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bd20f8f4 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//-----------------------------------------------------------------------------
a7247d85 10
7838f4be 11#include "proxmark3.h"
a7247d85 12#include "apps.h"
f7e3ed82 13#include "util.h"
9ab7a6c7 14#include "string.h"
a7247d85 15
f7e3ed82 16#include "legicrf.h"
7838f4be 17#include "legic_prng.h"
18#include "crc.h"
8e220a91 19
a7247d85 20static struct legic_frame {
ccedd6ae 21 int bits;
a2b1414f 22 uint32_t data;
a7247d85 23} current_frame;
8e220a91 24
3612a8a8 25static enum {
26 STATE_DISCON,
27 STATE_IV,
28 STATE_CON,
29} legic_state;
30
31static crc_t legic_crc;
32static int legic_read_count;
33static uint32_t legic_prng_bc;
34static uint32_t legic_prng_iv;
35
36static int legic_phase_drift;
37static int legic_frame_drift;
38static int legic_reqresp_drift;
8e220a91 39
add16a62 40AT91PS_TC timer;
3612a8a8 41AT91PS_TC prng_timer;
add16a62 42
43static 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;
0aa4cfc2 51 timer->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK;
add16a62 52 timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
53
3612a8a8 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
add16a62 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
3612a8a8 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
add16a62 78
79#define FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz)))
aac23b24 80
3612a8a8 81/* Generate Keystream */
82static uint32_t get_key_stream(int skip, int count)
83{
edaf10af 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 i = (count == 6) ? -1 : legic_read_count;
103
104 BigBuf[OFFSET_LOG+128+i] = legic_prng_count();
105 BigBuf[OFFSET_LOG+256+i*4] = (legic_prng_bc >> 0) & 0xff;
106 BigBuf[OFFSET_LOG+256+i*4+1] = (legic_prng_bc >> 8) & 0xff;
107 BigBuf[OFFSET_LOG+256+i*4+2] = (legic_prng_bc >>16) & 0xff;
108 BigBuf[OFFSET_LOG+256+i*4+3] = (legic_prng_bc >>24) & 0xff;
109 BigBuf[OFFSET_LOG+384+i] = count;
110
111 /* Generate KeyStream */
112 for(i=0; i<count; i++) {
113 key |= legic_prng_get_bit() << i;
114 legic_prng_forward(1);
115 }
116 return key;
3612a8a8 117}
118
119/* Send a frame in tag mode, the FPGA must have been set up by
120 * LegicRfSimulate
121 */
122static void frame_send_tag(uint16_t response, int bits, int crypt)
123{
124 /* Bitbang the response */
125 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
126 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
127 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
128
129 /* Use time to crypt frame */
130 if(crypt) {
131 legic_prng_forward(2); /* TAG_TIME_WAIT -> shift by 2 */
132 int i; int key = 0;
133 for(i=0; i<bits; i++) {
134 key |= legic_prng_get_bit() << i;
135 legic_prng_forward(1);
136 }
137 //Dbprintf("key = 0x%x", key);
138 response = response ^ key;
139 }
140
141 /* Wait for the frame start */
142 while(timer->TC_CV < (TAG_TIME_WAIT - 30)) ;
143
144 int i;
145 for(i=0; i<bits; i++) {
146 int nextbit = timer->TC_CV + TAG_TIME_BIT;
147 int bit = response & 1;
148 response = response >> 1;
edaf10af 149 if(bit)
3612a8a8 150 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
edaf10af 151 else
3612a8a8 152 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
edaf10af 153
3612a8a8 154 while(timer->TC_CV < nextbit) ;
155 }
156 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
157}
158
dcc10e5e 159/* Send a frame in reader mode, the FPGA must have been set up by
160 * LegicRfReader
161 */
8e220a91 162static void frame_send_rwd(uint32_t data, int bits)
dcc10e5e 163{
164 /* Start clock */
165 timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
166 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
e30c654b 167
dcc10e5e 168 int i;
169 for(i=0; i<bits; i++) {
170 int starttime = timer->TC_CV;
171 int pause_end = starttime + RWD_TIME_PAUSE, bit_end;
172 int bit = data & 1;
173 data = data >> 1;
8e220a91 174
edaf10af 175 if(bit ^ legic_prng_get_bit())
dcc10e5e 176 bit_end = starttime + RWD_TIME_1;
edaf10af 177 else
dcc10e5e 178 bit_end = starttime + RWD_TIME_0;
edaf10af 179
e30c654b 180
dcc10e5e 181 /* RWD_TIME_PAUSE time off, then some time on, so that the complete bit time is
182 * RWD_TIME_x, where x is the bit to be transmitted */
183 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
184 while(timer->TC_CV < pause_end) ;
185 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
8e220a91 186 legic_prng_forward(1); /* bit duration is longest. use this time to forward the lfsr */
e30c654b 187
edaf10af 188 while(timer->TC_CV < bit_end);
dcc10e5e 189 }
e30c654b 190
edaf10af 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
e30c654b 197
dcc10e5e 198 /* Reset the timer, to measure time until the start of the tag frame */
199 timer->TC_CCR = AT91C_TC_SWTRG;
2561caa2 200 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
dcc10e5e 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.
e30c654b 205 *
dcc10e5e 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.)
e30c654b 210 *
dcc10e5e 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.
e30c654b 219 *
220 * FIXME: Because we're relying on the hysteresis to just do the right thing
dcc10e5e 221 * the range is severely reduced (and you'll probably also need a good antenna).
e30c654b 222 * So this should be fixed some time in the future for a proper receiver.
dcc10e5e 223 */
8e220a91 224static void frame_receive_rwd(struct legic_frame * const f, int bits, int crypt)
dcc10e5e 225{
a2b1414f 226 uint32_t the_bit = 1; /* Use a bitmask to save on shifts */
227 uint32_t data=0;
dcc10e5e 228 int i, old_level=0, edges=0;
229 int next_bit_at = TAG_TIME_WAIT;
3612a8a8 230
231 if(bits > 32) {
232 bits = 32;
233 }
dcc10e5e 234
235 AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
236 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
237
8e220a91 238 /* we have some time now, precompute the cipher
3612a8a8 239 * since we cannot compute it on the fly while reading */
8e220a91 240 legic_prng_forward(2);
241
edaf10af 242 if(crypt) {
8e220a91 243 for(i=0; i<bits; i++) {
244 data |= legic_prng_get_bit() << i;
245 legic_prng_forward(1);
246 }
247 }
248
dcc10e5e 249 while(timer->TC_CV < next_bit_at) ;
8e220a91 250
dcc10e5e 251 next_bit_at += TAG_TIME_BIT;
e30c654b 252
dcc10e5e 253 for(i=0; i<bits; i++) {
254 edges = 0;
255 while(timer->TC_CV < next_bit_at) {
256 int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
257 if(level != old_level)
258 edges++;
259 old_level = level;
260 }
261 next_bit_at += TAG_TIME_BIT;
3612a8a8 262
dcc10e5e 263 if(edges > 20 && edges < 60) { /* expected are 42 edges */
8e220a91 264 data ^= the_bit;
dcc10e5e 265 }
dcc10e5e 266 the_bit <<= 1;
267 }
e30c654b 268
dcc10e5e 269 f->data = data;
270 f->bits = bits;
e30c654b 271
2561caa2 272 /* Reset the timer, to synchronize the next frame */
273 timer->TC_CCR = AT91C_TC_SWTRG;
274 while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
dcc10e5e 275}
276
3612a8a8 277static void frame_append_bit(struct legic_frame * const f, int bit)
278{
65c2d21d 279 if (f->bits >= 31)
3612a8a8 280 return; /* Overflow, won't happen */
edaf10af 281
65c2d21d 282 f->data |= (bit << f->bits);
3612a8a8 283 f->bits++;
284}
285
ccedd6ae 286static void frame_clean(struct legic_frame * const f)
a7247d85 287{
ccedd6ae 288 f->data = 0;
289 f->bits = 0;
a7247d85 290}
291
a2b1414f 292static uint32_t perform_setup_phase_rwd(int iv)
2561caa2 293{
e30c654b 294
2561caa2 295 /* Switch on carrier and let the tag charge for 1ms */
296 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
297 SpinDelay(1);
e30c654b 298
8e220a91 299 legic_prng_init(0); /* no keystream yet */
300 frame_send_rwd(iv, 7);
3612a8a8 301 legic_prng_init(iv);
e30c654b 302
2561caa2 303 frame_clean(&current_frame);
8e220a91 304 frame_receive_rwd(&current_frame, 6, 1);
305 legic_prng_forward(1); /* we wait anyways */
2561caa2 306 while(timer->TC_CV < 387) ; /* ~ 258us */
8e220a91 307 frame_send_rwd(0x19, 6);
2561caa2 308
8e220a91 309 return current_frame.data;
2561caa2 310}
311
8e220a91 312static void LegicCommonInit(void) {
7cc204bf 313 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
dcc10e5e 314 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
315 FpgaSetupSsc();
316 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
e30c654b 317
dcc10e5e 318 /* Bitbang the transmitter */
319 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
320 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
321 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
e30c654b 322
dcc10e5e 323 setup_timer();
e30c654b 324
8e220a91 325 crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0);
326}
327
328static void switch_off_tag_rwd(void)
329{
330 /* Switch off carrier, make sure tag is reset */
331 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
332 SpinDelay(10);
e30c654b 333
8e220a91 334 WDT_HIT();
335}
336/* calculate crc for a legic command */
a2b1414f 337static int LegicCRC(int byte_index, int value, int cmd_sz) {
8e220a91 338 crc_clear(&legic_crc);
339 crc_update(&legic_crc, 1, 1); /* CMD_READ */
a2b1414f 340 crc_update(&legic_crc, byte_index, cmd_sz-1);
8e220a91 341 crc_update(&legic_crc, value, 8);
342 return crc_finish(&legic_crc);
343}
344
a2b1414f 345int legic_read_byte(int byte_index, int cmd_sz) {
8e220a91 346 int byte;
347
348 legic_prng_forward(4); /* we wait anyways */
3612a8a8 349 while(timer->TC_CV < 387) ; /* ~ 258us + 100us*delay */
8e220a91 350
a2b1414f 351 frame_send_rwd(1 | (byte_index << 1), cmd_sz);
8e220a91 352 frame_clean(&current_frame);
353
354 frame_receive_rwd(&current_frame, 12, 1);
355
356 byte = current_frame.data & 0xff;
65c2d21d 357
a2b1414f 358 if( LegicCRC(byte_index, byte, cmd_sz) != (current_frame.data >> 8) ) {
3612a8a8 359 Dbprintf("!!! crc mismatch: expected %x but got %x !!!",
65c2d21d 360 LegicCRC(byte_index, current_frame.data & 0xff, cmd_sz),
361 current_frame.data >> 8);
a2b1414f 362 return -1;
363 }
8e220a91 364
365 return byte;
366}
367
368/* legic_write_byte() is not included, however it's trivial to implement
369 * and here are some hints on what remains to be done:
370 *
371 * * assemble a write_cmd_frame with crc and send it
372 * * wait until the tag sends back an ACK ('1' bit unencrypted)
373 * * forward the prng based on the timing
374 */
3612a8a8 375int legic_write_byte(int byte, int addr, int addr_sz) {
376 //do not write UID, CRC, DCF
65c2d21d 377 if(addr <= 0x06)
3612a8a8 378 return 0;
8e220a91 379
3612a8a8 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}
8e220a91 424
3612a8a8 425int LegicRfReader(int offset, int bytes) {
a2b1414f 426 int byte_index=0, cmd_sz=0, card_sz=0;
e30c654b 427
8e220a91 428 LegicCommonInit();
429
117d9ec2 430 uint8_t *BigBuf = BigBuf_get_addr();
a2b1414f 431 memset(BigBuf, 0, 1024);
e30c654b 432
8e220a91 433 DbpString("setting up legic card");
3612a8a8 434 uint32_t tag_type = perform_setup_phase_rwd(SESSION_IV);
435 switch_off_tag_rwd(); //we lose to mutch time with dprintf
a2b1414f 436 switch(tag_type) {
437 case 0x1d:
438 DbpString("MIM 256 card found, reading card ...");
3612a8a8 439 cmd_sz = 9;
a2b1414f 440 card_sz = 256;
441 break;
442 case 0x3d:
443 DbpString("MIM 1024 card found, reading card ...");
3612a8a8 444 cmd_sz = 11;
a2b1414f 445 card_sz = 1024;
446 break;
447 default:
b279e3ef 448 Dbprintf("Unknown card format: %x",tag_type);
3612a8a8 449 return -1;
a2b1414f 450 }
edaf10af 451 if(bytes == -1)
a2b1414f 452 bytes = card_sz;
edaf10af 453
454 if(bytes+offset >= card_sz)
a2b1414f 455 bytes = card_sz-offset;
a2b1414f 456
3612a8a8 457 perform_setup_phase_rwd(SESSION_IV);
8e220a91 458
3612a8a8 459 LED_B_ON();
8e220a91 460 while(byte_index < bytes) {
3612a8a8 461 int r = legic_read_byte(byte_index+offset, cmd_sz);
462 if(r == -1 ||BUTTON_PRESS()) {
463 DbpString("operation aborted");
a2b1414f 464 switch_off_tag_rwd();
3612a8a8 465 LED_B_OFF();
466 LED_C_OFF();
467 return -1;
a2b1414f 468 }
117d9ec2 469 BigBuf[byte_index] = r;
3612a8a8 470 WDT_HIT();
2561caa2 471 byte_index++;
3612a8a8 472 if(byte_index & 0x10) LED_C_ON(); else LED_C_OFF();
2561caa2 473 }
3612a8a8 474 LED_B_OFF();
475 LED_C_OFF();
476 switch_off_tag_rwd();
477 Dbprintf("Card read, use 'hf legic decode' or");
478 Dbprintf("'data hexsamples %d' to view results", (bytes+7) & ~7);
479 return 0;
480}
481
482void LegicRfWriter(int bytes, int offset) {
483 int byte_index=0, addr_sz=0;
117d9ec2 484 uint8_t *BigBuf = BigBuf_get_addr();
485
3612a8a8 486 LegicCommonInit();
487
488 DbpString("setting up legic card");
489 uint32_t tag_type = perform_setup_phase_rwd(SESSION_IV);
8e220a91 490 switch_off_tag_rwd();
3612a8a8 491 switch(tag_type) {
492 case 0x1d:
493 if(offset+bytes > 0x100) {
494 Dbprintf("Error: can not write to 0x%03.3x on MIM 256", offset+bytes);
495 return;
496 }
497 addr_sz = 8;
498 Dbprintf("MIM 256 card found, writing 0x%02.2x - 0x%02.2x ...", offset, offset+bytes);
499 break;
500 case 0x3d:
501 if(offset+bytes > 0x400) {
502 Dbprintf("Error: can not write to 0x%03.3x on MIM 1024", offset+bytes);
503 return;
504 }
505 addr_sz = 10;
506 Dbprintf("MIM 1024 card found, writing 0x%03.3x - 0x%03.3x ...", offset, offset+bytes);
507 break;
508 default:
509 Dbprintf("No or unknown card found, aborting");
510 return;
511 }
512
513 LED_B_ON();
514 perform_setup_phase_rwd(SESSION_IV);
515 legic_prng_forward(2);
516 while(byte_index < bytes) {
117d9ec2 517 int r = legic_write_byte(BigBuf[byte_index+offset], byte_index+offset, addr_sz);
3612a8a8 518 if((r != 0) || BUTTON_PRESS()) {
519 Dbprintf("operation aborted @ 0x%03.3x", byte_index);
520 switch_off_tag_rwd();
521 LED_B_OFF();
522 LED_C_OFF();
523 return;
524 }
525 WDT_HIT();
526 byte_index++;
527 if(byte_index & 0x10) LED_C_ON(); else LED_C_OFF();
528 }
529 LED_B_OFF();
530 LED_C_OFF();
531 DbpString("write successful");
532}
533
534int timestamp;
535
536/* Handle (whether to respond) a frame in tag mode */
537static void frame_handle_tag(struct legic_frame const * const f)
538{
117d9ec2 539 uint8_t *BigBuf = BigBuf_get_addr();
540
3612a8a8 541 /* First Part of Handshake (IV) */
542 if(f->bits == 7) {
543 if(f->data == SESSION_IV) {
544 LED_C_ON();
545 prng_timer->TC_CCR = AT91C_TC_SWTRG;
546 legic_prng_init(f->data);
547 frame_send_tag(0x3d, 6, 1); /* 0x3d^0x26 = 0x1b */
548 legic_state = STATE_IV;
549 legic_read_count = 0;
550 legic_prng_bc = 0;
551 legic_prng_iv = f->data;
552
553 /* TIMEOUT */
554 timer->TC_CCR = AT91C_TC_SWTRG;
555 while(timer->TC_CV > 1);
556 while(timer->TC_CV < 280);
557 return;
558 } else if((prng_timer->TC_CV % 50) > 40) {
559 legic_prng_init(f->data);
560 frame_send_tag(0x3d, 6, 1);
561 SpinDelay(20);
562 return;
563 }
564 }
565
566 /* 0x19==??? */
567 if(legic_state == STATE_IV) {
568 if((f->bits == 6) && (f->data == (0x19 ^ get_key_stream(1, 6)))) {
569 legic_state = STATE_CON;
570
571 /* TIMEOUT */
572 timer->TC_CCR = AT91C_TC_SWTRG;
573 while(timer->TC_CV > 1);
574 while(timer->TC_CV < 200);
575 return;
576 } else {
577 legic_state = STATE_DISCON;
578 LED_C_OFF();
579 Dbprintf("0x19 - Frame: %03.3x", f->data);
580 return;
581 }
582 }
583
584 /* Read */
585 if(f->bits == 11) {
586 if(legic_state == STATE_CON) {
587 int key = get_key_stream(-1, 11); //legic_phase_drift, 11);
588 int addr = f->data ^ key; addr = addr >> 1;
117d9ec2 589 int data = BigBuf[addr];
3612a8a8 590 int hash = LegicCRC(addr, data, 11) << 8;
117d9ec2 591 BigBuf[OFFSET_LOG+legic_read_count] = (uint8_t)addr;
3612a8a8 592 legic_read_count++;
593
594 //Dbprintf("Data:%03.3x, key:%03.3x, addr: %03.3x, read_c:%u", f->data, key, addr, read_c);
595 legic_prng_forward(legic_reqresp_drift);
596
597 frame_send_tag(hash | data, 12, 1);
598
599 /* SHORT TIMEOUT */
600 timer->TC_CCR = AT91C_TC_SWTRG;
601 while(timer->TC_CV > 1);
602 legic_prng_forward(legic_frame_drift);
603 while(timer->TC_CV < 180);
604 return;
605 }
606 }
607
608 /* Write */
609 if(f->bits == 23) {
610 int key = get_key_stream(-1, 23); //legic_frame_drift, 23);
611 int addr = f->data ^ key; addr = addr >> 1; addr = addr & 0x3ff;
612 int data = f->data ^ key; data = data >> 11; data = data & 0xff;
613
614 /* write command */
615 legic_state = STATE_DISCON;
616 LED_C_OFF();
617 Dbprintf("write - addr: %x, data: %x", addr, data);
618 return;
619 }
620
621 if(legic_state != STATE_DISCON) {
622 Dbprintf("Unexpected: sz:%u, Data:%03.3x, State:%u, Count:%u", f->bits, f->data, legic_state, legic_read_count);
623 int i;
624 Dbprintf("IV: %03.3x", legic_prng_iv);
625 for(i = 0; i<legic_read_count; i++) {
117d9ec2 626 Dbprintf("Read Nb: %u, Addr: %u", i, BigBuf[OFFSET_LOG+i]);
3612a8a8 627 }
628
629 for(i = -1; i<legic_read_count; i++) {
630 uint32_t t;
117d9ec2 631 t = BigBuf[OFFSET_LOG+256+i*4];
632 t |= BigBuf[OFFSET_LOG+256+i*4+1] << 8;
633 t |= BigBuf[OFFSET_LOG+256+i*4+2] <<16;
634 t |= BigBuf[OFFSET_LOG+256+i*4+3] <<24;
3612a8a8 635
636 Dbprintf("Cycles: %u, Frame Length: %u, Time: %u",
117d9ec2 637 BigBuf[OFFSET_LOG+128+i],
638 BigBuf[OFFSET_LOG+384+i],
3612a8a8 639 t);
640 }
641 }
642 legic_state = STATE_DISCON;
643 legic_read_count = 0;
644 SpinDelay(10);
645 LED_C_OFF();
646 return;
647}
648
649/* Read bit by bit untill full frame is received
650 * Call to process frame end answer
651 */
652static void emit(int bit)
653{
654 if(bit == -1) {
655 if(current_frame.bits <= 4) {
656 frame_clean(&current_frame);
657 } else {
658 frame_handle_tag(&current_frame);
659 frame_clean(&current_frame);
660 }
661 WDT_HIT();
662 } else if(bit == 0) {
663 frame_append_bit(&current_frame, 0);
664 } else if(bit == 1) {
665 frame_append_bit(&current_frame, 1);
666 }
667}
668
669void LegicRfSimulate(int phase, int frame, int reqresp)
670{
671 /* ADC path high-frequency peak detector, FPGA in high-frequency simulator mode,
672 * modulation mode set to 212kHz subcarrier. We are getting the incoming raw
673 * envelope waveform on DIN and should send our response on DOUT.
674 *
675 * The LEGIC RF protocol is pulse-pause-encoding from reader to card, so we'll
676 * measure the time between two rising edges on DIN, and no encoding on the
677 * subcarrier from card to reader, so we'll just shift out our verbatim data
678 * on DOUT, 1 bit is 100us. The time from reader to card frame is still unclear,
679 * seems to be 300us-ish.
680 */
681
682 if(phase < 0) {
683 int i;
684 for(i=0; i<=reqresp; i++) {
685 legic_prng_init(SESSION_IV);
686 Dbprintf("i=%u, key 0x%3.3x", i, get_key_stream(i, frame));
687 }
688 return;
689 }
690
691 legic_phase_drift = phase;
692 legic_frame_drift = frame;
693 legic_reqresp_drift = reqresp;
694
7cc204bf 695 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
3612a8a8 696 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
697 FpgaSetupSsc();
698 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_212K);
699
700 /* Bitbang the receiver */
701 AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
702 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
703
704 setup_timer();
705 crc_init(&legic_crc, 4, 0x19 >> 1, 0x5, 0);
706
707 int old_level = 0;
708 int active = 0;
709 legic_state = STATE_DISCON;
710
711 LED_B_ON();
712 DbpString("Starting Legic emulator, press button to end");
6427695b 713 while(!BUTTON_PRESS() && !usb_poll_validate_length()) {
3612a8a8 714 int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
715 int time = timer->TC_CV;
716
717 if(level != old_level) {
718 if(level == 1) {
719 timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
720 if(FUZZ_EQUAL(time, RWD_TIME_1, RWD_TIME_FUZZ)) {
721 /* 1 bit */
722 emit(1);
723 active = 1;
724 LED_A_ON();
725 } else if(FUZZ_EQUAL(time, RWD_TIME_0, RWD_TIME_FUZZ)) {
726 /* 0 bit */
727 emit(0);
728 active = 1;
729 LED_A_ON();
730 } else if(active) {
731 /* invalid */
732 emit(-1);
733 active = 0;
734 LED_A_OFF();
735 }
736 }
737 }
738
739 if(time >= (RWD_TIME_1+RWD_TIME_FUZZ) && active) {
740 /* Frame end */
741 emit(-1);
742 active = 0;
743 LED_A_OFF();
744 }
745
746 if(time >= (20*RWD_TIME_1) && (timer->TC_SR & AT91C_TC_CLKSTA)) {
747 timer->TC_CCR = AT91C_TC_CLKDIS;
748 }
749
750 old_level = level;
751 WDT_HIT();
752 }
753 DbpString("Stopped");
754 LED_B_OFF();
755 LED_A_OFF();
756 LED_C_OFF();
dcc10e5e 757}
a2b1414f 758
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