X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/ccedd6ae6b6cde1899635ca9767ccc124db0156a..1b902aa01afa39ff413b74142cd56d092b4500a1:/armsrc/legicrf.c diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c index 6a40b037..c8a4829f 100644 --- a/armsrc/legicrf.c +++ b/armsrc/legicrf.c @@ -1,196 +1,465 @@ -/* - * LEGIC RF simulation code - * - * (c) 2009 Henryk Plötz - */ - -#include +//----------------------------------------------------------------------------- +// (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 "proxmark3.h" #include "apps.h" +#include "util.h" +#include "string.h" + #include "legicrf.h" -#include "unistd.h" -#include "stdint.h" - -static struct legic_frame { - int bits; - uint16_t data; -} current_frame; - -static struct legic_frame queries[] = { - {7, 0x55}, /* 1010 101 */ -}; - -static struct legic_frame responses[] = { - {6, 0x3b}, /* 1101 11 */ -}; - -static void frame_send(uint16_t response, int bits) -{ -#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) ; - - int i; - for(i=0; iTC_CV + 150; - 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(AT91C_BASE_TC1->TC_CV < nextbit) ; - } - AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT; -#endif +#include "legic_prng.h" +#include "legic.h" +#include "crc.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 */ + +#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 uint8_t rx_byte_from_fpga() { + for(;;) { + WDT_HIT(); + + // wait for byte be become available in rx holding register + if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) { + return AT91C_BASE_SSC->SSC_RHR; + } + } } -static void frame_respond(struct legic_frame const * const f) -{ - LED_D_ON(); - int i; - struct legic_frame *r = NULL; - - for(i=0; ibits == queries[i].bits && f->data == queries[i].data) { - r = &responses[i]; - break; - } - } - - if(r != NULL) { - frame_send(r->data, r->bits); - LED_A_ON(); - } else { - LED_A_OFF(); - } - - LED_D_OFF(); +//----------------------------------------------------------------------------- +// 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)) +// +// Note: The SSC receiver is never synchronized the calculation my be performed +// on a I/Q pair from two subsequent correlations, but does not matter. +// +// The bit time is 99.1us (21 I/Q pairs). The receiver skips the first 5 samples +// and averages the next (most stable) 8 samples. The final 8 samples are dropped +// also. +// +// The demedulated should be alligned to the bit periode by the caller. This is +// done in rx_bit and rx_ack. +static inline bool rx_bit() { + int32_t cq = 0; + int32_t ci = 0; + + // skip first 5 I/Q pairs + for(size_t i = 0; i<5; ++i) { + (int8_t)rx_byte_from_fpga(); + (int8_t)rx_byte_from_fpga(); + } + + // sample next 8 I/Q pairs + for(size_t i = 0; i<8; ++i) { + cq += (int8_t)rx_byte_from_fpga(); + ci += (int8_t)rx_byte_from_fpga(); + } + + // calculate power + int32_t power = (MAX(ABS(ci), ABS(cq)) + (MIN(ABS(ci), ABS(cq)) >> 1)); + + // compare average (power / 8) to threshold + return ((power >> 3) > INPUT_THRESHOLD); } -static void frame_append_bit(struct legic_frame * const f, int bit) -{ - if(f->bits >= 15) - return; /* Overflow, won't happen */ - f->data |= (bit<bits); - f->bits++; +//----------------------------------------------------------------------------- +// 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 + LOW(GPIO_SSC_DOUT); + last_frame_end += RWD_TIME_PAUSE; + while(GET_TICKS < last_frame_end) { }; + HIGH(GPIO_SSC_DOUT); + + // return to high, wait for bit periode to end + last_frame_end += (bit ? RWD_TIME_1 : RWD_TIME_0) - RWD_TIME_PAUSE; + while(GET_TICKS < last_frame_end) { }; } -static int frame_is_empty(struct legic_frame const * const f) -{ - return( f->bits <= 4 ); +//----------------------------------------------------------------------------- +// 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_TX); + + // 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 + LOW(GPIO_SSC_DOUT); + last_frame_end += RWD_TIME_PAUSE; + while(GET_TICKS < last_frame_end) { }; + HIGH(GPIO_SSC_DOUT); } -static void frame_handle(struct legic_frame const * const f) -{ - if(f->bits == 6) { - /* Short path */ - return; - } - if( !frame_is_empty(f) ) { - frame_respond(f); - } +static uint32_t rx_frame(uint8_t len) { + FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR + | FPGA_HF_READER_RX_XCORR_848_KHZ + | FPGA_HF_READER_RX_XCORR_QUARTER_FREQ); + + // 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_RX_XCORR + | FPGA_HF_READER_RX_XCORR_848_KHZ + | FPGA_HF_READER_RX_XCORR_QUARTER_FREQ); + + // 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 void emit(int bit) -{ - 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); - } +//----------------------------------------------------------------------------- +// 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; } -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); - - /* Bitbang the receiver */ - AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN; - AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN; - - /* 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; - -/* 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; - LED_B_ON(); - } else if(time > (BIT_TIME_0-BIT_TIME_FUZZ) && time < (BIT_TIME_0+BIT_TIME_FUZZ)) { - /* 0 bit */ - emit(0); - active = 1; - LED_B_ON(); - } else if(active) { - /* invalid */ - emit(-1); - active = 0; - LED_B_OFF(); - } - } - } - - if(time >= (BIT_TIME_1+BIT_TIME_FUZZ) && active) { - /* Frame end */ - emit(-1); - active = 0; - LED_B_OFF(); - } - - 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(); - } +static void init_reader(bool clear_mem) { + // configure FPGA + FpgaDownloadAndGo(FPGA_BITSTREAM_HF); + FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR + | FPGA_HF_READER_RX_XCORR_848_KHZ + | FPGA_HF_READER_RX_XCORR_QUARTER_FREQ); + SetAdcMuxFor(GPIO_MUXSEL_HIPKD); + LED_D_ON(); + + // configure SSC with defaults + FpgaSetupSsc(); + + // re-claim GPIO_SSC_DOUT as GPIO and enable output + AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT; + AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT; + HIGH(GPIO_SSC_DOUT); + + // init crc calculator + crc_init(&legic_crc, 4, 0x19 >> 1, 0x05, 0); + + // start us timer + StartTicks(); +} + +// 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; +} + +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); +} + +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; +} + +// 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) { + 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); + if(init_card(card_type, &card) != 0) { + Dbprintf("No or unknown card found, aborting"); + 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) { + Dbprintf("operation failed @ 0x%03.3x", bytes); + goto OUT; + } + BigBuf[i] = byte; + } + + // OK + Dbprintf("Card (MIM %i) read, use 'hf legic decode' or", card.cardsize); + Dbprintf("'data hexsamples %d' to view results", (bytes+7) & ~7); + +OUT: + 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(); }