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1 //-----------------------------------------------------------------------------
2 // (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // LEGIC RF simulation code
9 //-----------------------------------------------------------------------------
10
11 #include "proxmark3.h"
12 #include "apps.h"
13 #include "util.h"
14 #include "string.h"
15
16 #include "legicrf.h"
17 #include "legic_prng.h"
18 #include "crc.h"
19
20 static struct legic_frame {
21 int bits;
22 uint32_t data;
23 } current_frame;
24
25 static enum {
26 STATE_DISCON,
27 STATE_IV,
28 STATE_CON,
29 } legic_state;
30
31 static crc_t legic_crc;
32 static int legic_read_count;
33 static uint32_t legic_prng_bc;
34 static uint32_t legic_prng_iv;
35
36 static int legic_phase_drift;
37 static int legic_frame_drift;
38 static int legic_reqresp_drift;
39
40 AT91PS_TC timer;
41 AT91PS_TC prng_timer;
42
43 static void setup_timer(void)
44 {
45 /* Set up Timer 1 to use for measuring time between pulses. Since we're bit-banging
46 * this it won't be terribly accurate but should be good enough.
47 */
48 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
49 timer = AT91C_BASE_TC1;
50 timer->TC_CCR = AT91C_TC_CLKDIS;
51 timer->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK;
52 timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
53
54 /*
55 * Set up Timer 2 to use for measuring time between frames in
56 * tag simulation mode. Runs 4x faster as Timer 1
57 */
58 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC2);
59 prng_timer = AT91C_BASE_TC2;
60 prng_timer->TC_CCR = AT91C_TC_CLKDIS;
61 prng_timer->TC_CMR = AT91C_TC_CLKS_TIMER_DIV2_CLOCK;
62 prng_timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
63 }
64
65 /* At TIMER_CLOCK3 (MCK/32) */
66 #define RWD_TIME_1 150 /* RWD_TIME_PAUSE off, 80us on = 100us */
67 #define RWD_TIME_0 90 /* RWD_TIME_PAUSE off, 40us on = 60us */
68 #define RWD_TIME_PAUSE 30 /* 20us */
69 #define RWD_TIME_FUZZ 20 /* rather generous 13us, since the peak detector + hysteresis fuzz quite a bit */
70 #define TAG_TIME_BIT 150 /* 100us for every bit */
71 #define TAG_TIME_WAIT 490 /* time from RWD frame end to tag frame start, experimentally determined */
72
73 #define SIM_DIVISOR 586 /* prng_time/SIM_DIVISOR count prng needs to be forwared */
74 #define SIM_SHIFT 900 /* prng_time+SIM_SHIFT shift of delayed start */
75
76 #define SESSION_IV 0x55
77 #define OFFSET_LOG 1024
78
79 #define FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz)))
80
81 /* Generate Keystream */
82 static uint32_t get_key_stream(int skip, int count)
83 {
84 uint32_t key=0; int i;
85
86 /* Use int to enlarge timer tc to 32bit */
87 legic_prng_bc += prng_timer->TC_CV;
88 prng_timer->TC_CCR = AT91C_TC_SWTRG;
89
90 /* If skip == -1, forward prng time based */
91 if(skip == -1) {
92 i = (legic_prng_bc+SIM_SHIFT)/SIM_DIVISOR; /* Calculate Cycles based on timer */
93 i -= legic_prng_count(); /* substract cycles of finished frames */
94 i -= count; /* substract current frame length, rewidn to bedinning */
95 legic_prng_forward(i);
96 } else {
97 legic_prng_forward(skip);
98 }
99
100 /* Write Time Data into LOG */
101 uint8_t *BigBuf = BigBuf_get_addr();
102 if(count == 6) { i = -1; } else { i = legic_read_count; }
103 BigBuf[OFFSET_LOG+128+i] = legic_prng_count();
104 BigBuf[OFFSET_LOG+256+i*4] = (legic_prng_bc >> 0) & 0xff;
105 BigBuf[OFFSET_LOG+256+i*4+1] = (legic_prng_bc >> 8) & 0xff;
106 BigBuf[OFFSET_LOG+256+i*4+2] = (legic_prng_bc >>16) & 0xff;
107 BigBuf[OFFSET_LOG+256+i*4+3] = (legic_prng_bc >>24) & 0xff;
108 BigBuf[OFFSET_LOG+384+i] = count;
109
110 /* Generate KeyStream */
111 for(i=0; i<count; i++) {
112 key |= legic_prng_get_bit() << i;
113 legic_prng_forward(1);
114 }
115 return key;
116 }
117
118 /* Send a frame in tag mode, the FPGA must have been set up by
119 * LegicRfSimulate
120 */
121 static void frame_send_tag(uint16_t response, int bits, int crypt)
122 {
123 /* Bitbang the response */
124 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
125 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
126 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
127
128 /* Use time to crypt frame */
129 if(crypt) {
130 legic_prng_forward(2); /* TAG_TIME_WAIT -> shift by 2 */
131 int i; int key = 0;
132 for(i=0; i<bits; i++) {
133 key |= legic_prng_get_bit() << i;
134 legic_prng_forward(1);
135 }
136 //Dbprintf("key = 0x%x", key);
137 response = response ^ key;
138 }
139
140 /* Wait for the frame start */
141 while(timer->TC_CV < (TAG_TIME_WAIT - 30)) ;
142
143 int i;
144 for(i=0; i<bits; i++) {
145 int nextbit = timer->TC_CV + TAG_TIME_BIT;
146 int bit = response & 1;
147 response = response >> 1;
148 if(bit) {
149 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
150 } else {
151 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
152 }
153 while(timer->TC_CV < nextbit) ;
154 }
155 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
156 }
157
158 /* Send a frame in reader mode, the FPGA must have been set up by
159 * LegicRfReader
160 */
161 static void frame_send_rwd(uint32_t data, int bits)
162 {
163 /* Start clock */
164 timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
165 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
166
167 int i;
168 for(i=0; i<bits; i++) {
169 int starttime = timer->TC_CV;
170 int pause_end = starttime + RWD_TIME_PAUSE, bit_end;
171 int bit = data & 1;
172 data = data >> 1;
173
174 if(bit ^ legic_prng_get_bit()) {
175 bit_end = starttime + RWD_TIME_1;
176 } else {
177 bit_end = starttime + RWD_TIME_0;
178 }
179
180 /* RWD_TIME_PAUSE time off, then some time on, so that the complete bit time is
181 * RWD_TIME_x, where x is the bit to be transmitted */
182 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
183 while(timer->TC_CV < pause_end) ;
184 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
185 legic_prng_forward(1); /* bit duration is longest. use this time to forward the lfsr */
186
187 while(timer->TC_CV < bit_end) ;
188 }
189
190 {
191 /* One final pause to mark the end of the frame */
192 int pause_end = timer->TC_CV + RWD_TIME_PAUSE;
193 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
194 while(timer->TC_CV < pause_end) ;
195 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
196 }
197
198 /* Reset the timer, to measure time until the start of the tag frame */
199 timer->TC_CCR = AT91C_TC_SWTRG;
200 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
201 }
202
203 /* Receive a frame from the card in reader emulation mode, the FPGA and
204 * timer must have been set up by LegicRfReader and frame_send_rwd.
205 *
206 * The LEGIC RF protocol from card to reader does not include explicit
207 * frame start/stop information or length information. The reader must
208 * know beforehand how many bits it wants to receive. (Notably: a card
209 * sending a stream of 0-bits is indistinguishable from no card present.)
210 *
211 * Receive methodology: There is a fancy correlator in hi_read_rx_xcorr, but
212 * I'm not smart enough to use it. Instead I have patched hi_read_tx to output
213 * the ADC signal with hysteresis on SSP_DIN. Bit-bang that signal and look
214 * for edges. Count the edges in each bit interval. If they are approximately
215 * 0 this was a 0-bit, if they are approximately equal to the number of edges
216 * expected for a 212kHz subcarrier, this was a 1-bit. For timing we use the
217 * timer that's still running from frame_send_rwd in order to get a synchronization
218 * with the frame that we just sent.
219 *
220 * FIXME: Because we're relying on the hysteresis to just do the right thing
221 * the range is severely reduced (and you'll probably also need a good antenna).
222 * So this should be fixed some time in the future for a proper receiver.
223 */
224 static void frame_receive_rwd(struct legic_frame * const f, int bits, int crypt)
225 {
226 uint32_t the_bit = 1; /* Use a bitmask to save on shifts */
227 uint32_t data=0;
228 int i, old_level=0, edges=0;
229 int next_bit_at = TAG_TIME_WAIT;
230
231 if(bits > 32) {
232 bits = 32;
233 }
234
235 AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
236 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
237
238 /* we have some time now, precompute the cipher
239 * since we cannot compute it on the fly while reading */
240 legic_prng_forward(2);
241
242 if(crypt)
243 {
244 for(i=0; i<bits; i++) {
245 data |= legic_prng_get_bit() << i;
246 legic_prng_forward(1);
247 }
248 }
249
250 while(timer->TC_CV < next_bit_at) ;
251
252 next_bit_at += TAG_TIME_BIT;
253
254 for(i=0; i<bits; i++) {
255 edges = 0;
256 while(timer->TC_CV < next_bit_at) {
257 int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
258 if(level != old_level)
259 edges++;
260 old_level = level;
261 }
262 next_bit_at += TAG_TIME_BIT;
263
264 if(edges > 20 && edges < 60) { /* expected are 42 edges */
265 data ^= the_bit;
266 }
267 the_bit <<= 1;
268 }
269
270 f->data = data;
271 f->bits = bits;
272
273 /* Reset the timer, to synchronize the next frame */
274 timer->TC_CCR = AT91C_TC_SWTRG;
275 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
276 }
277
278 static void frame_append_bit(struct legic_frame * const f, int bit)
279 {
280 if(f->bits >= 31) {
281 return; /* Overflow, won't happen */
282 }
283 f->data |= (bit<<f->bits);
284 f->bits++;
285 }
286
287 static void frame_clean(struct legic_frame * const f)
288 {
289 f->data = 0;
290 f->bits = 0;
291 }
292
293 static uint32_t perform_setup_phase_rwd(int iv)
294 {
295
296 /* Switch on carrier and let the tag charge for 1ms */
297 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
298 SpinDelay(1);
299
300 legic_prng_init(0); /* no keystream yet */
301 frame_send_rwd(iv, 7);
302 legic_prng_init(iv);
303
304 frame_clean(&current_frame);
305 frame_receive_rwd(&current_frame, 6, 1);
306 legic_prng_forward(1); /* we wait anyways */
307 while(timer->TC_CV < 387) ; /* ~ 258us */
308 frame_send_rwd(0x19, 6);
309
310 return current_frame.data;
311 }
312
313 static void LegicCommonInit(void) {
314 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
315 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
316 FpgaSetupSsc();
317 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
318
319 /* Bitbang the transmitter */
320 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
321 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
322 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
323
324 setup_timer();
325
326 crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0);
327 }
328
329 static void switch_off_tag_rwd(void)
330 {
331 /* Switch off carrier, make sure tag is reset */
332 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
333 SpinDelay(10);
334
335 WDT_HIT();
336 }
337 /* calculate crc for a legic command */
338 static int LegicCRC(int byte_index, int value, int cmd_sz) {
339 crc_clear(&legic_crc);
340 crc_update(&legic_crc, 1, 1); /* CMD_READ */
341 crc_update(&legic_crc, byte_index, cmd_sz-1);
342 crc_update(&legic_crc, value, 8);
343 return crc_finish(&legic_crc);
344 }
345
346 int legic_read_byte(int byte_index, int cmd_sz) {
347 int byte;
348
349 legic_prng_forward(4); /* we wait anyways */
350 while(timer->TC_CV < 387) ; /* ~ 258us + 100us*delay */
351
352 frame_send_rwd(1 | (byte_index << 1), cmd_sz);
353 frame_clean(&current_frame);
354
355 frame_receive_rwd(&current_frame, 12, 1);
356
357 byte = current_frame.data & 0xff;
358 if( LegicCRC(byte_index, byte, cmd_sz) != (current_frame.data >> 8) ) {
359 Dbprintf("!!! crc mismatch: expected %x but got %x !!!",
360 LegicCRC(byte_index, current_frame.data & 0xff, cmd_sz), current_frame.data >> 8);
361 return -1;
362 }
363
364 return byte;
365 }
366
367 /* legic_write_byte() is not included, however it's trivial to implement
368 * and here are some hints on what remains to be done:
369 *
370 * * assemble a write_cmd_frame with crc and send it
371 * * wait until the tag sends back an ACK ('1' bit unencrypted)
372 * * forward the prng based on the timing
373 */
374 int legic_write_byte(int byte, int addr, int addr_sz) {
375 //do not write UID, CRC, DCF
376 if(addr <= 0x06) {
377 return 0;
378 }
379
380 //== send write command ==============================
381 crc_clear(&legic_crc);
382 crc_update(&legic_crc, 0, 1); /* CMD_WRITE */
383 crc_update(&legic_crc, addr, addr_sz);
384 crc_update(&legic_crc, byte, 8);
385
386 uint32_t crc = crc_finish(&legic_crc);
387 uint32_t cmd = ((crc <<(addr_sz+1+8)) //CRC
388 |(byte <<(addr_sz+1)) //Data
389 |(addr <<1) //Address
390 |(0x00 <<0)); //CMD = W
391 uint32_t cmd_sz = addr_sz+1+8+4; //crc+data+cmd
392
393 legic_prng_forward(2); /* we wait anyways */
394 while(timer->TC_CV < 387) ; /* ~ 258us */
395 frame_send_rwd(cmd, cmd_sz);
396
397 //== wait for ack ====================================
398 int t, old_level=0, edges=0;
399 int next_bit_at =0;
400 while(timer->TC_CV < 387) ; /* ~ 258us */
401 for(t=0; t<80; t++) {
402 edges = 0;
403 next_bit_at += TAG_TIME_BIT;
404 while(timer->TC_CV < next_bit_at) {
405 int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
406 if(level != old_level) {
407 edges++;
408 }
409 old_level = level;
410 }
411 if(edges > 20 && edges < 60) { /* expected are 42 edges */
412 int t = timer->TC_CV;
413 int c = t/TAG_TIME_BIT;
414 timer->TC_CCR = AT91C_TC_SWTRG;
415 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
416 legic_prng_forward(c);
417 return 0;
418 }
419 }
420 timer->TC_CCR = AT91C_TC_SWTRG;
421 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
422 return -1;
423 }
424
425 int LegicRfReader(int offset, int bytes) {
426 int byte_index=0, cmd_sz=0, card_sz=0;
427
428 LegicCommonInit();
429
430 uint8_t *BigBuf = BigBuf_get_addr();
431 memset(BigBuf, 0, 1024);
432
433 DbpString("setting up legic card");
434 uint32_t tag_type = perform_setup_phase_rwd(SESSION_IV);
435 switch_off_tag_rwd(); //we lose to mutch time with dprintf
436 switch(tag_type) {
437 case 0x1d:
438 DbpString("MIM 256 card found, reading card ...");
439 cmd_sz = 9;
440 card_sz = 256;
441 break;
442 case 0x3d:
443 DbpString("MIM 1024 card found, reading card ...");
444 cmd_sz = 11;
445 card_sz = 1024;
446 break;
447 default:
448 Dbprintf("Unknown card format: %x",tag_type);
449 return -1;
450 }
451 if(bytes == -1) {
452 bytes = card_sz;
453 }
454 if(bytes+offset >= card_sz) {
455 bytes = card_sz-offset;
456 }
457
458 perform_setup_phase_rwd(SESSION_IV);
459
460 LED_B_ON();
461 while(byte_index < bytes) {
462 int r = legic_read_byte(byte_index+offset, cmd_sz);
463 if(r == -1 ||BUTTON_PRESS()) {
464 DbpString("operation aborted");
465 switch_off_tag_rwd();
466 LED_B_OFF();
467 LED_C_OFF();
468 return -1;
469 }
470 BigBuf[byte_index] = r;
471 WDT_HIT();
472 byte_index++;
473 if(byte_index & 0x10) LED_C_ON(); else LED_C_OFF();
474 }
475 LED_B_OFF();
476 LED_C_OFF();
477 switch_off_tag_rwd();
478 Dbprintf("Card read, use 'hf legic decode' or");
479 Dbprintf("'data hexsamples %d' to view results", (bytes+7) & ~7);
480 return 0;
481 }
482
483 void LegicRfWriter(int bytes, int offset) {
484 int byte_index=0, addr_sz=0;
485 uint8_t *BigBuf = BigBuf_get_addr();
486
487 LegicCommonInit();
488
489 DbpString("setting up legic card");
490 uint32_t tag_type = perform_setup_phase_rwd(SESSION_IV);
491 switch_off_tag_rwd();
492 switch(tag_type) {
493 case 0x1d:
494 if(offset+bytes > 0x100) {
495 Dbprintf("Error: can not write to 0x%03.3x on MIM 256", offset+bytes);
496 return;
497 }
498 addr_sz = 8;
499 Dbprintf("MIM 256 card found, writing 0x%02.2x - 0x%02.2x ...", offset, offset+bytes);
500 break;
501 case 0x3d:
502 if(offset+bytes > 0x400) {
503 Dbprintf("Error: can not write to 0x%03.3x on MIM 1024", offset+bytes);
504 return;
505 }
506 addr_sz = 10;
507 Dbprintf("MIM 1024 card found, writing 0x%03.3x - 0x%03.3x ...", offset, offset+bytes);
508 break;
509 default:
510 Dbprintf("No or unknown card found, aborting");
511 return;
512 }
513
514 LED_B_ON();
515 perform_setup_phase_rwd(SESSION_IV);
516 legic_prng_forward(2);
517 while(byte_index < bytes) {
518 int r = legic_write_byte(BigBuf[byte_index+offset], byte_index+offset, addr_sz);
519 if((r != 0) || BUTTON_PRESS()) {
520 Dbprintf("operation aborted @ 0x%03.3x", byte_index);
521 switch_off_tag_rwd();
522 LED_B_OFF();
523 LED_C_OFF();
524 return;
525 }
526 WDT_HIT();
527 byte_index++;
528 if(byte_index & 0x10) LED_C_ON(); else LED_C_OFF();
529 }
530 LED_B_OFF();
531 LED_C_OFF();
532 DbpString("write successful");
533 }
534
535 int timestamp;
536
537 /* Handle (whether to respond) a frame in tag mode */
538 static void frame_handle_tag(struct legic_frame const * const f)
539 {
540 uint8_t *BigBuf = BigBuf_get_addr();
541
542 /* First Part of Handshake (IV) */
543 if(f->bits == 7) {
544 if(f->data == SESSION_IV) {
545 LED_C_ON();
546 prng_timer->TC_CCR = AT91C_TC_SWTRG;
547 legic_prng_init(f->data);
548 frame_send_tag(0x3d, 6, 1); /* 0x3d^0x26 = 0x1b */
549 legic_state = STATE_IV;
550 legic_read_count = 0;
551 legic_prng_bc = 0;
552 legic_prng_iv = f->data;
553
554 /* TIMEOUT */
555 timer->TC_CCR = AT91C_TC_SWTRG;
556 while(timer->TC_CV > 1);
557 while(timer->TC_CV < 280);
558 return;
559 } else if((prng_timer->TC_CV % 50) > 40) {
560 legic_prng_init(f->data);
561 frame_send_tag(0x3d, 6, 1);
562 SpinDelay(20);
563 return;
564 }
565 }
566
567 /* 0x19==??? */
568 if(legic_state == STATE_IV) {
569 if((f->bits == 6) && (f->data == (0x19 ^ get_key_stream(1, 6)))) {
570 legic_state = STATE_CON;
571
572 /* TIMEOUT */
573 timer->TC_CCR = AT91C_TC_SWTRG;
574 while(timer->TC_CV > 1);
575 while(timer->TC_CV < 200);
576 return;
577 } else {
578 legic_state = STATE_DISCON;
579 LED_C_OFF();
580 Dbprintf("0x19 - Frame: %03.3x", f->data);
581 return;
582 }
583 }
584
585 /* Read */
586 if(f->bits == 11) {
587 if(legic_state == STATE_CON) {
588 int key = get_key_stream(-1, 11); //legic_phase_drift, 11);
589 int addr = f->data ^ key; addr = addr >> 1;
590 int data = BigBuf[addr];
591 int hash = LegicCRC(addr, data, 11) << 8;
592 BigBuf[OFFSET_LOG+legic_read_count] = (uint8_t)addr;
593 legic_read_count++;
594
595 //Dbprintf("Data:%03.3x, key:%03.3x, addr: %03.3x, read_c:%u", f->data, key, addr, read_c);
596 legic_prng_forward(legic_reqresp_drift);
597
598 frame_send_tag(hash | data, 12, 1);
599
600 /* SHORT TIMEOUT */
601 timer->TC_CCR = AT91C_TC_SWTRG;
602 while(timer->TC_CV > 1);
603 legic_prng_forward(legic_frame_drift);
604 while(timer->TC_CV < 180);
605 return;
606 }
607 }
608
609 /* Write */
610 if(f->bits == 23) {
611 int key = get_key_stream(-1, 23); //legic_frame_drift, 23);
612 int addr = f->data ^ key; addr = addr >> 1; addr = addr & 0x3ff;
613 int data = f->data ^ key; data = data >> 11; data = data & 0xff;
614
615 /* write command */
616 legic_state = STATE_DISCON;
617 LED_C_OFF();
618 Dbprintf("write - addr: %x, data: %x", addr, data);
619 return;
620 }
621
622 if(legic_state != STATE_DISCON) {
623 Dbprintf("Unexpected: sz:%u, Data:%03.3x, State:%u, Count:%u", f->bits, f->data, legic_state, legic_read_count);
624 int i;
625 Dbprintf("IV: %03.3x", legic_prng_iv);
626 for(i = 0; i<legic_read_count; i++) {
627 Dbprintf("Read Nb: %u, Addr: %u", i, BigBuf[OFFSET_LOG+i]);
628 }
629
630 for(i = -1; i<legic_read_count; i++) {
631 uint32_t t;
632 t = BigBuf[OFFSET_LOG+256+i*4];
633 t |= BigBuf[OFFSET_LOG+256+i*4+1] << 8;
634 t |= BigBuf[OFFSET_LOG+256+i*4+2] <<16;
635 t |= BigBuf[OFFSET_LOG+256+i*4+3] <<24;
636
637 Dbprintf("Cycles: %u, Frame Length: %u, Time: %u",
638 BigBuf[OFFSET_LOG+128+i],
639 BigBuf[OFFSET_LOG+384+i],
640 t);
641 }
642 }
643 legic_state = STATE_DISCON;
644 legic_read_count = 0;
645 SpinDelay(10);
646 LED_C_OFF();
647 return;
648 }
649
650 /* Read bit by bit untill full frame is received
651 * Call to process frame end answer
652 */
653 static void emit(int bit)
654 {
655 if(bit == -1) {
656 if(current_frame.bits <= 4) {
657 frame_clean(&current_frame);
658 } else {
659 frame_handle_tag(&current_frame);
660 frame_clean(&current_frame);
661 }
662 WDT_HIT();
663 } else if(bit == 0) {
664 frame_append_bit(&current_frame, 0);
665 } else if(bit == 1) {
666 frame_append_bit(&current_frame, 1);
667 }
668 }
669
670 void LegicRfSimulate(int phase, int frame, int reqresp)
671 {
672 /* ADC path high-frequency peak detector, FPGA in high-frequency simulator mode,
673 * modulation mode set to 212kHz subcarrier. We are getting the incoming raw
674 * envelope waveform on DIN and should send our response on DOUT.
675 *
676 * The LEGIC RF protocol is pulse-pause-encoding from reader to card, so we'll
677 * measure the time between two rising edges on DIN, and no encoding on the
678 * subcarrier from card to reader, so we'll just shift out our verbatim data
679 * on DOUT, 1 bit is 100us. The time from reader to card frame is still unclear,
680 * seems to be 300us-ish.
681 */
682
683 if(phase < 0) {
684 int i;
685 for(i=0; i<=reqresp; i++) {
686 legic_prng_init(SESSION_IV);
687 Dbprintf("i=%u, key 0x%3.3x", i, get_key_stream(i, frame));
688 }
689 return;
690 }
691
692 legic_phase_drift = phase;
693 legic_frame_drift = frame;
694 legic_reqresp_drift = reqresp;
695
696 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
697 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
698 FpgaSetupSsc();
699 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_212K);
700
701 /* Bitbang the receiver */
702 AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
703 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
704
705 setup_timer();
706 crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0);
707
708 int old_level = 0;
709 int active = 0;
710 legic_state = STATE_DISCON;
711
712 LED_B_ON();
713 DbpString("Starting Legic emulator, press button to end");
714 while(!BUTTON_PRESS()) {
715 int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
716 int time = timer->TC_CV;
717
718 if(level != old_level) {
719 if(level == 1) {
720 timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
721 if(FUZZ_EQUAL(time, RWD_TIME_1, RWD_TIME_FUZZ)) {
722 /* 1 bit */
723 emit(1);
724 active = 1;
725 LED_A_ON();
726 } else if(FUZZ_EQUAL(time, RWD_TIME_0, RWD_TIME_FUZZ)) {
727 /* 0 bit */
728 emit(0);
729 active = 1;
730 LED_A_ON();
731 } else if(active) {
732 /* invalid */
733 emit(-1);
734 active = 0;
735 LED_A_OFF();
736 }
737 }
738 }
739
740 if(time >= (RWD_TIME_1+RWD_TIME_FUZZ) && active) {
741 /* Frame end */
742 emit(-1);
743 active = 0;
744 LED_A_OFF();
745 }
746
747 if(time >= (20*RWD_TIME_1) && (timer->TC_SR & AT91C_TC_CLKSTA)) {
748 timer->TC_CCR = AT91C_TC_CLKDIS;
749 }
750
751 old_level = level;
752 WDT_HIT();
753 }
754 DbpString("Stopped");
755 LED_B_OFF();
756 LED_A_OFF();
757 LED_C_OFF();
758 }
759
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