X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/1dea88f97640f5979b977a14347c558fabd5496c..b279e3efc16bbf9313fc7d21c8f1c57fa97a198d:/armsrc/legicrf.c

diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c
index bb0badb0..07a930c9 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;
+	uint32_t data;
 } current_frame;
+
+static crc_t legic_crc;
+
 AT91PS_TC timer;
 
 static void setup_timer(void)
@@ -40,49 +46,10 @@ static void setup_timer(void)
 
 #define FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz)))
 
-static const struct legic_frame queries[] = {
-		{7, 0x55}, /* 1010 101 */
-};
-
-static const struct legic_frame responses[] = {
-		{6, 0x3b}, /* 1101 11 */
-};
-
-/* Send a frame in tag mode, the FPGA must have been set up by
- * LegicRfSimulate
- */
-static void frame_send_tag(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(timer->TC_CV < TAG_TIME_WAIT) ;
-	
-	int i;
-	for(i=0; i<bits; i++) {
-		int nextbit = timer->TC_CV + TAG_TIME_BIT;
-		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(timer->TC_CV < nextbit) ;
-	}
-	AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
-#endif
-}
-
 /* 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;
@@ -94,8 +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;
@@ -106,6 +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) ;
 	}
 	
@@ -119,6 +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
@@ -142,10 +112,10 @@ 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;
+	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;
 	
@@ -156,11 +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; 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)
@@ -170,65 +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;
-}
-
-/* Figure out a response to a frame in tag mode */
-static void frame_respond_tag(struct legic_frame const * const f)
-{
-	LED_D_ON();
-	int i, r_size=0;
-	uint16_t r_data=0;
 	
-	for(i=0; i<sizeof(queries)/sizeof(queries[0]); i++) {
-		if(f->bits == queries[i].bits && f->data == queries[i].data) {
-			r_data = responses[i].data;
-			r_size = responses[i].bits;
-			break;
-		}
-	}
-	
-	if(r_size != 0) {
-		frame_send_tag(r_data, r_size);
-		LED_A_ON();
-	} else {
-		LED_A_OFF();
-	}
-	
-	LED_D_OFF();
-}
-
-static void frame_append_bit(struct legic_frame * const f, int bit)
-{
-	if(f->bits >= 15)
-		return; /* Overflow, won't happen */
-	f->data |= (bit<<f->bits);
-	f->bits++;
-}
-
-static int frame_is_empty(struct legic_frame const * const f)
-{
-	return( f->bits <= 4 );
-}
-
-/* Handle (whether to respond) a frame in tag mode */
-static void frame_handle_tag(struct legic_frame const * const f)
-{
-	if(f->bits == 6) {
-		/* Short path */
-		return;
-	}
-	if( !frame_is_empty(f) ) {
-		frame_respond_tag(f);
-	}
+	/* 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)
@@ -237,94 +174,27 @@ static void frame_clean(struct legic_frame * const f)
 	f->bits = 0;
 }
 
-enum emit_mode { 
-	EMIT_RWD, /* Emit in tag simulation mode, e.g. the source is the RWD */
-	EMIT_TAG  /* Emit in reader simulation mode, e.g. the source is the TAG */
-}; 
-static void emit(enum emit_mode mode, int bit)
-{
-	if(bit == -1) {
-		if(mode == EMIT_RWD) {
-			frame_handle_tag(&current_frame);
-		}
-		frame_clean(&current_frame);
-	} else if(bit == 0) {
-		frame_append_bit(&current_frame, 0);
-	} else if(bit == 1) {
-		frame_append_bit(&current_frame, 1);
-	}
-}
-
-void LegicRfSimulate(void)
+static uint32_t perform_setup_phase_rwd(int iv)
 {
-	/* 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;
 	
-	setup_timer();
+	/* Switch on carrier and let the tag charge for 1ms */
+	AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
+	SpinDelay(1);
 	
-	int old_level = 0;
-	int active = 0;
+	legic_prng_init(0); /* no keystream yet */
+	frame_send_rwd(iv, 7);
+        legic_prng_init(iv);
 	
-	while(!BUTTON_PRESS()) {
-		int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
-		int time = timer->TC_CV;
-		
-		if(level != old_level) {
-			if(level == 1) {
-				timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
-				if(FUZZ_EQUAL(time, RWD_TIME_1, RWD_TIME_FUZZ)) {
-					/* 1 bit */
-					emit(EMIT_RWD, 1);
-					active = 1;
-					LED_B_ON();
-				} else if(FUZZ_EQUAL(time, RWD_TIME_0, RWD_TIME_FUZZ)) {
-					/* 0 bit */
-					emit(EMIT_RWD, 0);
-					active = 1;
-					LED_B_ON();
-				} else if(active) {
-					/* invalid */
-					emit(EMIT_RWD, -1);
-					active = 0;
-					LED_B_OFF();
-				}
-			}
-		}
-		
-		if(time >= (RWD_TIME_1+RWD_TIME_FUZZ) && active) {
-			/* Frame end */
-			emit(EMIT_RWD, -1);
-			active = 0;
-			LED_B_OFF();
-		}
-		
-		if(time >= (20*RWD_TIME_1) && (timer->TC_SR & AT91C_TC_CLKSTA)) {
-			timer->TC_CCR = AT91C_TC_CLKDIS;
-		}
-		
-		
-		old_level = level;
-		WDT_HIT();
-	}
+	frame_clean(&current_frame);
+	frame_receive_rwd(&current_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;
 }
 
-void LegicRfReader(void)
-{
+static void LegicCommonInit(void) {
 	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 	FpgaSetupSsc();
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
@@ -336,25 +206,101 @@ 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(&current_frame);
-		LED_B_ON();
-		frame_receive_rwd(&current_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, 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);
+}
+
+int legic_read_byte(int byte_index, int cmd_sz) {
+	int byte;
+
+	legic_prng_forward(4); /* we wait anyways */
+    	while(timer->TC_CV < 387) ; /* ~ 258us + 100us*delay */
+
+	frame_send_rwd(1 | (byte_index << 1), cmd_sz);
+	frame_clean(&current_frame);
+
+	frame_receive_rwd(&current_frame, 12, 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;
 	}
+
+	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, 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 'data hexsamples %d' to view results", (bytes+7) & ~7);
 }
+