X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/7cc204bff881ce1d1833d8e93469f6bbba80c70e..28ae37b74612436cc2e5fee4dbcc3e42cc9aaf03:/armsrc/legicrf.c?ds=sidebyside diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c index 3fbdf5cb..97af8843 100644 --- a/armsrc/legicrf.c +++ b/armsrc/legicrf.c @@ -1,5 +1,7 @@ //----------------------------------------------------------------------------- // (c) 2009 Henryk Plötz +// 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 @@ -8,747 +10,448 @@ // 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> 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; iTC_CV < (TAG_TIME_WAIT - 30)) ; - - int i; - for(i=0; iTC_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; iTC_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; iTC_CV < next_bit_at) ; - - next_bit_at += TAG_TIME_BIT; - - for(i=0; iTC_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<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; iPIO_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(); +}