#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)
/* 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;
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;
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) ;
}
* 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;
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; i<bits; i++) {
+ data |= legic_prng_get_bit() << i;
+ legic_prng_forward(1);
+ }
+ }
+
while(timer->TC_CV < next_bit_at) ;
+
next_bit_at += TAG_TIME_BIT;
for(i=0; i<bits; i++) {
edges = 0;
+
while(timer->TC_CV < next_bit_at) {
int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
if(level != old_level)
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->bits = 0;
}
-static uint16_t perform_setup_phase_rwd(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);
- frame_send_rwd(0x55, 7);
+ 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);
+ frame_receive_rwd(¤t_frame, 6, 1);
+ legic_prng_forward(1); /* we wait anyways */
while(timer->TC_CV < 387) ; /* ~ 258us */
- frame_send_rwd(0x019, 6);
-
- return current_frame.data ^ 0x26;
-}
+ frame_send_rwd(0x19, 6);
-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();
+ if(current_frame.data != 0x1d)
+ Dbprintf("probably don't know how to deal with %x card", current_frame.data);
+ return current_frame.data;
}
-void LegicRfReader(void)
-{
+static void LegicCommonInit(void) {
SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
FpgaSetupSsc();
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
setup_timer();
- memset(BigBuf, 0, 1024);
+ 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);
- int byte_index = 0, card_size = 0, command_size = 0;
- uint16_t command_obfuscation = 0x57, response_obfuscation = 0;
- uint16_t tag_type = perform_setup_phase_rwd();
- switch_off_tag_rwd();
+ 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;
- int error = 0;
- switch(tag_type) {
- case 0x1d:
- DbpString("MIM 256 card found, reading card ...");
- command_size = 9;
- card_size = 256;
- response_obfuscation = 0x52;
- break;
- case 0x3d:
- DbpString("MIM 1024 card found, reading card ...");
- command_size = 11;
- card_size = 1024;
- response_obfuscation = 0xd4;
- break;
- default:
- DbpString("No or unknown card found, aborting");
- error = 1;
- break;
- }
+ LegicCommonInit();
+
+ memset(BigBuf, 0, 256);
- LED_B_ON();
- while(!BUTTON_PRESS() && (byte_index<card_size)) {
- if(perform_setup_phase_rwd() != tag_type) {
- DbpString("Card removed, aborting");
- switch_off_tag_rwd();
- error=1;
- break;
- }
-
- while(timer->TC_CV < 387) ; /* ~ 258us */
- frame_send_rwd(command_obfuscation ^ (byte_index<<1), command_size);
- frame_clean(¤t_frame);
- frame_receive_rwd(¤t_frame, 8);
- ((uint8_t*)BigBuf)[byte_index] = (current_frame.data ^ response_obfuscation) & 0xff;
-
- switch_off_tag_rwd();
-
- WDT_HIT();
+ 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++;
- if(byte_index & 0x04) LED_C_ON(); else LED_C_OFF();
- }
- LED_B_OFF();
- LED_C_OFF();
-
- if(!error) {
- if(card_size == 256) {
- DbpString("Card read, use hexsamples 256 to view results");
- } else if(card_size == 1024) {
- DbpString("Card read, use hexsamples 1024 to view results");
- }
}
+ switch_off_tag_rwd();
+ Dbprintf("Card read, use 'data hexsamples %d' to view results", (bytes+7) & ~7);
}
projects / proxmark3-svn / commitdiff