X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/a7247d858b195bd21eeba6d65a882323ad71d030..41dab153055c6bdbbea436b01e7fcf87354c435a:/armsrc/legicrf.c?ds=inline diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c index 867c1ad7..3f3dfbe5 100644 --- a/armsrc/legicrf.c +++ b/armsrc/legicrf.c @@ -8,165 +8,267 @@ #include "apps.h" #include "legicrf.h" +#include "unistd.h" +#include "stdint.h" + +#include "legic_prng.h" +#include "crc.h" static struct legic_frame { - int num_bytes; - int num_bits; - char data[10]; + int bits; + uint16_t data; } current_frame; -static char response = 0x2b; /* 1101 01 */ -static void frame_send(char *response, int num_bytes, int num_bits) +static crc_t legic_crc; + +AT91PS_TC timer; + +static void setup_timer(void) { -#if 0 - /* Use the SSC to send a response. 8-bit transfers, LSBit first, 100us per bit */ -#else - /* 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; - - /* Wait for the frame start */ - while(AT91C_BASE_TC1->TC_CV < 490) ; + /* 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 = TC_CMR_TCCLKS_TIMER_CLOCK3; + timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; + +/* 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 FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz))) + +/* 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<(num_bytes*8+num_bits); i++) { - int nextbit = AT91C_BASE_TC1->TC_CV + 150; - int bit = response[i/8] & (1<<(i%8)); - if(bit) - AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT; - else - AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT; - while(AT91C_BASE_TC1->TC_CV < nextbit) ; + 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) ; } - AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT; -#endif + + { + /* 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 */ } -static void frame_respond(struct legic_frame *f) +/* 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) { - LED_D_ON(); - if(f->num_bytes == 0 && f->num_bits == 7) { - /* This seems to be the initial dialogue, just send 6 bits of static data */ - frame_send(&response, 0, 6); + uint16_t the_bit = 1; /* Use a bitmask to save on shifts */ + uint16_t data=0; + int i, old_level=0, edges=0; + int next_bit_at = TAG_TIME_WAIT; + + + if(bits > 16) + bits = 16; + + 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; inum_bytes >= (int)sizeof(f->data)) - return; /* Overflow, won't happen */ - f->data[f->num_bytes] |= (bit<num_bits); - f->num_bits++; - if(f->num_bits > 7) { - f->num_bits = 0; - f->num_bytes++; + while(timer->TC_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 int frame_is_empty(struct legic_frame *f) +static void frame_clean(struct legic_frame * const f) { - return( (f->num_bytes + f->num_bits) <= 4 ); + f->data = 0; + f->bits = 0; } -static void frame_handle(struct legic_frame *f) +static uint16_t perform_setup_phase_rwd(int iv) { - if( !frame_is_empty(f) ) { - frame_respond(f); - } + + /* Switch on carrier and let the tag charge for 1ms */ + AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT; + SpinDelay(1); + + legic_prng_init(0); /* no keystream yet */ + frame_send_rwd(iv, 7); + legic_prng_init(iv); + + 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); + + if(current_frame.data != 0x1d) + Dbprintf("probably don't know how to deal with %x card", current_frame.data); + return current_frame.data; } -static void frame_clean(struct legic_frame *f) -{ - if(!frame_is_empty(f)) - memset(f->data, 0, sizeof(f->data)); - f->num_bits = 0; - f->num_bytes = 0; +static void LegicCommonInit(void) { + SetAdcMuxFor(GPIO_MUXSEL_HIPKD); + FpgaSetupSsc(); + FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX); + + /* 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; + + setup_timer(); + + crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0); } -static void emit(int bit) +static void switch_off_tag_rwd(void) { - if(bit == -1) { - frame_handle(¤t_frame); - frame_clean(¤t_frame); - } else if(bit == 0) { - frame_append_bit(¤t_frame, 0); - } else if(bit == 1) { - frame_append_bit(¤t_frame, 1); - } + /* Switch off carrier, make sure tag is reset */ + AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT; + SpinDelay(10); + + WDT_HIT(); +} +/* calculate crc for a legic command */ +static int LegicCRC(int byte_index, int value) { + crc_clear(&legic_crc); + crc_update(&legic_crc, 1, 1); /* CMD_READ */ + crc_update(&legic_crc, byte_index, 8); + crc_update(&legic_crc, value, 8); + return crc_finish(&legic_crc); } -void LegicRfSimulate(void) -{ - /* 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. - */ - SetAdcMuxFor(GPIO_MUXSEL_HIPKD); - FpgaSetupSsc(); - FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_212K); +int legic_read_byte(int byte_index) { + int byte; + + legic_prng_forward(4); /* we wait anyways */ + while(timer->TC_CV < 387) ; /* ~ 258us + 100us*delay */ + + frame_send_rwd(1 | (byte_index << 1), 9); + frame_clean(¤t_frame); + + frame_receive_rwd(¤t_frame, 12, 1); + + byte = current_frame.data & 0xff; + if( LegicCRC(byte_index, byte) != (current_frame.data >> 8) ) + Dbprintf("!!! crc mismatch: expected %x but got %x !!!", LegicCRC(byte_index, current_frame.data & 0xff), current_frame.data >> 8); + + return byte; +} + +/* 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 + */ + + +void LegicRfReader(int offset, int bytes) { + int byte_index=0; - /* Bitbang the receiver */ - AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN; - AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN; + LegicCommonInit(); + + memset(BigBuf, 0, 256); - /* 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); - AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS; - AT91C_BASE_TC1->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK3; - AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; - int old_level = 0; + DbpString("setting up legic card"); + perform_setup_phase_rwd(0x55); -/* At TIMER_CLOCK3 (MCK/32) */ -#define BIT_TIME_1 150 -#define BIT_TIME_0 90 -#define BIT_TIME_FUZZ 20 - - int active = 0; - while(!BUTTON_PRESS()) { - int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN); - int time = AT91C_BASE_TC1->TC_CV; - - if(level != old_level) { - if(level == 1) { - AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; - if(time > (BIT_TIME_1-BIT_TIME_FUZZ) && time < (BIT_TIME_1+BIT_TIME_FUZZ)) { - /* 1 bit */ - emit(1); - active = 1; - } else if(time > (BIT_TIME_0-BIT_TIME_FUZZ) && time < (BIT_TIME_0+BIT_TIME_FUZZ)) { - /* 0 bit */ - emit(0); - active = 0; - } else { - /* invalid */ - emit(-1); - active = 0; - } - } - } - - if(time >= (BIT_TIME_1+2*BIT_TIME_FUZZ) && active) { - /* Frame end */ - emit(-1); - active = 0; - } - - if(time >= (20*BIT_TIME_1) && (AT91C_BASE_TC1->TC_SR & AT91C_TC_CLKSTA)) { - AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS; - } - - - old_level = level; - WDT_HIT(); + while(byte_index < bytes) { + ((uint8_t*)BigBuf)[byte_index] = legic_read_byte(byte_index+offset); + byte_index++; } + switch_off_tag_rwd(); + Dbprintf("Card read, use 'data hexsamples %d' to view results", (bytes+7) & ~7); }