//-----------------------------------------------------------------------------
// (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
// 2016 Iceman
-// 2018 AntiCat (rwd rewritten)
+// 2018 AntiCat
//
// 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
#include "legic.h"
#include "crc.h"
-static struct legic_frame {
- int bits;
- uint32_t data;
-} current_frame;
-
-static enum {
- STATE_DISCON,
- STATE_IV,
- STATE_CON,
-} legic_state;
-
-static crc_t legic_crc;
-static int legic_read_count;
-static uint32_t legic_prng_bc;
-static uint32_t legic_prng_iv;
-
-static int legic_phase_drift;
-static int legic_frame_drift;
-static int legic_reqresp_drift;
-
-AT91PS_TC timer;
-AT91PS_TC prng_timer;
-
static legic_card_select_t card;/* metadata of currently selected card */
+static crc_t legic_crc;
//-----------------------------------------------------------------------------
// Frame timing and pseudorandom number generator
#define TAG_BIT_PERIOD 150 /* 100us */
#define TAG_WRITE_TIMEOUT 60 /* 40 * 100us (write should take at most 3.6ms) */
-#define SIM_DIVISOR 586 /* prng_time/DIV count prng needs to be forwared */
-#define SIM_SHIFT 900 /* prng_time+SHIFT shift of delayed start */
-#define RWD_TIME_FUZZ 20 /* rather generous 13us, since the peak detector
- /+ hysteresis fuzz quite a bit */
-
#define LEGIC_READ 0x01 /* Read Command */
#define LEGIC_WRITE 0x00 /* Write Command */
#define INPUT_THRESHOLD 8 /* heuristically determined, lower values */
/* lead to detecting false ack during write */
-#define FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz)))
-
//-----------------------------------------------------------------------------
// I/O interface abstraction (FPGA -> ARM)
//-----------------------------------------------------------------------------
-static inline uint8_t rx_byte_from_fpga() {
+static inline uint16_t rx_frame_from_fpga() {
for(;;) {
WDT_HIT();
- // wait for byte be become available in rx holding register
+ // wait for frame be become available in rx holding register
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
return AT91C_BASE_SSC->SSC_RHR;
}
// To reduce CPU time the amplitude is approximated by using linear functions:
// am = MAX(ABS(i),ABS(q)) + 1/2*MIN(ABS(i),ABSq))
//
-// Note: The SSC receiver is never synchronized the calculation my be performed
-// on a I/Q pair from two subsequent correlations, but does not matter.
-//
// The bit time is 99.1us (21 I/Q pairs). The receiver skips the first 5 samples
// and averages the next (most stable) 8 samples. The final 8 samples are dropped
// also.
//
-// The demedulated should be alligned to the bit periode by the caller. This is
-// done in rx_bit_as_reader and rx_ack_as_reader.
-static inline bool rx_bit_as_reader() {
- int32_t cq = 0;
- int32_t ci = 0;
+// The demodulated should be alligned to the bit period by the caller. This is
+// done in rx_bit and rx_ack.
+static inline bool rx_bit() {
+ int32_t sum_cq = 0;
+ int32_t sum_ci = 0;
// skip first 5 I/Q pairs
for(size_t i = 0; i<5; ++i) {
- (int8_t)rx_byte_from_fpga();
- (int8_t)rx_byte_from_fpga();
+ (void)rx_frame_from_fpga();
}
// sample next 8 I/Q pairs
for(size_t i = 0; i<8; ++i) {
- cq += (int8_t)rx_byte_from_fpga();
- ci += (int8_t)rx_byte_from_fpga();
+ uint16_t iq = rx_frame_from_fpga();
+ int8_t ci = (int8_t)(iq >> 8);
+ int8_t cq = (int8_t)(iq & 0xff);
+ sum_ci += ci;
+ sum_cq += cq;
}
// calculate power
- int32_t power = (MAX(ABS(ci), ABS(cq)) + (MIN(ABS(ci), ABS(cq)) >> 1));
+ int32_t power = (MAX(ABS(sum_ci), ABS(sum_cq)) + MIN(ABS(sum_ci), ABS(sum_cq))/2);
// compare average (power / 8) to threshold
return ((power >> 3) > INPUT_THRESHOLD);
// be circumvented, but the adventage over bitbang would be little.
//-----------------------------------------------------------------------------
-static inline void tx_bit_as_reader(bool bit) {
+static inline void tx_bit(bool bit) {
// insert pause
- LOW(GPIO_SSC_DOUT);
+ HIGH(GPIO_SSC_DOUT);
last_frame_end += RWD_TIME_PAUSE;
while(GET_TICKS < last_frame_end) { };
- HIGH(GPIO_SSC_DOUT);
- // return to high, wait for bit periode to end
+ // return to carrier on, wait for bit periode to end
+ LOW(GPIO_SSC_DOUT);
last_frame_end += (bit ? RWD_TIME_1 : RWD_TIME_0) - RWD_TIME_PAUSE;
while(GET_TICKS < last_frame_end) { };
}
// present.
//-----------------------------------------------------------------------------
-static void tx_frame_as_reader(uint32_t frame, uint8_t len) {
+static void tx_frame(uint32_t frame, uint8_t len) {
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
// wait for next tx timeslot
// transmit frame, MSB first
for(uint8_t i = 0; i < len; ++i) {
bool bit = (frame >> i) & 0x01;
- tx_bit_as_reader(bit ^ legic_prng_get_bit());
+ tx_bit(bit ^ legic_prng_get_bit());
legic_prng_forward(1);
};
// add pause to mark end of the frame
- LOW(GPIO_SSC_DOUT);
+ HIGH(GPIO_SSC_DOUT);
last_frame_end += RWD_TIME_PAUSE;
while(GET_TICKS < last_frame_end) { };
- HIGH(GPIO_SSC_DOUT);
+ LOW(GPIO_SSC_DOUT);
}
-static uint32_t rx_frame_as_reader(uint8_t len) {
+static uint32_t rx_frame(uint8_t len) {
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR
| FPGA_HF_READER_RX_XCORR_848_KHZ
| FPGA_HF_READER_RX_XCORR_QUARTER_FREQ);
while(GET_TICKS < last_frame_end) { };
uint32_t frame = 0;
- for(uint8_t i = 0; i < len; i++) {
- frame |= (rx_bit_as_reader() ^ legic_prng_get_bit()) << i;
+ for(uint8_t i = 0; i < len; ++i) {
+ frame |= (rx_bit() ^ legic_prng_get_bit()) << i;
legic_prng_forward(1);
- // rx_bit_as_reader runs only 95us, resync to TAG_BIT_PERIOD
+ // rx_bit runs only 95us, resync to TAG_BIT_PERIOD
last_frame_end += TAG_BIT_PERIOD;
while(GET_TICKS < last_frame_end) { };
}
return frame;
}
-static bool rx_ack_as_reader() {
+static bool rx_ack() {
// change fpga into rx mode
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR
| FPGA_HF_READER_RX_XCORR_848_KHZ
uint32_t ack = 0;
for(uint8_t i = 0; i < TAG_WRITE_TIMEOUT; ++i) {
// sample bit
- ack = rx_bit_as_reader();
+ ack = rx_bit();
legic_prng_forward(1);
- // rx_bit_as_reader runs only 95us, resync to TAG_BIT_PERIOD
+ // rx_bit runs only 95us, resync to TAG_BIT_PERIOD
last_frame_end += TAG_BIT_PERIOD;
while(GET_TICKS < last_frame_end) { };
// Legic Reader
//-----------------------------------------------------------------------------
-int init_card(uint8_t cardtype, legic_card_select_t *p_card) {
+static int init_card(uint8_t cardtype, legic_card_select_t *p_card) {
p_card->tagtype = cardtype;
switch(p_card->tagtype) {
LED_D_ON();
// configure SSC with defaults
- FpgaSetupSsc();
+ FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
// re-claim GPIO_SSC_DOUT as GPIO and enable output
AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
- HIGH(GPIO_SSC_DOUT);
+ LOW(GPIO_SSC_DOUT);
// init crc calculator
crc_init(&legic_crc, 4, 0x19 >> 1, 0x05, 0);
// The setup consists of a three way handshake:
// - Transmit initialisation vector 7 bits
// - Receive card type 6 bits
-// - Acknowledge frame 6 bits
-static uint32_t setup_phase_reader(uint8_t iv) {
+// - Transmit Acknowledge 6 bits
+static uint32_t setup_phase(uint8_t iv) {
// init coordination timestamp
last_frame_end = GET_TICKS;
while(GET_TICKS < last_frame_end) { };
legic_prng_init(0);
- tx_frame_as_reader(iv, 7);
+ tx_frame(iv, 7);
- // configure iv
+ // configure prng
legic_prng_init(iv);
legic_prng_forward(2);
// receive card type
- int32_t card_type = rx_frame_as_reader(6);
+ int32_t card_type = rx_frame(6);
legic_prng_forward(3);
// send obsfuscated acknowledgment frame
switch (card_type) {
case 0x0D:
- tx_frame_as_reader(0x19, 6); // MIM22 | READCMD = 0x18 | 0x01
+ tx_frame(0x19, 6); // MIM22 | READCMD = 0x18 | 0x01
break;
case 0x1D:
case 0x3D:
- tx_frame_as_reader(0x39, 6); // MIM256 | READCMD = 0x38 | 0x01
+ tx_frame(0x39, 6); // MIM256 | READCMD = 0x38 | 0x01
break;
}
// read one byte
LED_B_ON();
legic_prng_forward(2);
- tx_frame_as_reader(cmd, cmd_sz);
+ tx_frame(cmd, cmd_sz);
legic_prng_forward(2);
- uint32_t frame = rx_frame_as_reader(12);
+ uint32_t frame = rx_frame(12);
LED_B_OFF();
// split frame into data and crc
// send write command
LED_C_ON();
legic_prng_forward(2);
- tx_frame_as_reader(cmd, addr_sz + 1 + 8 + 4); // sz = addr_sz + cmd + data + crc
+ tx_frame(cmd, addr_sz + 1 + 8 + 4); // sz = addr_sz + cmd + data + crc
legic_prng_forward(3);
LED_C_OFF();
// wait for ack
- return rx_ack_as_reader();
+ return rx_ack();
}
//-----------------------------------------------------------------------------
// establish shared secret and detect card type
DbpString("Reading card ...");
- uint8_t card_type = setup_phase_reader(SESSION_IV);
+ uint8_t card_type = setup_phase(SESSION_IV);
if(init_card(card_type, &card) != 0) {
Dbprintf("No or unknown card found, aborting");
goto OUT;
// establish shared secret and detect card type
Dbprintf("Writing 0x%02.2x - 0x%02.2x ...", offset, offset+bytes);
- uint8_t card_type = setup_phase_reader(SESSION_IV);
+ uint8_t card_type = setup_phase(SESSION_IV);
if(init_card(card_type, &card) != 0) {
Dbprintf("No or unknown card found, aborting");
goto OUT;
LED_D_OFF();
StopTicks();
}
-
-//-----------------------------------------------------------------------------
-// Legic Simulator
-//-----------------------------------------------------------------------------
-
-static void setup_timer(void)
-{
- /* Set up Timer 1 to use for measuring time between pulses. Since we're bit-banging
- * this it won't be terribly accurate but should be good enough.
- */
- AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
- timer = AT91C_BASE_TC1;
- timer->TC_CCR = AT91C_TC_CLKDIS;
- timer->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK;
- timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
-
- /*
- * Set up Timer 2 to use for measuring time between frames in
- * tag simulation mode. Runs 4x faster as Timer 1
- */
- AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC2);
- prng_timer = AT91C_BASE_TC2;
- prng_timer->TC_CCR = AT91C_TC_CLKDIS;
- prng_timer->TC_CMR = AT91C_TC_CLKS_TIMER_DIV2_CLOCK;
- prng_timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
-}
-
-/* Generate Keystream */
-static uint32_t get_key_stream(int skip, int count)
-{
- uint32_t key=0; int i;
-
- /* Use int to enlarge timer tc to 32bit */
- legic_prng_bc += prng_timer->TC_CV;
- prng_timer->TC_CCR = AT91C_TC_SWTRG;
-
- /* If skip == -1, forward prng time based */
- if(skip == -1) {
- i = (legic_prng_bc+SIM_SHIFT)/SIM_DIVISOR; /* Calculate Cycles based on timer */
- i -= legic_prng_count(); /* substract cycles of finished frames */
- i -= count; /* substract current frame length, rewidn to bedinning */
- legic_prng_forward(i);
- } else {
- legic_prng_forward(skip);
- }
-
- /* Write Time Data into LOG */
- uint8_t *BigBuf = BigBuf_get_addr();
- if(count == 6) { i = -1; } else { i = legic_read_count; }
- BigBuf[OFFSET_LOG+128+i] = legic_prng_count();
- BigBuf[OFFSET_LOG+256+i*4] = (legic_prng_bc >> 0) & 0xff;
- BigBuf[OFFSET_LOG+256+i*4+1] = (legic_prng_bc >> 8) & 0xff;
- BigBuf[OFFSET_LOG+256+i*4+2] = (legic_prng_bc >>16) & 0xff;
- BigBuf[OFFSET_LOG+256+i*4+3] = (legic_prng_bc >>24) & 0xff;
- BigBuf[OFFSET_LOG+384+i] = count;
-
- /* Generate KeyStream */
- for(i=0; i<count; i++) {
- key |= legic_prng_get_bit() << i;
- legic_prng_forward(1);
- }
- return key;
-}
-
-/* Send a frame in tag mode, the FPGA must have been set up by
- * LegicRfSimulate
- */
-static void frame_send_tag(uint16_t response, int bits, int crypt)
-{
- /* Bitbang the response */
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
- AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
-
- /* Use time to crypt frame */
- if(crypt) {
- legic_prng_forward(2); /* TAG_TIME_WAIT -> shift by 2 */
- int i; int key = 0;
- for(i=0; i<bits; i++) {
- key |= legic_prng_get_bit() << i;
- legic_prng_forward(1);
- }
- //Dbprintf("key = 0x%x", key);
- response = response ^ key;
- }
-
- /* Wait for the frame start */
- while(timer->TC_CV < (TAG_FRAME_WAIT - 30)) ;
-
- int i;
- for(i=0; i<bits; i++) {
- int nextbit = timer->TC_CV + TAG_BIT_PERIOD;
- int bit = response & 1;
- response = response >> 1;
- if(bit) {
- AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
- } else {
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- }
- while(timer->TC_CV < nextbit) ;
- }
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
-}
-
-static void frame_append_bit(struct legic_frame * const f, int bit)
-{
- if(f->bits >= 31) {
- return; /* Overflow, won't happen */
- }
- f->data |= (bit<<f->bits);
- f->bits++;
-}
-
-static void frame_clean(struct legic_frame * const f)
-{
- f->data = 0;
- f->bits = 0;
-}
-
-/* Handle (whether to respond) a frame in tag mode */
-static void frame_handle_tag(struct legic_frame const * const f)
-{
- uint8_t *BigBuf = BigBuf_get_addr();
-
- /* First Part of Handshake (IV) */
- if(f->bits == 7) {
- if(f->data == SESSION_IV) {
- LED_C_ON();
- prng_timer->TC_CCR = AT91C_TC_SWTRG;
- legic_prng_init(f->data);
- frame_send_tag(0x3d, 6, 1); /* 0x3d^0x26 = 0x1b */
- legic_state = STATE_IV;
- legic_read_count = 0;
- legic_prng_bc = 0;
- legic_prng_iv = f->data;
-
- /* TIMEOUT */
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1);
- while(timer->TC_CV < 280);
- return;
- } else if((prng_timer->TC_CV % 50) > 40) {
- legic_prng_init(f->data);
- frame_send_tag(0x3d, 6, 1);
- SpinDelay(20);
- return;
- }
- }
-
- /* 0x19==??? */
- if(legic_state == STATE_IV) {
- if((f->bits == 6) && (f->data == (0x19 ^ get_key_stream(1, 6)))) {
- legic_state = STATE_CON;
-
- /* TIMEOUT */
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1);
- while(timer->TC_CV < 200);
- return;
- } else {
- legic_state = STATE_DISCON;
- LED_C_OFF();
- Dbprintf("0x19 - Frame: %03.3x", f->data);
- return;
- }
- }
-
- /* Read */
- if(f->bits == 11) {
- if(legic_state == STATE_CON) {
- int key = get_key_stream(-1, 11); //legic_phase_drift, 11);
- int addr = f->data ^ key; addr = addr >> 1;
- int data = BigBuf[addr];
- int hash = calc_crc4(addr, data, 11) << 8;
- BigBuf[OFFSET_LOG+legic_read_count] = (uint8_t)addr;
- legic_read_count++;
-
- //Dbprintf("Data:%03.3x, key:%03.3x, addr: %03.3x, read_c:%u", f->data, key, addr, read_c);
- legic_prng_forward(legic_reqresp_drift);
-
- frame_send_tag(hash | data, 12, 1);
-
- /* SHORT TIMEOUT */
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1);
- legic_prng_forward(legic_frame_drift);
- while(timer->TC_CV < 180);
- return;
- }
- }
-
- /* Write */
- if(f->bits == 23) {
- int key = get_key_stream(-1, 23); //legic_frame_drift, 23);
- int addr = f->data ^ key; addr = addr >> 1; addr = addr & 0x3ff;
- int data = f->data ^ key; data = data >> 11; data = data & 0xff;
-
- /* write command */
- legic_state = STATE_DISCON;
- LED_C_OFF();
- Dbprintf("write - addr: %x, data: %x", addr, data);
- return;
- }
-
- if(legic_state != STATE_DISCON) {
- Dbprintf("Unexpected: sz:%u, Data:%03.3x, State:%u, Count:%u", f->bits, f->data, legic_state, legic_read_count);
- int i;
- Dbprintf("IV: %03.3x", legic_prng_iv);
- for(i = 0; i<legic_read_count; i++) {
- Dbprintf("Read Nb: %u, Addr: %u", i, BigBuf[OFFSET_LOG+i]);
- }
-
- for(i = -1; i<legic_read_count; i++) {
- uint32_t t;
- t = BigBuf[OFFSET_LOG+256+i*4];
- t |= BigBuf[OFFSET_LOG+256+i*4+1] << 8;
- t |= BigBuf[OFFSET_LOG+256+i*4+2] <<16;
- t |= BigBuf[OFFSET_LOG+256+i*4+3] <<24;
-
- Dbprintf("Cycles: %u, Frame Length: %u, Time: %u",
- BigBuf[OFFSET_LOG+128+i],
- BigBuf[OFFSET_LOG+384+i],
- t);
- }
- }
- legic_state = STATE_DISCON;
- legic_read_count = 0;
- SpinDelay(10);
- LED_C_OFF();
- return;
-}
-
-/* Read bit by bit untill full frame is received
- * Call to process frame end answer
- */
-static void emit(int bit)
-{
- if(bit == -1) {
- if(current_frame.bits <= 4) {
- frame_clean(¤t_frame);
- } else {
- frame_handle_tag(¤t_frame);
- frame_clean(¤t_frame);
- }
- WDT_HIT();
- } else if(bit == 0) {
- frame_append_bit(¤t_frame, 0);
- } else if(bit == 1) {
- frame_append_bit(¤t_frame, 1);
- }
-}
-
-void LegicRfSimulate(int phase, int frame, int reqresp)
-{
- /* ADC path high-frequency peak detector, FPGA in high-frequency simulator mode,
- * modulation mode set to 212kHz subcarrier. We are getting the incoming raw
- * envelope waveform on DIN and should send our response on DOUT.
- *
- * The LEGIC RF protocol is pulse-pause-encoding from reader to card, so we'll
- * measure the time between two rising edges on DIN, and no encoding on the
- * subcarrier from card to reader, so we'll just shift out our verbatim data
- * on DOUT, 1 bit is 100us. The time from reader to card frame is still unclear,
- * seems to be 300us-ish.
- */
-
- if(phase < 0) {
- int i;
- for(i=0; i<=reqresp; i++) {
- legic_prng_init(SESSION_IV);
- Dbprintf("i=%u, key 0x%3.3x", i, get_key_stream(i, frame));
- }
- return;
- }
-
- legic_phase_drift = phase;
- legic_frame_drift = frame;
- legic_reqresp_drift = reqresp;
-
- FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
- SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
- FpgaSetupSsc();
- FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_212K);
-
- /* Bitbang the receiver */
- AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
- AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
-
- setup_timer();
- crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0);
-
- int old_level = 0;
- int active = 0;
- legic_state = STATE_DISCON;
-
- LED_B_ON();
- DbpString("Starting Legic emulator, press button to end");
- while(!BUTTON_PRESS()) {
- int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
- int time = timer->TC_CV;
-
- if(level != old_level) {
- if(level == 1) {
- timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
- if(FUZZ_EQUAL(time, RWD_TIME_1, RWD_TIME_FUZZ)) {
- /* 1 bit */
- emit(1);
- active = 1;
- LED_A_ON();
- } else if(FUZZ_EQUAL(time, RWD_TIME_0, RWD_TIME_FUZZ)) {
- /* 0 bit */
- emit(0);
- active = 1;
- LED_A_ON();
- } else if(active) {
- /* invalid */
- emit(-1);
- active = 0;
- LED_A_OFF();
- }
- }
- }
-
- if(time >= (RWD_TIME_1+RWD_TIME_FUZZ) && active) {
- /* Frame end */
- emit(-1);
- active = 0;
- LED_A_OFF();
- }
-
- if(time >= (20*RWD_TIME_1) && (timer->TC_SR & AT91C_TC_CLKSTA)) {
- timer->TC_CCR = AT91C_TC_CLKDIS;
- }
-
- old_level = level;
- WDT_HIT();
- }
- DbpString("Stopped");
- LED_B_OFF();
- LED_A_OFF();
- LED_C_OFF();
-}
-
projects / proxmark3-svn / blobdiff