {
uint8_t crc;
*txlen = 0;
switch (rxlen) {
case 0: {
// retry waking up card
/*tx[0] = 0xb0; // Rev 3.0*/
tx[0] = 0x30; // 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: {
if (bCollision) {
// Select card by serial from response
tx[0] = 0x00 | 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 succesful!");
*txlen = 0;
bSuccessful = true;
return false;
}
// read next page of card until done
Dbprintf("Reading page %02u", blocknr);
tx[0] = 0xc0 | 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("Uknown frame length: %d", rxlen);
return false;
}
break;
}
return true;
}
size_t flipped_bit = 0;
uint32_t byte_value = 0;
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] = 0x30; // 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] = 0xe0 | 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] = 0x00 | 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] = 0xa0 | key_no >> 4; // 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 succesful!");
bSuccessful = true;
return false;
}
// TEST
Dbprintf("Succesfully authenticated with logdata:");
Dbhexdump(4, logdata_1, false);
bSuccessful = true;
return false;
// read next page of card until done
tx[0] = 0xe0 | 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("Uknown frame length: %d", rxlen);
return false;
}
break;
}
return true;
}
//-----------------------------------------------------------------------------
// Hitag2 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] = 0x82 | (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] == (0x82 | (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:
DbpString("hitag2_write_page: Unknown state %d");
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 && write) {
if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
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) {
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) {
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) {
DbpString("Read successful!");
bSuccessful = true;
return false;
}
*txlen = 10;
tx[0] = 0xC0 | (blocknr << 3) | ((blocknr ^ 7) >> 2);
tx[1] = ((blocknr ^ 7) << 6);
}
}
break;
// Unexpected response
default: {
Dbprintf("Unknown frame length: %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) {
hitag2_cipher_transcrypt(&cipher_state, rx, rxlen / 8, rxlen % 8);
}
if (bCrypto && !bAuthenticating && write) {
if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
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) {
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) {
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;
Dbprintf("hitag2_crypto: key=0x%x%x uid=0x%x", (uint32_t)((REV64(ui64key)) >> 32), (uint32_t)((REV64(ui64key)) & 0xffffffff), REV32(ui32uid));
cipher_state = _hitag2_init(REV64(ui64key), REV32(ui32uid), 0);
// PRN
memset(tx, 0x00, 4);
// Secret data
memset(tx + 4, 0xff, 4);
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)) {
return false;
}
break;
}
}
// stage 2+, got data block
else {
// Store the received block
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
}
if (blocknr > 7) {
DbpString("Read successful!");
bSuccessful = true;
return false;
} else {
*txlen = 10;
tx[0] = 0xc0 | (blocknr << 3) | ((blocknr ^ 7) >> 2);
tx[1] = ((blocknr ^ 7) << 6);
}
}
}
break;
// Unexpected response
default: {
Dbprintf("Unknown frame length: %d", rxlen);
return false;
}
break;
}
}
if (bCrypto) {
// We have to return now to avoid double encryption
if (!bAuthenticating) {
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) {
// 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) {
DbpString("Authentication failed!");
return false;
}
*txlen = 5;
memcpy(tx, "\xC0", nbytes(*txlen));
}
break;
// Received UID, crypto tag answer
case 32: {
if (!bCrypto) {
*txlen = 64;
memcpy(tx, NrAr, 8);
bCrypto = true;
} else {
DbpString("Authentication successful!");
return true;
}
}
break;
// Unexpected response
default: {
Dbprintf("Unknown frame length: %d", rxlen);
return false;
}
break;
}
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 authentiations 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) {
*txlen = 64;
memcpy(tx, NrAr, 8);
bCrypto = true;
} else {
Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x 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: %d", rxlen);
return false;
}
break;
}
return true;
}
static bool hitag2_read_uid(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: {
// Just starting or if there is no answer
*txlen = 5;
memcpy(tx, "\xC0", nbytes(*txlen));
}
break;
// Received UID
case 32: {
// Check if we received answer tag (at)
if (bAuthenticating) {
bAuthenticating = false;
} else {
// Store the received block
memcpy(tag.sectors[blocknr], rx, 4);
blocknr++;
Dbhexdump(4, rx, false);
}
if (blocknr > 0) {
DbpString("Read successful!");
bSuccessful = true;
return false;
}
}
break;
// Unexpected response
default: {
Dbprintf("Unknown frame length: %d", rxlen);
return false;
}
break;
}
return true;
}
// Hitag2 Sniffing
void SniffHitag(void) {
LEDsoff();
StopTicks();
FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
BigBuf_free();
BigBuf_Clear_ext(false);
clear_trace();
set_tracing(true);
auth_table_len = 0;
auth_table_pos = 0;
auth_table = (uint8_t *)BigBuf_malloc(AUTH_TABLE_LENGTH);
memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
DbpString("Starting Hitag2 sniffing");
LED_D_ON();
lf_init(false);
logging = false;
size_t periods = 0;
uint8_t periods_bytes[4];
/*bool waiting_for_first_edge = true;*/
LED_C_ON();
while (!BUTTON_PRESS() && !data_available()) {
WDT_HIT();
// Receive frame, watch for at most T0*EOF periods
lf_reset_counter();
// Wait "infinite" for reader modulation
periods = lf_detect_gap(20000);
// Test if we detected the first reader modulation edge
if (periods != 0) {
if (logging == false) {
logging = true;
LED_D_ON();
}
}
/*lf_count_edge_periods(10000);*/
while ((periods = lf_detect_gap(64)) != 0) {
num_to_bytes(periods, 4, periods_bytes);
LogTrace(periods_bytes, 4, 0, 0, NULL, true);
}
/*
// Check if frame was captured
if (rxlen > 0) {
// frame_count++;
LogTrace(rx, nbytes(rxlen), response, 0, NULL, reader_frame);
// Check if we recognize a valid authentication attempt
if (nbytes(rxlen) == 8) {
// Store the authentication attempt
if (auth_table_len < (AUTH_TABLE_LENGTH - 8)) {
memcpy(auth_table + auth_table_len, rx, 8);
auth_table_len += 8;
}
}
*/
}
lf_finalize();
StartTicks();
DbpString("Hitag2 sniffing finish. Use `lf hitag list` for annotations");
}
// Hitag2 simulation
void SimulateHitagTag(bool tag_mem_supplied, uint8_t *data) {
StopTicks();
// int frame_count = 0;
int response = 0, overflow = 0;
uint8_t rx[HITAG_FRAME_LEN];
size_t rxlen = 0;
uint8_t tx[HITAG_FRAME_LEN];
size_t txlen = 0;
FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
BigBuf_free();
BigBuf_Clear_ext(false);
clear_trace();
set_tracing(true);
auth_table_len = 0;
auth_table_pos = 0;
auth_table = BigBuf_malloc(AUTH_TABLE_LENGTH);
memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
// Reset the received frame, frame count and timing info
memset(rx, 0x00, sizeof(rx));
DbpString("Starting Hitag2 simulation");
LED_D_ON();
hitag2_init();
if (tag_mem_supplied) {
DbpString("Loading hitag2 memory...");
memcpy((uint8_t *)tag.sectors, data, 48);
}
uint32_t block = 0;
for (size_t i = 0; i < 12; i++) {
for (size_t j = 0; j < 4; j++) {
block <<= 8;
block |= tag.sectors[i][j];
}
Dbprintf("| %d | %08x |", i, block);
}
// Set up simulator mode, frequency divisor which will drive the FPGA
// and analog mux selection.
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, LF_DIVISOR_125); //125kHz
SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
// 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 at default, which means release resistance
LOW(GPIO_SSC_DOUT);
// Enable Peripheral Clock for
// TIMER_CLOCK0, used to measure exact timing before answering
// TIMER_CLOCK1, used to capture edges of the tag frames
AT91C_BASE_PMC->PMC_PCER |= (1 << AT91C_ID_TC0) | (1 << AT91C_ID_TC1);
AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
// Disable timer during configuration
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
// TC0: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), no triggers
AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK;
// TC1: 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_RISING | AT91C_TC_ABETRG | AT91C_TC_LDRA_RISING;
// Enable and reset counter
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
// synchronized startup procedure
while (AT91C_BASE_TC0->TC_CV > 0) {}; // wait until TC0 returned to zero
while (!BUTTON_PRESS() && !data_available()) {
// Watchdog hit
WDT_HIT();
// 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;
// Reset timer every frame, we have to capture the last edge for timing
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
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);
} 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 {
// Ignore wierd value, is to small to mean anything
}
}
}
// Check if frame was captured
if (rxlen > 4) {
// frame_count++;
LogTrace(rx, nbytes(rxlen), response, response, NULL, true);
// Disable timer 1 with external trigger to avoid triggers during our own modulation
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
// 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
while (AT91C_BASE_TC0->TC_CV < HITAG_T0 * (HITAG_T_WAIT_1_MIN - HITAG_T_LOW));
// Send and store the tag answer (if there is any)
if (txlen) {
hitag_send_frame(tx, txlen);
LogTrace(tx, nbytes(txlen), 0, 0, NULL, false);
}
// Reset the received frame and response timing info
memset(rx, 0x00, sizeof(rx));
response = 0;
// Enable and reset external trigger in timer for capturing future frames
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
LED_B_OFF();
}
// Reset the frame length
rxlen = 0;
// Save the timer overflow, will be 0 when frame was received
overflow += (AT91C_BASE_TC1->TC_CV / HITAG_T0);
// Reset the timer to restart while-loop that receives frames
AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
}
LEDsoff();
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
set_tracing(false);
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
// release allocated memory from BigBuff.
BigBuf_free();
StartTicks();
DbpString("Sim Stopped");
}
void ReaderHitag(hitag_function htf, hitag_data *htd) {
StopTicks();
int frame_count = 0;
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;
int t_wait_1_guard = 8;
int t_wait_2;
size_t tag_size;
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();
DbpString("Starting Hitag reader family");
// Check configuration
switch (htf) {
case RHT1F_PLAIN: {
Dbprintf("Read public blocks in plain mode");
// this part will be unreadable
memset(tag.sectors + 2, 0x0, 30);
blocknr = 0;
}
break;
case RHT1F_AUTHENTICATE: {
Dbprintf("Read all blocks in authed mode");
memcpy(nonce, htd->ht1auth.nonce, 4);
memcpy(key, htd->ht1auth.key, 4);
memcpy(logdata_0, htd->ht1auth.logdata_0, 4);
memcpy(logdata_1, htd->ht1auth.logdata_1, 4);
// TEST
memset(nonce, 0x0, 4);
memset(logdata_1, 0x00, 4);
byte_value = 0;
key_no = htd->ht1auth.key_no;
Dbprintf("Authenticating using key #%d:", key_no);
Dbhexdump(4, key, false);
DbpString("Nonce:");
Dbhexdump(4, nonce, false);
DbpString("Logdata_0:");
Dbhexdump(4, logdata_0, false);
DbpString("Logdata_1:");
Dbhexdump(4, logdata_1, false);
blocknr = 0;
}
break;
case RHT2F_PASSWORD: {
Dbprintf("List identifier in password mode");
memcpy(password, htd->pwd.password, 4);
blocknr = 0;
bPwd = false;
bAuthenticating = false;
break;
}
case RHT2F_AUTHENTICATE: {
DbpString("Authenticating using nr,ar pair:");
memcpy(NrAr, htd->auth.NrAr, 8);
Dbhexdump(8, NrAr, false);
bCrypto = false;
bAuthenticating = false;
break;
}
case RHT2F_CRYPTO: {
DbpString("Authenticating using key:");
memcpy(key, htd->crypto.key, 6); //HACK; 4 or 6?? I read both in the code.
Dbhexdump(6, key, false);
DbpString("Nonce:");
Dbhexdump(4, nonce, false);
memcpy(nonce, htd->crypto.data, 4);
blocknr = 0;
bCrypto = false;
bAuthenticating = false;
break;
}
case RHT2F_TEST_AUTH_ATTEMPTS: {
Dbprintf("Testing %d authentication attempts", (auth_table_len / 8));
auth_table_pos = 0;
memcpy(NrAr, auth_table, 8);
bCrypto = false;
break;
}
case RHT2F_UID_ONLY: {
blocknr = 0;
bCrypto = false;
bAuthenticating = false;
break;
}
default: {
Dbprintf("Error, unknown function: %d", htf);
set_tracing(false);
StartTicks();
return;
}
}
LED_D_ON();
hitag2_init();
// init as reader
lf_init(true);
uint8_t attempt_count = 0;
// Tag specific configuration settings (sof, timings, etc.)
if (htf < 10) {
// hitagS settings
t_wait_1 = 204;
t_wait_2 = 128;
/*tag_size = 256;*/
flipped_bit = 0;
tag_size = 8;
DbpString("Configured for hitagS reader");
} else if (htf < 20) {
// hitag1 settings
t_wait_1 = 204;
t_wait_2 = 128;
tag_size = 256;
flipped_bit = 0;
DbpString("Configured for hitag1 reader");
} else if (htf < 30) {
// hitag2 settings
t_wait_1 = HITAG_T_WAIT_1_MIN;
t_wait_2 = HITAG_T_WAIT_2_MIN;
tag_size = 48;
DbpString("Configured for hitag2 reader");
} else {
Dbprintf("Error, unknown hitag reader type: %d", htf);
return;
}
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;
while (!bStop && !BUTTON_PRESS() && !data_available()) {
WDT_HIT();
// By default reset the transmission buffer
tx = txbuf;
switch (htf) {
case RHT1F_PLAIN: {
bStop = !hitag_plain(rx, rxlen, tx, &txlen, false);
}
break;
case RHT1F_AUTHENTICATE: {
bStop = !hitag1_authenticate(rx, rxlen, tx, &txlen);
}
break;
case RHT2F_PASSWORD: {
bStop = !hitag2_password(rx, rxlen, tx, &txlen, false);
break;
}
case RHT2F_AUTHENTICATE: {
bStop = !hitag2_authenticate(rx, rxlen, tx, &txlen);
break;
}
case RHT2F_CRYPTO: {
bStop = !hitag2_crypto(rx, rxlen, tx, &txlen, false);
break;
}
case RHT2F_TEST_AUTH_ATTEMPTS: {
bStop = !hitag2_test_auth_attempts(rx, rxlen, tx, &txlen);
break;
}
case RHT2F_UID_ONLY: {
bStop = !hitag2_read_uid(rx, rxlen, tx, &txlen);
attempt_count++; //attempt 3 times to get uid then quit
if (!bStop && attempt_count == 3)
bStop = true;
break;
}
default: {
Dbprintf("Error, unknown function: %d", htf);
goto out;
}
}
// 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) {
//Dbprintf("Detected timeout after [%d] 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;
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
//Dbprintf("Detected unexpected period count: %d", 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)
if (txlen > 0) {
frame_count++;
LogTrace(tx, nbytes(txlen), command_start, command_start + command_duration, NULL, 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) 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) {
nrz_samples[nrzs++] = tag_modulation;
}
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) {
//Dbprintf("Detected unexpected number of manchester decoded samples [%d]", nrzs);
break;
} else {
size_t i;
for (i = 0; i < 5; i++) {
if (nrz_samples[i] != 1) {
Dbprintf("Detected incorrect header, the bit [%d] 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; i++) {
uint8_t bit = nrz_samples[i];
if (bit > 1) { // When Manchester detects impossible symbol it writes "7"
//Dbprintf("Error in Manchester decoding, abort");
break;
}
rx[rxlen / 8] |= bit << (7 - (rxlen % 8));
rxlen++;
}
if (rxlen % 8 == 1) // skip spurious bit
rxlen--;
// Check if frame was captured and store it
if (rxlen > 0) {
frame_count++;
// if (bCollision){
// // AC decoding hack
// fix_ac_decoding(rx, 64);
// rxlen = 32;
// }
LogTrace(rx, nbytes(rxlen), response_start, response_start + response_duration, NULL, false);
// TODO when using cumulative time for command_start, pm3 doesn't reply anymore, e.g. on lf hitag read 23 4F4E4D494B52
command_start = response_start + response_duration;
// command_start = 0;
// Dbhexdump(nbytes(rxlen), rx, false);
}
}
out:
lf_finalize();
Dbprintf("TX/RX frames recorded: %u", frame_count);
// release allocated memory from BigBuff.
BigBuf_free();
StartTicks();
if (bSuccessful)
reply_old(CMD_ACK, bSuccessful, 0, 0, (uint8_t *)tag.sectors, tag_size);
else
reply_mix(CMD_ACK, bSuccessful, 0, 0, 0, 0);
}
void WriterHitag(hitag_function htf, hitag_data *htd, int page) {
StopTicks();
int frame_count = 0;
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;
int t_wait_1_guard = 8;
int t_wait_2;
size_t tag_size;
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();
DbpString("Starting Hitag writer family");
// Check configuration
switch (htf) {
case WHT2F_CRYPTO: {
DbpString("Authenticating using key:");
memcpy(key, htd->crypto.key, 6); //HACK; 4 or 6?? I read both in the code.
memcpy(writedata, htd->crypto.data, 4);
Dbhexdump(6, key, false);
blocknr = page;
bCrypto = false;
bAuthenticating = false;
writestate = WRITE_STATE_START;
}
break;
case WHT2F_PASSWORD: {
DbpString("Authenticating using password:");
memcpy(password, htd->pwd.password, 4);
memcpy(writedata, htd->crypto.data, 4);
Dbhexdump(4, password, false);
blocknr = page;
bPwd = false;
bAuthenticating = false;
writestate = WRITE_STATE_START;
}
break;
default: {
Dbprintf("Error, unknown function: %d", htf);
StartTicks();
return;
}
break;
}
LED_D_ON();
hitag2_init();
// init as reader
lf_init(true);
// Tag specific configuration settings (sof, timings, etc.)
if (htf < 10) {
// hitagS settings
t_wait_1 = 204;
t_wait_2 = 128;
/*tag_size = 256;*/
flipped_bit = 0;
tag_size = 8;
DbpString("Configured for hitagS writer");
} else if (htf < 20) {
// hitag1 settings
t_wait_1 = 204;
t_wait_2 = 128;
tag_size = 256;
flipped_bit = 0;
DbpString("Configured for hitag1 writer");
} else if (htf < 30) {
// hitag2 settings
t_wait_1 = HITAG_T_WAIT_1_MIN;
t_wait_2 = HITAG_T_WAIT_2_MIN;
tag_size = 48;
DbpString("Configured for hitag2 writer");
} else {
Dbprintf("Error, unknown hitag writer type: %d", htf);
return;
}
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;
while (!bStop && !BUTTON_PRESS() && !data_available()) {
WDT_HIT();
// By default reset the transmission buffer
tx = txbuf;
switch (htf) {
case WHT2F_CRYPTO: {
bStop = !hitag2_crypto(rx, rxlen, tx, &txlen, true);
break;
}
case WHT2F_PASSWORD: {
bStop = !hitag2_password(rx, rxlen, tx, &txlen, true);
break;
}
default: {
Dbprintf("Error, unknown function: %d", htf);
goto out;
}
}
// 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) {
//Dbprintf("Detected timeout after [%d] 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;
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
//Dbprintf("Detected unexpected period count: %d", 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)
if (txlen > 0) {
frame_count++;
LogTrace(tx, nbytes(txlen), command_start, command_start + command_duration, NULL, 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) 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) {
nrz_samples[nrzs++] = tag_modulation;
}
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) {
break;
} else {
size_t i;
for (i = 0; i < 5; i++) {
if (nrz_samples[i] != 1) {
Dbprintf("Detected incorrect header, the bit [%d] 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; i++) {
uint8_t bit = nrz_samples[i];
if (bit > 1) { // When Manchester detects impossible symbol it writes "7"
break;
}
rx[rxlen / 8] |= bit << (7 - (rxlen % 8));
rxlen++;
}
if (rxlen % 8 == 1) // skip spurious bit
rxlen--;
// Check if frame was captured and store it
if (rxlen > 0) {
frame_count++;
LogTrace(rx, nbytes(rxlen), response_start, response_start + response_duration, NULL, false);
command_start = 0;
}
}
out:
lf_finalize();
Dbprintf("TX/RX frames recorded: %u", frame_count);
// release allocated memory from BigBuff.
BigBuf_free();
StartTicks();
reply_mix(CMD_ACK, bSuccessful, 0, 0, (uint8_t *)tag.sectors, tag_size);
}
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