X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/1d99b0df4a0c1a2f42fe23ae32cc8f3d090bc985..8e220a91260072f1483f1fb41d6ce64459667e4c:/armsrc/legicrf.c diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c index 7c3460af..3f3dfbe5 100644 --- a/armsrc/legicrf.c +++ b/armsrc/legicrf.c @@ -11,10 +11,16 @@ #include "unistd.h" #include "stdint.h" +#include "legic_prng.h" +#include "crc.h" + static struct legic_frame { int bits; uint16_t data; } current_frame; + +static crc_t legic_crc; + AT91PS_TC timer; static void setup_timer(void) @@ -43,7 +49,7 @@ static void setup_timer(void) /* Send a frame in reader mode, the FPGA must have been set up by * LegicRfReader */ -static void frame_send_rwd(uint16_t data, int bits) +static void frame_send_rwd(uint32_t data, int bits) { /* Start clock */ timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; @@ -55,8 +61,8 @@ static void frame_send_rwd(uint16_t data, int bits) int pause_end = starttime + RWD_TIME_PAUSE, bit_end; int bit = data & 1; data = data >> 1; - - if(bit) { + + if(bit ^ legic_prng_get_bit()) { bit_end = starttime + RWD_TIME_1; } else { bit_end = starttime + RWD_TIME_0; @@ -67,6 +73,8 @@ static void frame_send_rwd(uint16_t data, int bits) 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) ; } @@ -80,6 +88,7 @@ static void frame_send_rwd(uint16_t data, int bits) /* 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 */ } /* Receive a frame from the card in reader emulation mode, the FPGA and @@ -103,7 +112,7 @@ static void frame_send_rwd(uint16_t data, int bits) * 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) +static void frame_receive_rwd(struct legic_frame * const f, int bits, int crypt) { uint16_t the_bit = 1; /* Use a bitmask to save on shifts */ uint16_t data=0; @@ -117,11 +126,25 @@ static void frame_receive_rwd(struct legic_frame * const f, int bits) 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) @@ -131,15 +154,18 @@ static void frame_receive_rwd(struct legic_frame * const f, int bits) next_bit_at += TAG_TIME_BIT; if(edges > 20 && edges < 60) { /* expected are 42 edges */ - data |= the_bit; + 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 void frame_clean(struct legic_frame * const f) @@ -148,8 +174,29 @@ static void frame_clean(struct legic_frame * const f) f->bits = 0; } -void LegicRfReader(void) +static uint16_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); + + 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 LegicCommonInit(void) { SetAdcMuxFor(GPIO_MUXSEL_HIPKD); FpgaSetupSsc(); FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX); @@ -161,25 +208,67 @@ void LegicRfReader(void) setup_timer(); - while(!BUTTON_PRESS()) { - /* Switch on carrier and let the tag charge for 1ms */ - AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT; - SpinDelay(1); - - LED_A_ON(); - frame_send_rwd(queries[0].data, queries[0].bits); - LED_A_OFF(); - - frame_clean(¤t_frame); - LED_B_ON(); - frame_receive_rwd(¤t_frame, responses[0].bits); - LED_B_OFF(); - - /* Switch off carrier, make sure tag is reset */ - AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT; - SpinDelay(10); - - WDT_HIT(); - } + crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0); +} + +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(); +} +/* 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); +} + +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; + + LegicCommonInit(); + + memset(BigBuf, 0, 256); + + DbpString("setting up legic card"); + perform_setup_phase_rwd(0x55); + + 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); }