//-----------------------------------------------------------------------------
-// (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
-//
// 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
+// Hitag2 emulation (preliminary test version)
//
-// Contains state and functions for an emulated Hitag2 tag. Offers an entry
-// point to handle commands, needs a callback to send response.
+// (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
+//-----------------------------------------------------------------------------
+// Hitag2 complete rewrite of the code
+// - Fixed modulation/encoding issues
+// - Rewrote code for transponder emulation
+// - Added snooping of transponder communication
+// - Added reader functionality
+//
+// (c) 2012 Roel Verdult
//-----------------------------------------------------------------------------
#include "proxmark3.h"
#include "hitag2.h"
#include "string.h"
-struct hitag2_cipher_state {
- uint64_t state;
-};
+static bool bQuiet;
+
+bool bCrypto;
+bool bPwd;
struct hitag2_tag {
uint32_t uid;
enum {
- TAG_STATE_RESET, // Just powered up, awaiting GetSnr
- TAG_STATE_ACTIVATING, // In activation phase (password mode), sent UID, awaiting reader password
- TAG_STATE_AUTHENTICATING, // In activation phase (crypto mode), awaiting reader authentication
- TAG_STATE_ACTIVATED, // Activation complete, awaiting read/write commands
- TAG_STATE_WRITING, // In write command, awaiting sector contents to be written
+ TAG_STATE_RESET = 0x01, // Just powered up, awaiting GetSnr
+ TAG_STATE_ACTIVATING = 0x02 , // In activation phase (password mode), sent UID, awaiting reader password
+ TAG_STATE_ACTIVATED = 0x03, // Activation complete, awaiting read/write commands
+ TAG_STATE_WRITING = 0x04, // In write command, awaiting sector contents to be written
} state;
unsigned int active_sector;
- char crypto_active;
- struct hitag2_cipher_state cs;
- char sectors[8][4];
+ byte_t crypto_active;
+ uint64_t cs;
+ byte_t sectors[12][4];
};
-static void hitag2_cipher_reset(struct hitag2_tag *tag, const char *challenge);
-static int hitag2_cipher_authenticate(struct hitag2_cipher_state *cs, const char *authenticator);
-static int hitag2_cipher_transcrypt(struct hitag2_cipher_state *cs, char *data, unsigned int bytes, unsigned int bits);
-
static struct hitag2_tag tag;
static const struct hitag2_tag resetdata = {
- .state = TAG_STATE_RESET,
- .sectors = { // Password mode: | Crypto mode:
- [0] = { 0x35, 0x33, 0x70, 0x11}, // 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, 'H', 'T'}, // Configuration, password TAG | Configuration, password 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
+ },
};
-int hitag2_reset(void)
-{
- tag.state = TAG_STATE_RESET;
- tag.crypto_active = 0;
- return 0;
-}
-
-int hitag2_init(void)
-{
- memcpy(&tag, &resetdata, sizeof(tag));
- hitag2_reset();
- return 0;
-}
-
-int hitag2_handle_command(const char* data, const int length, hitag2_response_callback_t cb, void *cb_cookie)
-{
- (void)data; (void)length; (void)cb; (void)cb_cookie;
- int retry = 0, done = 0, result=0;
- char temp[10];
-
- if(tag.crypto_active && length < sizeof(temp)*8) {
- /* Decrypt command */
- memcpy(temp, data, (length+7)/8);
- hitag2_cipher_transcrypt(&(tag.cs), temp, length/8, length%8);
- data = temp;
- }
-
-
-handle_command_retry:
- switch(tag.state) {
- case TAG_STATE_RESET:
- if(length == 5 && data[0] == 0xC0) {
- /* Received 11000 from the reader, request for UID, send UID */
- result=cb(tag.sectors[0], sizeof(tag.sectors[0])*8, 208, cb_cookie);
- done=1;
- if(tag.sectors[3][0] & 0x08) {
- tag.state=TAG_STATE_AUTHENTICATING;
- } else {
- tag.state=TAG_STATE_ACTIVATING;
- }
- }
- break;
- case TAG_STATE_ACTIVATING:
- if(length == 0x20) {
- /* Received RWD password, respond with configuration and our password */
- result=cb(tag.sectors[3], sizeof(tag.sectors[3])*8, 208, cb_cookie);
- done=1;
- tag.state=TAG_STATE_ACTIVATED;
- }
- break;
- case TAG_STATE_AUTHENTICATING:
- if(length == 0x40) {
- /* Received initialisation vector || authentication token, fire up cipher, send our password */
- hitag2_cipher_reset(&tag, data);
- if(hitag2_cipher_authenticate(&(tag.cs), data+4)) {
- char response_enc[4];
- memcpy(response_enc, tag.sectors[3], 4);
- hitag2_cipher_transcrypt(&(tag.cs), response_enc, 4, 0);
- result=cb(response_enc, 4*8, 208, cb_cookie);
- done=1;
- tag.crypto_active = 1;
- tag.state = TAG_STATE_ACTIVATED;
- } else {
- /* The reader failed to authenticate, do nothing */
- DbpString("Reader authentication failed");
- }
- }
- break;
- case TAG_STATE_ACTIVATED:
- if(length == 10) {
- if( ((data[0] & 0xC0) == 0xC0) && ((data[0] & 0x06) == 0) ) {
- /* Read command: 11xx x00y yy with yyy == ~xxx, xxx is sector number */
- unsigned int sector = (~( ((data[0]<<2)&0x04) | ((data[1]>>6)&0x03) ) & 0x07);
- if(sector == ( (data[0]>>3)&0x07 ) ) {
- memcpy(temp, tag.sectors[sector], 4);
- if(tag.crypto_active) {
- hitag2_cipher_transcrypt(&(tag.cs), temp, 4, 0);
- }
- /* Respond with contents of sector sector */
- result = cb(temp, 4*8, 208, cb_cookie);
- done=1;
- } else {
- /* transmission error */
- DbpString("Transmission error (read) in activated state");
- }
- } else if( ((data[0] & 0xC0) == 0x80) && ((data[0] & 0x06) == 2) ) {
- /* Write command: 10xx x01y yy with yyy == ~xxx, xxx is sector number */
- unsigned int sector = (~( ((data[0]<<2)&0x04) | ((data[1]>>6)&0x03) ) & 0x07);
- if(sector == ( (data[0]>>3)&0x07 ) ) {
- /* Prepare write, acknowledge by repeating command */
- if(tag.crypto_active) {
- hitag2_cipher_transcrypt(&(tag.cs), temp, length/8, length%8);
- }
- result = cb(data, length, 208, cb_cookie);
- done=1;
- tag.active_sector = sector;
- tag.state=TAG_STATE_WRITING;
- } else {
- /* transmission error */
- DbpString("Transmission error (write) in activated state");
- }
- }
-
- }
- case TAG_STATE_WRITING:
- if(length == 32) {
- /* These are the sector contents to be written. We don't have to do anything else. */
- memcpy(tag.sectors[tag.active_sector], data, length/8);
- tag.state=TAG_STATE_ACTIVATED;
- done=1;
- }
- }
+//#define TRACE_LENGTH 3000
+//uint8_t *trace = (uint8_t *) BigBuf;
+//int traceLen = 0;
+//int rsamples = 0;
- if(!done && !retry) {
- /* We didn't respond, maybe our state is faulty. Reset and try again. */
- retry=1;
- if(tag.crypto_active) {
- /* Restore undeciphered data */
- memcpy(temp, data, (length+7)/8);
- }
- hitag2_reset();
- goto handle_command_retry;
- }
+#define AUTH_TABLE_OFFSET FREE_BUFFER_OFFSET
+#define AUTH_TABLE_LENGTH FREE_BUFFER_SIZE
+byte_t* auth_table = (byte_t *)BigBuf+AUTH_TABLE_OFFSET;
+size_t auth_table_pos = 0;
+size_t auth_table_len = AUTH_TABLE_LENGTH;
- return result;
-}
+byte_t password[4];
+byte_t NrAr[8];
/* Following is a modified version of cryptolib.com/ciphers/hitag2/ */
// Software optimized 48-bit Philips/NXP Mifare Hitag2 PCF7936/46/47/52 stream cipher algorithm by I.C. Wiener 2006-2007.
return c;
}
+size_t nbytes(size_t nbits) {
+ return (nbits/8)+((nbits%8)>0);
+}
+
+int hitag2_reset(void)
+{
+ tag.state = TAG_STATE_RESET;
+ tag.crypto_active = 0;
+ return 0;
+}
-/* Cipher/tag glue code: */
+int hitag2_init(void)
+{
+ memcpy(&tag, &resetdata, sizeof(tag));
+ hitag2_reset();
+ return 0;
+}
-static void hitag2_cipher_reset(struct hitag2_tag *tag, const char *iv)
+static void hitag2_cipher_reset(struct hitag2_tag *tag, const byte_t *iv)
{
uint64_t key = ((uint64_t)tag->sectors[2][2]) |
((uint64_t)tag->sectors[2][3] << 8) |
(((uint32_t)(iv[1])) << 8) |
(((uint32_t)(iv[2])) << 16) |
(((uint32_t)(iv[3])) << 24);
- tag->cs.state = _hitag2_init(rev64(key), rev32(uid), rev32(iv_));
+ tag->cs = _hitag2_init(rev64(key), rev32(uid), rev32(iv_));
}
-static int hitag2_cipher_authenticate(struct hitag2_cipher_state *cs, const char *authenticator_is)
+static int hitag2_cipher_authenticate(uint64_t* cs, const byte_t *authenticator_is)
{
- char authenticator_should[4];
- authenticator_should[0] = ~_hitag2_byte(&(cs->state));
- authenticator_should[1] = ~_hitag2_byte(&(cs->state));
- authenticator_should[2] = ~_hitag2_byte(&(cs->state));
- authenticator_should[3] = ~_hitag2_byte(&(cs->state));
- return memcmp(authenticator_should, authenticator_is, 4) == 0;
+ byte_t authenticator_should[4];
+ authenticator_should[0] = ~_hitag2_byte(cs);
+ authenticator_should[1] = ~_hitag2_byte(cs);
+ authenticator_should[2] = ~_hitag2_byte(cs);
+ authenticator_should[3] = ~_hitag2_byte(cs);
+ return (memcmp(authenticator_should, authenticator_is, 4) == 0);
}
-static int hitag2_cipher_transcrypt(struct hitag2_cipher_state *cs, char *data, unsigned int bytes, unsigned int bits)
+static int hitag2_cipher_transcrypt(uint64_t* cs, byte_t *data, unsigned int bytes, unsigned int bits)
{
int i;
- for(i=0; i<bytes; i++) data[i] ^= _hitag2_byte(&(cs->state));
- for(i=0; i<bits; i++) data[bytes] ^= _hitag2_round(&(cs->state)) << (7-i);
+ for(i=0; i<bytes; i++) data[i] ^= _hitag2_byte(cs);
+ for(i=0; i<bits; i++) data[bytes] ^= _hitag2_round(cs) << (7-i);
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
+#define T0 192
+
+#define SHORT_COIL() LOW(GPIO_SSC_DOUT)
+#define OPEN_COIL() HIGH(GPIO_SSC_DOUT)
+
+#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_1_MIN 25 /* 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_1 200 /* T_wresp should be 199..206 */
+#define HITAG_T_WAIT_2 90 /* T_wresp should be 199..206 */
+#define HITAG_T_WAIT_MAX 300 /* bit more than HITAG_T_WAIT_1 + HITAG_T_WAIT_2 */
+
+#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 < T0*HITAG_T_TAG_HALF_PERIOD);
+ HIGH(GPIO_SSC_DOUT);
+ while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
+ } else {
+ // Manchester: Loaded, then unloaded |--__|
+ HIGH(GPIO_SSC_DOUT);
+ while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
+ LOW(GPIO_SSC_DOUT);
+ while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
+ }
+ LED_A_OFF();
+}
+
+static void hitag_send_frame(const byte_t* frame, size_t frame_len)
+{
+ // Send start of frame
+ for(size_t i=0; i<5; i++) {
+ 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);
+}
+
+void hitag2_handle_reader_command(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen)
+{
+ byte_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("Uknown 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,false);
+// LogTrace(tx,nbytes(*txlen),0,0,true);
+
+ if(tag.crypto_active) {
+ hitag2_cipher_transcrypt(&(tag.cs), tx, *txlen/8, *txlen%8);
+ }
+}
+
+static void hitag_reader_send_bit(int bit) {
+ LED_A_ON();
+ // Reset clock for the next bit
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
+
+ // Binary puls 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 the field
+ HIGH(GPIO_SSC_DOUT);
+
+ // Wait for 4-10 times the carrier period
+ while(AT91C_BASE_TC0->TC_CV < T0*6);
+ // SpinDelayUs(8*8);
+
+ // Disable modulation, just activates the field again
+ LOW(GPIO_SSC_DOUT);
+
+ if(bit == 0) {
+ // Zero bit: |_-|
+ while(AT91C_BASE_TC0->TC_CV < T0*22);
+ // SpinDelayUs(16*8);
+ } else {
+ // One bit: |_--|
+ while(AT91C_BASE_TC0->TC_CV < T0*28);
+ // SpinDelayUs(22*8);
+ }
+ LED_A_OFF();
+}
+
+static void hitag_reader_send_frame(const byte_t* frame, size_t frame_len)
+{
+ // Send the content of the frame
+ for(size_t i=0; i<frame_len; i++) {
+ hitag_reader_send_bit((frame[i/8] >> (7-(i%8)))&1);
+ }
+ // Send EOF
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
+ // Enable modulation, which means, drop the the field
+ HIGH(GPIO_SSC_DOUT);
+ // Wait for 4-10 times the carrier period
+ while(AT91C_BASE_TC0->TC_CV < T0*6);
+ // Disable modulation, just activates the field again
+ LOW(GPIO_SSC_DOUT);
+}
+
+bool hitag2_password(byte_t* rx, const size_t rxlen, byte_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 (after sending password)
+ if (bPwd) {
+ DbpString("Password failed!");
+ return false;
+ }
+ *txlen = 5;
+ memcpy(tx,"\xc0",nbytes(*txlen));
+ } break;
+
+ // Received UID, tag password
+ case 32: {
+ if (!bPwd) {
+ *txlen = 32;
+ memcpy(tx,password,4);
+ bPwd = true;
+ } else {
+ DbpString("Password succesful!");
+ // We are done... for now
+ return false;
+ }
+ } break;
+
+ // Unexpected response
+ default: {
+ Dbprintf("Uknown frame length: %d",rxlen);
+ return false;
+ } break;
+ }
+ return true;
+}
+
+bool hitag2_authenticate(byte_t* rx, const size_t rxlen, byte_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 succesful!");
+ // We are done... for now
+ return false;
+ }
+ } break;
+
+ // Unexpected response
+ default: {
+ Dbprintf("Uknown frame length: %d",rxlen);
+ return false;
+ } break;
+ }
+
+ return true;
+}
+
+bool hitag2_test_auth_attempts(byte_t* rx, const size_t rxlen, byte_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!",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);
+ }
+ *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("Uknown frame length: %d",rxlen);
+ return false;
+ } break;
+ }
+
+ return true;
+}
+
+void SnoopHitag(uint32_t type) {
+ int frame_count;
+ int response;
+ int overflow;
+ bool rising_edge;
+ bool reader_frame;
+ int lastbit;
+ bool bSkip;
+ int tag_sof;
+ byte_t rx[HITAG_FRAME_LEN];
+ size_t rxlen=0;
+
+ // Clean up trace and prepare it for storing frames
+ iso14a_set_tracing(TRUE);
+ iso14a_clear_trace();
+
+ auth_table_len = 0;
+ auth_table_pos = 0;
+ memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
+
+ DbpString("Starting Hitag2 snoop");
+ LED_D_ON();
+
+ // Set up eavesdropping mode, frequency divisor which will drive the FPGA
+ // and analog mux selection.
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
+ 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, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
+ // external trigger rising edge, load RA on rising edge of TIOA.
+ uint32_t t1_channel_mode = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_BOTH | AT91C_TC_ABETRG | AT91C_TC_LDRA_BOTH;
+ AT91C_BASE_TC1->TC_CMR = t1_channel_mode;
+
+ // Enable and reset counter
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+
+ // Reset the received frame, frame count and timing info
+ memset(rx,0x00,sizeof(rx));
+ frame_count = 0;
+ response = 0;
+ overflow = 0;
+ reader_frame = false;
+ lastbit = 1;
+ bSkip = true;
+ tag_sof = 4;
+
+ while(!BUTTON_PRESS()) {
+ // Watchdog hit
+ WDT_HIT();
+
+ // Receive frame, watch for at most T0*EOF periods
+ while (AT91C_BASE_TC1->TC_CV < 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/T0);
+
+ // 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 && rising_edge && ra < HITAG_T_TAG_CAPTURE_ONE_HALF) {
+ // Switch from tag to reader capture
+ LED_C_OFF();
+ reader_frame = true;
+ memset(rx,0x00,sizeof(rx));
+ 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) {
+ 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
+ }
+ } else {
+ 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 recieve 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) {
+ 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++;
+ }
+ } else {
+ // Ignore wierd value, is to small to mean anything
+ }
+ }
+ }
+ }
+
+ // Check if frame was captured
+ if(rxlen > 0) {
+ frame_count++;
+ if (!LogTrace(rx,nbytes(rxlen),response,0,reader_frame)) {
+ DbpString("Trace full");
+ break;
+ }
+
+ // 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;
+ }
+ }
+
+ // Reset the received frame and response timing info
+ memset(rx,0x00,sizeof(rx));
+ response = 0;
+ reader_frame = false;
+ lastbit = 1;
+ bSkip = true;
+ tag_sof = 4;
+ overflow = 0;
+
+ LED_B_OFF();
+ LED_C_OFF();
+ } else {
+ // Save the timer overflow, will be 0 when frame was received
+ overflow += (AT91C_BASE_TC1->TC_CV/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;
+ }
+ LED_A_ON();
+ LED_B_OFF();
+ LED_C_OFF();
+ LED_D_OFF();
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+ LED_A_OFF();
+
+// Dbprintf("frame received: %d",frame_count);
+// Dbprintf("Authentication Attempts: %d",(auth_table_len/8));
+// DbpString("All done");
+}
+
+void SimulateHitagTag(bool tag_mem_supplied, byte_t* data) {
+ int frame_count;
+ int response;
+ int overflow;
+ byte_t rx[HITAG_FRAME_LEN];
+ size_t rxlen=0;
+ byte_t tx[HITAG_FRAME_LEN];
+ size_t txlen=0;
+ bool bQuitTraceFull = false;
+ bQuiet = false;
+
+ // Clean up trace and prepare it for storing frames
+ iso14a_set_tracing(TRUE);
+ iso14a_clear_trace();
+ auth_table_len = 0;
+ auth_table_pos = 0;
+ memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
+
+ DbpString("Starting Hitag2 simulation");
+ LED_D_ON();
+ hitag2_init();
+
+ if (tag_mem_supplied) {
+ DbpString("Loading hitag2 memory...");
+ memcpy((byte_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, 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 at default, which means release resistance
+ LOW(GPIO_SSC_DOUT);
+
+ // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
+ AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
+
+ // 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, defaul 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_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+
+ // Reset the received frame, frame count and timing info
+ memset(rx,0x00,sizeof(rx));
+ frame_count = 0;
+ response = 0;
+ overflow = 0;
+
+ while(!BUTTON_PRESS()) {
+ // Watchdog hit
+ WDT_HIT();
+
+ // Receive frame, watch for at most T0*EOF periods
+ while (AT91C_BASE_TC1->TC_CV < 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/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++;
+ if (!bQuiet) {
+ if (!LogTrace(rx,nbytes(rxlen),response,0,true)) {
+ DbpString("Trace full");
+ if (bQuitTraceFull) {
+ break;
+ } else {
+ bQuiet = 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 < T0*(HITAG_T_WAIT_1-HITAG_T_LOW));
+
+ // Send and store the tag answer (if there is any)
+ if (txlen) {
+ // Transmit the tag frame
+ hitag_send_frame(tx,txlen);
+ // Store the frame in the trace
+ if (!bQuiet) {
+ if (!LogTrace(tx,nbytes(txlen),0,0,false)) {
+ DbpString("Trace full");
+ if (bQuitTraceFull) {
+ break;
+ } else {
+ bQuiet = true;
+ }
+ }
+ }
+ }
+
+ // 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/T0);
+ // Reset the timer to restart while-loop that receives frames
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
+ }
+ LED_B_OFF();
+ LED_D_OFF();
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+// Dbprintf("frame received: %d",frame_count);
+// Dbprintf("Authentication Attempts: %d",(auth_table_len/8));
+// DbpString("All done");
+}
+
+void ReaderHitag(hitag_function htf, hitag_data* htd) {
+ int frame_count;
+ int response;
+ byte_t rx[HITAG_FRAME_LEN];
+ size_t rxlen=0;
+ byte_t txbuf[HITAG_FRAME_LEN];
+ byte_t* tx = txbuf;
+ size_t txlen=0;
+ int lastbit;
+ bool bSkip;
+ int reset_sof;
+ int tag_sof;
+ int t_wait = HITAG_T_WAIT_MAX;
+ bool bStop;
+ bool bQuitTraceFull = false;
+
+ // Clean up trace and prepare it for storing frames
+ iso14a_set_tracing(TRUE);
+ iso14a_clear_trace();
+ DbpString("Starting Hitag reader family");
+
+ // Check configuration
+ switch(htf) {
+ case RHT2F_PASSWORD: {
+ Dbprintf("List identifier in password mode");
+ memcpy(password,htd->pwd.password,4);
+ bQuitTraceFull = false;
+ bQuiet = false;
+ bPwd = false;
+ } break;
+ case RHT2F_AUTHENTICATE: {
+ DbpString("Authenticating in crypto mode");
+ memcpy(NrAr,htd->auth.NrAr,8);
+ Dbprintf("Reader-challenge:");
+ Dbhexdump(8,NrAr,false);
+ bQuiet = false;
+ bCrypto = false;
+ bQuitTraceFull = true;
+ } break;
+
+ case RHT2F_TEST_AUTH_ATTEMPTS: {
+ Dbprintf("Testing %d authentication attempts",(auth_table_len/8));
+ auth_table_pos = 0;
+ memcpy(NrAr,auth_table,8);
+ bQuitTraceFull = false;
+ bQuiet = false;
+ bCrypto = false;
+ } break;
+
+ default: {
+ Dbprintf("Error, unknown function: %d",htf);
+ return;
+ } break;
+ }
+
+ LED_D_ON();
+ hitag2_init();
+
+ // Configure output and enable 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;
+
+ // Set fpga in edge detect with reader field, we can modulate as reader now
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
+
+ // Set Frequency divisor which will drive the FPGA and analog mux selection
+ FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+ SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+ RELAY_OFF();
+
+ // Disable modulation at default, which means enable the field
+ LOW(GPIO_SSC_DOUT);
+
+ // Give it a bit of time for the resonant antenna to settle.
+ SpinDelay(30);
+
+ // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
+ AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
+
+ // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the tag 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, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
+ // external trigger rising edge, load RA on falling edge of TIOA.
+ AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_FALLING | AT91C_TC_ABETRG | AT91C_TC_LDRA_FALLING;
+
+ // Enable and reset counters
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+
+ // Reset the received frame, frame count and timing info
+ frame_count = 0;
+ response = 0;
+ lastbit = 1;
+ bStop = false;
+
+ // Tag specific configuration settings (sof, timings, etc.)
+ if (htf < 10){
+ // hitagS settings
+ reset_sof = 1;
+ t_wait = 200;
+ DbpString("Configured for hitagS reader");
+ } else if (htf < 20) {
+ // hitag1 settings
+ reset_sof = 1;
+ t_wait = 200;
+ DbpString("Configured for hitag1 reader");
+ } else if (htf < 30) {
+ // hitag2 settings
+ reset_sof = 4;
+ t_wait = HITAG_T_WAIT_2;
+ DbpString("Configured for hitag2 reader");
+ } else {
+ Dbprintf("Error, unknown hitag reader type: %d",htf);
+ return;
+ }
+
+ while(!bStop && !BUTTON_PRESS()) {
+ // Watchdog hit
+ WDT_HIT();
+
+ // Check if frame was captured and store it
+ if(rxlen > 0) {
+ frame_count++;
+ if (!bQuiet) {
+ if (!LogTrace(rx,nbytes(rxlen),response,0,false)) {
+ DbpString("Trace full");
+ if (bQuitTraceFull) {
+ break;
+ } else {
+ bQuiet = true;
+ }
+ }
+ }
+ }
+
+ // By default reset the transmission buffer
+ tx = txbuf;
+ switch(htf) {
+ case RHT2F_PASSWORD: {
+ bStop = !hitag2_password(rx,rxlen,tx,&txlen);
+ } break;
+ case RHT2F_AUTHENTICATE: {
+ bStop = !hitag2_authenticate(rx,rxlen,tx,&txlen);
+ } break;
+ case RHT2F_TEST_AUTH_ATTEMPTS: {
+ bStop = !hitag2_test_auth_attempts(rx,rxlen,tx,&txlen);
+ } break;
+ default: {
+ Dbprintf("Error, unknown function: %d",htf);
+ return;
+ } break;
+ }
+
+ // Send and store the reader command
+ // Disable timer 1 with external trigger to avoid triggers during our own modulation
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+
+ // Wait for HITAG_T_WAIT_2 carrier periods after the last tag bit before transmitting,
+ // Since the clock counts since the last falling edge, a 'one' means that the
+ // falling edge occured halfway the period. with respect to this falling edge,
+ // we need to wait (T_Wait2 + half_tag_period) when the last was a 'one'.
+ // All timer values are in terms of T0 units
+ while(AT91C_BASE_TC0->TC_CV < T0*(t_wait+(HITAG_T_TAG_HALF_PERIOD*lastbit)));
+
+ // Transmit the reader frame
+ hitag_reader_send_frame(tx,txlen);
+
+ // Enable and reset external trigger in timer for capturing future frames
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+
+ // Add transmitted frame to total count
+ if(txlen > 0) {
+ frame_count++;
+ if (!bQuiet) {
+ // Store the frame in the trace
+ if (!LogTrace(tx,nbytes(txlen),HITAG_T_WAIT_2,0,true)) {
+ if (bQuitTraceFull) {
+ break;
+ } else {
+ bQuiet = true;
+ }
+ }
+ }
+ }
+
+ // Reset values for receiving frames
+ memset(rx,0x00,sizeof(rx));
+ rxlen = 0;
+ lastbit = 1;
+ bSkip = true;
+ tag_sof = reset_sof;
+ response = 0;
+
+ // Receive frame, watch for at most T0*EOF periods
+ while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_WAIT_MAX) {
+ // Check if falling edge in tag modulation is detected
+ if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
+ // Retrieve the new timing values
+ int ra = (AT91C_BASE_TC1->TC_RA/T0);
+
+ // Reset timer every frame, we have to capture the last edge for timing
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
+
+ LED_B_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 recieve 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) {
+ 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++;
+ }
+ } else {
+ // Ignore wierd value, is to small to mean anything
+ }
+ }
+
+ // We can break this loop if we received the last bit from a frame
+ if (AT91C_BASE_TC1->TC_CV > T0*HITAG_T_EOF) {
+ if (rxlen>0) break;
+ }
+ }
+ }
+ LED_B_OFF();
+ LED_D_OFF();
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+ AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+
+// Dbprintf("frame received: %d",frame_count);
+// DbpString("All done");
+}
projects / proxmark3-svn / commitdiff