//-----------------------------------------------------------------------------
// (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
+// 2016 Iceman
+// 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
// LEGIC RF simulation code
//-----------------------------------------------------------------------------
+#include "legicrf.h"
+
#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "string.h"
-
-#include "legicrf.h"
#include "legic_prng.h"
+#include "legic.h"
#include "crc.h"
+#include "fpgaloader.h"
+
+static legic_card_select_t card;/* metadata of currently selected card */
+static crc_t legic_crc;
+
+//-----------------------------------------------------------------------------
+// Frame timing and pseudorandom number generator
+//
+// The Prng is forwarded every 100us (TAG_BIT_PERIOD), except when the reader is
+// transmitting. In that case the prng has to be forwarded every bit transmitted:
+// - 60us for a 0 (RWD_TIME_0)
+// - 100us for a 1 (RWD_TIME_1)
+//
+// The data dependent timing makes writing comprehensible code significantly
+// harder. The current aproach forwards the prng data based if there is data on
+// air and time based, using GET_TICKS, during computational and wait periodes.
+//
+// To not have the necessity to calculate/guess exection time dependend timeouts
+// tx_frame and rx_frame use a shared timestamp to coordinate tx and rx timeslots.
+//-----------------------------------------------------------------------------
+
+static uint32_t last_frame_end; /* ts of last bit of previews rx or tx frame */
-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 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;
+#define RWD_TIME_PAUSE 30 /* 20us */
+#define RWD_TIME_1 150 /* READER_TIME_PAUSE 20us off + 80us on = 100us */
+#define RWD_TIME_0 90 /* READER_TIME_PAUSE 20us off + 40us on = 60us */
+#define RWD_FRAME_WAIT 330 /* 220us from TAG frame end to READER frame start */
+#define TAG_FRAME_WAIT 495 /* 330us from READER frame end to TAG frame start */
+#define TAG_BIT_PERIOD 150 /* 100us */
+#define TAG_WRITE_TIMEOUT 60 /* 40 * 100us (write should take at most 3.6ms) */
+
+#define LEGIC_READ 0x01 /* Read Command */
+#define LEGIC_WRITE 0x00 /* Write Command */
+
+#define SESSION_IV 0x55 /* An arbitrary chose session IV, all shoud work */
+#define OFFSET_LOG 1024 /* The largest Legic Prime card is 1k */
+#define WRITE_LOWERLIMIT 4 /* UID and MCC are not writable */
+
+#define INPUT_THRESHOLD 8 /* heuristically determined, lower values */
+ /* lead to detecting false ack during write */
+
+//-----------------------------------------------------------------------------
+// I/O interface abstraction (FPGA -> ARM)
+//-----------------------------------------------------------------------------
+
+static inline uint16_t rx_frame_from_fpga() {
+ for(;;) {
+ WDT_HIT();
+
+ // 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;
+ }
+ }
}
-/* At TIMER_CLOCK3 (MCK/32) */
-#define RWD_TIME_1 150 /* RWD_TIME_PAUSE off, 80us on = 100us */
-#define RWD_TIME_0 90 /* RWD_TIME_PAUSE off, 40us on = 60us */
-#define RWD_TIME_PAUSE 30 /* 20us */
-#define RWD_TIME_FUZZ 20 /* rather generous 13us, since the peak detector + hysteresis fuzz quite a bit */
-#define TAG_TIME_BIT 150 /* 100us for every bit */
-#define TAG_TIME_WAIT 490 /* time from RWD frame end to tag frame start, experimentally determined */
-
-#define SIM_DIVISOR 586 /* prng_time/SIM_DIVISOR count prng needs to be forwared */
-#define SIM_SHIFT 900 /* prng_time+SIM_SHIFT shift of delayed start */
-
-#define SESSION_IV 0x55
-#define OFFSET_LOG 1024
-
-#define FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz)))
-
-/* 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);
+//-----------------------------------------------------------------------------
+// Demodulation (Reader)
+//-----------------------------------------------------------------------------
+
+// Returns a demedulated bit
+//
+// The FPGA running xcorrelation samples the subcarrier at ~13.56 MHz. The mode
+// was initialy designed to receive BSPK/2-PSK. Hance, it reports an I/Q pair
+// every 4.7us (8 bits i and 8 bits q).
+//
+// The subcarrier amplitude can be calculated using Pythagoras sqrt(i^2 + q^2).
+// To reduce CPU time the amplitude is approximated by using linear functions:
+// am = MAX(ABS(i),ABS(q)) + 1/2*MIN(ABS(i),ABSq))
+//
+// 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 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) {
+ (void)rx_frame_from_fpga();
}
- /* Write Time Data into LOG */
- if(count == 6) { i = -1; } else { i = legic_read_count; }
- ((uint8_t*)BigBuf)[OFFSET_LOG+128+i] = legic_prng_count();
- ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4] = (legic_prng_bc >> 0) & 0xff;
- ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4+1] = (legic_prng_bc >> 8) & 0xff;
- ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4+2] = (legic_prng_bc >>16) & 0xff;
- ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4+3] = (legic_prng_bc >>24) & 0xff;
- ((uint8_t*)BigBuf)[OFFSET_LOG+384+i] = count;
-
- /* Generate KeyStream */
- for(i=0; i<count; i++) {
- key |= legic_prng_get_bit() << i;
- legic_prng_forward(1);
+ // sample next 8 I/Q pairs
+ for(size_t i = 0; i<8; ++i) {
+ 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;
}
- 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_TIME_WAIT - 30)) ;
-
- int i;
- for(i=0; i<bits; i++) {
- int nextbit = timer->TC_CV + TAG_TIME_BIT;
- 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;
-}
+ // calculate power
+ int32_t power = (MAX(ABS(sum_ci), ABS(sum_cq)) + MIN(ABS(sum_ci), ABS(sum_cq))/2);
-/* Send a frame in reader mode, the FPGA must have been set up by
- * LegicRfReader
- */
-static void frame_send_rwd(uint32_t data, int bits)
-{
- /* Start clock */
- timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
- while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
-
- int i;
- for(i=0; i<bits; i++) {
- int starttime = timer->TC_CV;
- int pause_end = starttime + RWD_TIME_PAUSE, bit_end;
- int bit = data & 1;
- data = data >> 1;
-
- if(bit ^ legic_prng_get_bit()) {
- bit_end = starttime + RWD_TIME_1;
- } else {
- bit_end = starttime + RWD_TIME_0;
- }
-
- /* RWD_TIME_PAUSE time off, then some time on, so that the complete bit time is
- * RWD_TIME_x, where x is the bit to be transmitted */
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- while(timer->TC_CV < pause_end) ;
- AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
- legic_prng_forward(1); /* bit duration is longest. use this time to forward the lfsr */
-
- while(timer->TC_CV < bit_end) ;
- }
-
- {
- /* One final pause to mark the end of the frame */
- int pause_end = timer->TC_CV + RWD_TIME_PAUSE;
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- while(timer->TC_CV < pause_end) ;
- AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
- }
-
- /* Reset the timer, to measure time until the start of the tag frame */
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
+ // compare average (power / 8) to threshold
+ return ((power >> 3) > INPUT_THRESHOLD);
}
-/* Receive a frame from the card in reader emulation mode, the FPGA and
- * timer must have been set up by LegicRfReader and frame_send_rwd.
- *
- * The LEGIC RF protocol from card to reader does not include explicit
- * frame start/stop information or length information. The reader must
- * know beforehand how many bits it wants to receive. (Notably: a card
- * sending a stream of 0-bits is indistinguishable from no card present.)
- *
- * Receive methodology: There is a fancy correlator in hi_read_rx_xcorr, but
- * I'm not smart enough to use it. Instead I have patched hi_read_tx to output
- * the ADC signal with hysteresis on SSP_DIN. Bit-bang that signal and look
- * for edges. Count the edges in each bit interval. If they are approximately
- * 0 this was a 0-bit, if they are approximately equal to the number of edges
- * expected for a 212kHz subcarrier, this was a 1-bit. For timing we use the
- * timer that's still running from frame_send_rwd in order to get a synchronization
- * with the frame that we just sent.
- *
- * FIXME: Because we're relying on the hysteresis to just do the right thing
- * the range is severely reduced (and you'll probably also need a good antenna).
- * So this should be fixed some time in the future for a proper receiver.
- */
-static void frame_receive_rwd(struct legic_frame * const f, int bits, int crypt)
-{
- uint32_t the_bit = 1; /* Use a bitmask to save on shifts */
- uint32_t data=0;
- int i, old_level=0, edges=0;
- int next_bit_at = TAG_TIME_WAIT;
-
- if(bits > 32) {
- bits = 32;
- }
+//-----------------------------------------------------------------------------
+// Modulation (Reader)
+//
+// I've tried to modulate the Legic specific pause-puls using ssc and the default
+// ssc clock of 105.4 kHz (bit periode of 9.4us) - previous commit. However,
+// the timing was not precise enough. By increasing the ssc clock this could
+// be circumvented, but the adventage over bitbang would be little.
+//-----------------------------------------------------------------------------
- AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
- AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
-
- /* we have some time now, precompute the cipher
- * since we cannot compute it on the fly while reading */
- legic_prng_forward(2);
-
- if(crypt)
- {
- for(i=0; i<bits; i++) {
- data |= legic_prng_get_bit() << i;
- legic_prng_forward(1);
- }
- }
-
- while(timer->TC_CV < next_bit_at) ;
-
- next_bit_at += TAG_TIME_BIT;
-
- for(i=0; i<bits; i++) {
- edges = 0;
- while(timer->TC_CV < next_bit_at) {
- int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
- if(level != old_level)
- edges++;
- old_level = level;
- }
- next_bit_at += TAG_TIME_BIT;
-
- if(edges > 20 && edges < 60) { /* expected are 42 edges */
- data ^= the_bit;
- }
- the_bit <<= 1;
- }
-
- f->data = data;
- f->bits = bits;
-
- /* Reset the timer, to synchronize the next frame */
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
-}
+static inline void tx_bit(bool bit) {
+ // insert pause
+ HIGH(GPIO_SSC_DOUT);
+ last_frame_end += RWD_TIME_PAUSE;
+ while(GET_TICKS < last_frame_end) { };
-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++;
+ // 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) { };
}
-static void frame_clean(struct legic_frame * const f)
-{
- f->data = 0;
- f->bits = 0;
+//-----------------------------------------------------------------------------
+// Frame Handling (Reader)
+//
+// The LEGIC RF protocol from card to reader does not include explicit frame
+// start/stop information or length information. The reader must know beforehand
+// how many bits it wants to receive.
+// Notably: a card sending a stream of 0-bits is indistinguishable from no card
+// present.
+//-----------------------------------------------------------------------------
+
+static void tx_frame(uint32_t frame, uint8_t len) {
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_FULL_MOD);
+
+ // wait for next tx timeslot
+ last_frame_end += RWD_FRAME_WAIT;
+ while(GET_TICKS < last_frame_end) { };
+
+ // transmit frame, MSB first
+ for(uint8_t i = 0; i < len; ++i) {
+ bool bit = (frame >> i) & 0x01;
+ tx_bit(bit ^ legic_prng_get_bit());
+ legic_prng_forward(1);
+ };
+
+ // add pause to mark end of the frame
+ HIGH(GPIO_SSC_DOUT);
+ last_frame_end += RWD_TIME_PAUSE;
+ while(GET_TICKS < last_frame_end) { };
+ LOW(GPIO_SSC_DOUT);
}
-static uint32_t perform_setup_phase_rwd(int iv)
-{
+static uint32_t rx_frame(uint8_t len) {
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_SUBCARRIER_212_KHZ | FPGA_HF_READER_MODE_RECEIVE_IQ);
- /* Switch on carrier and let the tag charge for 1ms */
- AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
- SpinDelay(1);
+ // hold sampling until card is expected to respond
+ last_frame_end += TAG_FRAME_WAIT;
+ while(GET_TICKS < last_frame_end) { };
- legic_prng_init(0); /* no keystream yet */
- frame_send_rwd(iv, 7);
- legic_prng_init(iv);
+ uint32_t frame = 0;
+ for(uint8_t i = 0; i < len; ++i) {
+ frame |= (rx_bit() ^ legic_prng_get_bit()) << i;
+ legic_prng_forward(1);
- frame_clean(¤t_frame);
- frame_receive_rwd(¤t_frame, 6, 1);
- legic_prng_forward(1); /* we wait anyways */
- while(timer->TC_CV < 387) ; /* ~ 258us */
- frame_send_rwd(0x19, 6);
+ // rx_bit runs only 95us, resync to TAG_BIT_PERIOD
+ last_frame_end += TAG_BIT_PERIOD;
+ while(GET_TICKS < last_frame_end) { };
+ }
- return current_frame.data;
+ return frame;
}
-static void LegicCommonInit(void) {
- FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
- SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
- FpgaSetupSsc();
- FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
+static bool rx_ack() {
+ // change fpga into rx mode
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_SUBCARRIER_212_KHZ | FPGA_HF_READER_MODE_RECEIVE_IQ);
- /* Bitbang the transmitter */
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
- AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
+ // hold sampling until card is expected to respond
+ last_frame_end += TAG_FRAME_WAIT;
+ while(GET_TICKS < last_frame_end) { };
- setup_timer();
+ uint32_t ack = 0;
+ for(uint8_t i = 0; i < TAG_WRITE_TIMEOUT; ++i) {
+ // sample bit
+ ack = rx_bit();
+ legic_prng_forward(1);
- crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0);
-}
+ // rx_bit runs only 95us, resync to TAG_BIT_PERIOD
+ last_frame_end += TAG_BIT_PERIOD;
+ while(GET_TICKS < last_frame_end) { };
-static void switch_off_tag_rwd(void)
-{
- /* Switch off carrier, make sure tag is reset */
- AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- SpinDelay(10);
+ // check if it was an ACK
+ if(ack) {
+ break;
+ }
+ }
- WDT_HIT();
-}
-/* calculate crc for a legic command */
-static int LegicCRC(int byte_index, int value, int cmd_sz) {
- crc_clear(&legic_crc);
- crc_update(&legic_crc, 1, 1); /* CMD_READ */
- crc_update(&legic_crc, byte_index, cmd_sz-1);
- crc_update(&legic_crc, value, 8);
- return crc_finish(&legic_crc);
+ return ack;
}
-int legic_read_byte(int byte_index, int cmd_sz) {
- int byte;
+//-----------------------------------------------------------------------------
+// Legic Reader
+//-----------------------------------------------------------------------------
+
+static int init_card(uint8_t cardtype, legic_card_select_t *p_card) {
+ p_card->tagtype = cardtype;
+
+ switch(p_card->tagtype) {
+ case 0x0d:
+ p_card->cmdsize = 6;
+ p_card->addrsize = 5;
+ p_card->cardsize = 22;
+ break;
+ case 0x1d:
+ p_card->cmdsize = 9;
+ p_card->addrsize = 8;
+ p_card->cardsize = 256;
+ break;
+ case 0x3d:
+ p_card->cmdsize = 11;
+ p_card->addrsize = 10;
+ p_card->cardsize = 1024;
+ break;
+ default:
+ p_card->cmdsize = 0;
+ p_card->addrsize = 0;
+ p_card->cardsize = 0;
+ return 2;
+ }
+ return 0;
+}
- legic_prng_forward(4); /* we wait anyways */
- while(timer->TC_CV < 387) ; /* ~ 258us + 100us*delay */
+static void init_reader(bool clear_mem) {
+ // configure FPGA
+ FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_SUBCARRIER_212_KHZ | FPGA_HF_READER_MODE_RECEIVE_IQ);
+ SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+ LED_D_ON();
- frame_send_rwd(1 | (byte_index << 1), cmd_sz);
- frame_clean(¤t_frame);
+ // configure SSC with defaults
+ FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
- frame_receive_rwd(¤t_frame, 12, 1);
+ // 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;
+ LOW(GPIO_SSC_DOUT);
- byte = current_frame.data & 0xff;
- if( LegicCRC(byte_index, byte, cmd_sz) != (current_frame.data >> 8) ) {
- Dbprintf("!!! crc mismatch: expected %x but got %x !!!",
- LegicCRC(byte_index, current_frame.data & 0xff, cmd_sz), current_frame.data >> 8);
- return -1;
- }
+ // init crc calculator
+ crc_init(&legic_crc, 4, 0x19 >> 1, 0x05, 0);
- return byte;
+ // start us timer
+ StartTicks();
}
-/* legic_write_byte() is not included, however it's trivial to implement
- * and here are some hints on what remains to be done:
- *
- * * assemble a write_cmd_frame with crc and send it
- * * wait until the tag sends back an ACK ('1' bit unencrypted)
- * * forward the prng based on the timing
- */
-int legic_write_byte(int byte, int addr, int addr_sz) {
- //do not write UID, CRC, DCF
- if(addr <= 0x06) {
- return 0;
- }
-
- //== send write command ==============================
- crc_clear(&legic_crc);
- crc_update(&legic_crc, 0, 1); /* CMD_WRITE */
- crc_update(&legic_crc, addr, addr_sz);
- crc_update(&legic_crc, byte, 8);
-
- uint32_t crc = crc_finish(&legic_crc);
- uint32_t cmd = ((crc <<(addr_sz+1+8)) //CRC
- |(byte <<(addr_sz+1)) //Data
- |(addr <<1) //Address
- |(0x00 <<0)); //CMD = W
- uint32_t cmd_sz = addr_sz+1+8+4; //crc+data+cmd
-
- legic_prng_forward(2); /* we wait anyways */
- while(timer->TC_CV < 387) ; /* ~ 258us */
- frame_send_rwd(cmd, cmd_sz);
-
- //== wait for ack ====================================
- int t, old_level=0, edges=0;
- int next_bit_at =0;
- while(timer->TC_CV < 387) ; /* ~ 258us */
- for(t=0; t<80; t++) {
- edges = 0;
- next_bit_at += TAG_TIME_BIT;
- while(timer->TC_CV < next_bit_at) {
- int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
- if(level != old_level) {
- edges++;
- }
- old_level = level;
- }
- if(edges > 20 && edges < 60) { /* expected are 42 edges */
- int t = timer->TC_CV;
- int c = t/TAG_TIME_BIT;
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
- legic_prng_forward(c);
- return 0;
- }
- }
- timer->TC_CCR = AT91C_TC_SWTRG;
- while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
- return -1;
+// Setup reader to card connection
+//
+// The setup consists of a three way handshake:
+// - Transmit initialisation vector 7 bits
+// - Receive card type 6 bits
+// - Transmit Acknowledge 6 bits
+static uint32_t setup_phase(uint8_t iv) {
+ // init coordination timestamp
+ last_frame_end = GET_TICKS;
+
+ // Switch on carrier and let the card charge for 5ms.
+ last_frame_end += 7500;
+ while(GET_TICKS < last_frame_end) { };
+
+ legic_prng_init(0);
+ tx_frame(iv, 7);
+
+ // configure prng
+ legic_prng_init(iv);
+ legic_prng_forward(2);
+
+ // receive card type
+ int32_t card_type = rx_frame(6);
+ legic_prng_forward(3);
+
+ // send obsfuscated acknowledgment frame
+ switch (card_type) {
+ case 0x0D:
+ tx_frame(0x19, 6); // MIM22 | READCMD = 0x18 | 0x01
+ break;
+ case 0x1D:
+ case 0x3D:
+ tx_frame(0x39, 6); // MIM256 | READCMD = 0x38 | 0x01
+ break;
+ }
+
+ return card_type;
}
-int LegicRfReader(int offset, int bytes) {
- int byte_index=0, cmd_sz=0, card_sz=0;
-
- LegicCommonInit();
-
- memset(BigBuf, 0, 1024);
-
- DbpString("setting up legic card");
- uint32_t tag_type = perform_setup_phase_rwd(SESSION_IV);
- switch_off_tag_rwd(); //we lose to mutch time with dprintf
- switch(tag_type) {
- case 0x1d:
- DbpString("MIM 256 card found, reading card ...");
- cmd_sz = 9;
- card_sz = 256;
- break;
- case 0x3d:
- DbpString("MIM 1024 card found, reading card ...");
- cmd_sz = 11;
- card_sz = 1024;
- break;
- default:
- Dbprintf("Unknown card format: %x",tag_type);
- return -1;
- }
- if(bytes == -1) {
- bytes = card_sz;
- }
- if(bytes+offset >= card_sz) {
- bytes = card_sz-offset;
- }
-
- perform_setup_phase_rwd(SESSION_IV);
-
- LED_B_ON();
- while(byte_index < bytes) {
- int r = legic_read_byte(byte_index+offset, cmd_sz);
- if(r == -1 ||BUTTON_PRESS()) {
- DbpString("operation aborted");
- switch_off_tag_rwd();
- LED_B_OFF();
- LED_C_OFF();
- return -1;
- }
- ((uint8_t*)BigBuf)[byte_index] = r;
- WDT_HIT();
- byte_index++;
- if(byte_index & 0x10) LED_C_ON(); else LED_C_OFF();
- }
- LED_B_OFF();
- LED_C_OFF();
- switch_off_tag_rwd();
- Dbprintf("Card read, use 'hf legic decode' or");
- Dbprintf("'data hexsamples %d' to view results", (bytes+7) & ~7);
- return 0;
+static uint8_t calc_crc4(uint16_t cmd, uint8_t cmd_sz, uint8_t value) {
+ crc_clear(&legic_crc);
+ crc_update(&legic_crc, (value << cmd_sz) | cmd, 8 + cmd_sz);
+ return crc_finish(&legic_crc);
}
-void LegicRfWriter(int bytes, int offset) {
- int byte_index=0, addr_sz=0;
-
- LegicCommonInit();
-
- DbpString("setting up legic card");
- uint32_t tag_type = perform_setup_phase_rwd(SESSION_IV);
- switch_off_tag_rwd();
- switch(tag_type) {
- case 0x1d:
- if(offset+bytes > 0x100) {
- Dbprintf("Error: can not write to 0x%03.3x on MIM 256", offset+bytes);
- return;
- }
- addr_sz = 8;
- Dbprintf("MIM 256 card found, writing 0x%02.2x - 0x%02.2x ...", offset, offset+bytes);
- break;
- case 0x3d:
- if(offset+bytes > 0x400) {
- Dbprintf("Error: can not write to 0x%03.3x on MIM 1024", offset+bytes);
- return;
- }
- addr_sz = 10;
- Dbprintf("MIM 1024 card found, writing 0x%03.3x - 0x%03.3x ...", offset, offset+bytes);
- break;
- default:
- Dbprintf("No or unknown card found, aborting");
- return;
- }
-
- LED_B_ON();
- perform_setup_phase_rwd(SESSION_IV);
- legic_prng_forward(2);
- while(byte_index < bytes) {
- int r = legic_write_byte(((uint8_t*)BigBuf)[byte_index+offset], byte_index+offset, addr_sz);
- if((r != 0) || BUTTON_PRESS()) {
- Dbprintf("operation aborted @ 0x%03.3x", byte_index);
- switch_off_tag_rwd();
- LED_B_OFF();
- LED_C_OFF();
- return;
- }
- WDT_HIT();
- byte_index++;
- if(byte_index & 0x10) LED_C_ON(); else LED_C_OFF();
- }
- LED_B_OFF();
- LED_C_OFF();
- DbpString("write successful");
+static int16_t read_byte(uint16_t index, uint8_t cmd_sz) {
+ uint16_t cmd = (index << 1) | LEGIC_READ;
+
+ // read one byte
+ LED_B_ON();
+ legic_prng_forward(2);
+ tx_frame(cmd, cmd_sz);
+ legic_prng_forward(2);
+ uint32_t frame = rx_frame(12);
+ LED_B_OFF();
+
+ // split frame into data and crc
+ uint8_t byte = BYTEx(frame, 0);
+ uint8_t crc = BYTEx(frame, 1);
+
+ // check received against calculated crc
+ uint8_t calc_crc = calc_crc4(cmd, cmd_sz, byte);
+ if(calc_crc != crc) {
+ Dbprintf("!!! crc mismatch: %x != %x !!!", calc_crc, crc);
+ return -1;
+ }
+
+ legic_prng_forward(1);
+
+ return byte;
}
-int timestamp;
-
-/* Handle (whether to respond) a frame in tag mode */
-static void frame_handle_tag(struct legic_frame const * const f)
-{
- /* 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 = ((uint8_t*)BigBuf)[addr];
- int hash = LegicCRC(addr, data, 11) << 8;
- ((uint8_t*)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, ((uint8_t*)BigBuf)[OFFSET_LOG+i]);
- }
-
- for(i = -1; i<legic_read_count; i++) {
- uint32_t t;
- t = ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4];
- t |= ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4+1] << 8;
- t |= ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4+2] <<16;
- t |= ((uint8_t*)BigBuf)[OFFSET_LOG+256+i*4+3] <<24;
-
- Dbprintf("Cycles: %u, Frame Length: %u, Time: %u",
- ((uint8_t*)BigBuf)[OFFSET_LOG+128+i],
- ((uint8_t*)BigBuf)[OFFSET_LOG+384+i],
- t);
- }
- }
- legic_state = STATE_DISCON;
- legic_read_count = 0;
- SpinDelay(10);
- LED_C_OFF();
- return;
+// Transmit write command, wait until (3.6ms) the tag sends back an unencrypted
+// ACK ('1' bit) and forward the prng time based.
+bool write_byte(uint16_t index, uint8_t byte, uint8_t addr_sz) {
+ uint32_t cmd = index << 1 | LEGIC_WRITE; // prepare command
+ uint8_t crc = calc_crc4(cmd, addr_sz + 1, byte); // calculate crc
+ cmd |= byte << (addr_sz + 1); // append value
+ cmd |= (crc & 0xF) << (addr_sz + 1 + 8); // and crc
+
+ // send write command
+ LED_C_ON();
+ legic_prng_forward(2);
+ 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();
}
-/* 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);
+//-----------------------------------------------------------------------------
+// Command Line Interface
+//
+// Only this functions are public / called from appmain.c
+//-----------------------------------------------------------------------------
+void LegicRfReader(int offset, int bytes) {
+ uint8_t *BigBuf = BigBuf_get_addr();
+ memset(BigBuf, 0, 1024);
+
+ // configure ARM and FPGA
+ init_reader(false);
+
+ // establish shared secret and detect card type
+ DbpString("Reading card ...");
+ uint8_t card_type = setup_phase(SESSION_IV);
+ uint8_t result = 0;
+ if(init_card(card_type, &card) != 0) {
+ result = 1;
+ goto OUT;
+ }
+
+ // if no argument is specified create full dump
+ if(bytes == -1) {
+ bytes = card.cardsize;
}
-}
-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();
+ // do not read beyond card memory
+ if(bytes + offset > card.cardsize) {
+ bytes = card.cardsize - offset;
+ }
+
+ for(uint16_t i = 0; i < bytes; ++i) {
+ int16_t byte = read_byte(offset + i, card.cmdsize);
+ if(byte == -1) {
+ result = 2;
+ goto OUT;
+ }
+ BigBuf[i] = byte;
+ }
+
+OUT:
+ cmd_send(CMD_ACK, result, bytes, 0, &card, sizeof(card));
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+ LED_B_OFF();
+ LED_C_OFF();
+ LED_D_OFF();
+ StopTicks();
}
+void LegicRfWriter(int bytes, int offset) {
+ uint8_t *BigBuf = BigBuf_get_addr();
+
+ // configure ARM and FPGA
+ init_reader(false);
+
+ // uid is not writeable
+ if(offset <= WRITE_LOWERLIMIT) {
+ 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(SESSION_IV);
+ if(init_card(card_type, &card) != 0) {
+ Dbprintf("No or unknown card found, aborting");
+ goto OUT;
+ }
+
+ // do not write beyond card memory
+ if(bytes + offset > card.cardsize) {
+ bytes = card.cardsize - offset;
+ }
+
+ // write in reverse order, only then is DCF (decremental field) writable
+ while(bytes-- > 0 && !BUTTON_PRESS()) {
+ if(!write_byte(bytes + offset, BigBuf[bytes + offset], card.addrsize)) {
+ Dbprintf("operation failed @ 0x%03.3x", bytes);
+ goto OUT;
+ }
+ }
+
+ // OK
+ DbpString("Write successful");
+
+OUT:
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+ LED_B_OFF();
+ LED_C_OFF();
+ LED_D_OFF();
+ StopTicks();
+}
projects / proxmark3-svn / blobdiff