X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/4c8db262c093fff0334a048526a69112f939edac..refs/heads/master:/armsrc/legicrf.c diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c index 5b0bf37a..71ff0321 100644 --- a/armsrc/legicrf.c +++ b/armsrc/legicrf.c @@ -1,306 +1,458 @@ -/* - * LEGIC RF simulation code - * - * (c) 2009 Henryk Plötz - */ +//----------------------------------------------------------------------------- +// (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 +// the license. +//----------------------------------------------------------------------------- +// LEGIC RF simulation code +//----------------------------------------------------------------------------- -#include - -#include "apps.h" #include "legicrf.h" -#include "unistd.h" -#include "stdint.h" +#include "proxmark3.h" +#include "apps.h" +#include "usb_cdc.h" +#include "util.h" +#include "string.h" #include "legic_prng.h" +#include "legic.h" #include "crc.h" +#include "fpgaloader.h" -static struct legic_frame { - int bits; - uint32_t data; -} current_frame; - +static legic_card_select_t card;/* metadata of currently selected card */ static crc_t legic_crc; -AT91PS_TC 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 = 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 */ +//----------------------------------------------------------------------------- +// 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 */ + +#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; + } + } +} + +//----------------------------------------------------------------------------- +// 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(); + } + + // 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; + } + + // calculate power + 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); +} +//----------------------------------------------------------------------------- +// 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. +//----------------------------------------------------------------------------- + +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) { }; + + // 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) { }; } -#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; 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 */ +//----------------------------------------------------------------------------- +// 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); } -/* 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 > 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; 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 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); + + // hold sampling until card is expected to respond + last_frame_end += TAG_FRAME_WAIT; + while(GET_TICKS < last_frame_end) { }; + + uint32_t frame = 0; + for(uint8_t i = 0; i < len; ++i) { + frame |= (rx_bit() ^ legic_prng_get_bit()) << i; + legic_prng_forward(1); + + // 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 void frame_clean(struct legic_frame * const f) -{ - f->data = 0; - f->bits = 0; +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); + + // hold sampling until card is expected to respond + last_frame_end += TAG_FRAME_WAIT; + while(GET_TICKS < last_frame_end) { }; + + uint32_t ack = 0; + for(uint8_t i = 0; i < TAG_WRITE_TIMEOUT; ++i) { + // sample bit + ack = rx_bit(); + legic_prng_forward(1); + + // rx_bit runs only 95us, resync to TAG_BIT_PERIOD + last_frame_end += TAG_BIT_PERIOD; + while(GET_TICKS < last_frame_end) { }; + + // check if it was an ACK + if(ack) { + break; + } + } + + return ack; } -static uint32_t perform_setup_phase_rwd(int iv) -{ - - /* 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); - - return current_frame.data; +//----------------------------------------------------------------------------- +// 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; } -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 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(); + + // configure SSC with defaults + FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER); + + // 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); + + // init crc calculator + crc_init(&legic_crc, 4, 0x19 >> 1, 0x05, 0); + + // start us timer + StartTicks(); } -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); - - WDT_HIT(); +// 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; } -/* 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); + +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); } -int legic_read_byte(int byte_index, int cmd_sz) { - int byte; +static int16_t read_byte(uint16_t index, uint8_t cmd_sz) { + uint16_t cmd = (index << 1) | LEGIC_READ; - legic_prng_forward(4); /* we wait anyways */ - while(timer->TC_CV < 387) ; /* ~ 258us + 100us*delay */ + // 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(); - frame_send_rwd(1 | (byte_index << 1), cmd_sz); - frame_clean(¤t_frame); + // split frame into data and crc + uint8_t byte = BYTEx(frame, 0); + uint8_t crc = BYTEx(frame, 1); - frame_receive_rwd(¤t_frame, 12, 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; + } - 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; - } + legic_prng_forward(1); - return byte; + 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 - */ - +// 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(); +} +//----------------------------------------------------------------------------- +// Command Line Interface +// +// Only this functions are public / called from appmain.c +//----------------------------------------------------------------------------- void 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(0x55); - 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); - switch_off_tag_rwd(); - return; - } - if(bytes == -1) { - bytes = card_sz; - } - if(bytes+offset >= card_sz) { - bytes = card_sz-offset; - } - - switch_off_tag_rwd(); //we lost to mutch time with dprintf - perform_setup_phase_rwd(0x55); - - while(byte_index < bytes) { - int r = legic_read_byte(byte_index+offset, cmd_sz); - if(r == -1) { - Dbprintf("aborting"); - switch_off_tag_rwd(); - return; - } - ((uint8_t*)BigBuf)[byte_index] = r; - byte_index++; - } - switch_off_tag_rwd(); - Dbprintf("Card read, use 'hf legic decode' or 'data hexsamples %d' to view results", (bytes+7) & ~7); + 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; + } + + // 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(); +}