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1 //-----------------------------------------------------------------------------
2 // Jonathan Westhues, split Nov 2006
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 // Routines to support ISO 14443B. This includes both the reader software and
9 // the `fake tag' modes.
10 //-----------------------------------------------------------------------------
11
12 #include "proxmark3.h"
13 #include "apps.h"
14 #include "util.h"
15 #include "string.h"
16
17 #include "iso14443crc.h"
18
19 #define RECEIVE_SAMPLES_TIMEOUT 2000
20 #define ISO14443B_DMA_BUFFER_SIZE 256
21
22 //=============================================================================
23 // An ISO 14443 Type B tag. We listen for commands from the reader, using
24 // a UART kind of thing that's implemented in software. When we get a
25 // frame (i.e., a group of bytes between SOF and EOF), we check the CRC.
26 // If it's good, then we can do something appropriate with it, and send
27 // a response.
28 //=============================================================================
29
30 //-----------------------------------------------------------------------------
31 // Code up a string of octets at layer 2 (including CRC, we don't generate
32 // that here) so that they can be transmitted to the reader. Doesn't transmit
33 // them yet, just leaves them ready to send in ToSend[].
34 //-----------------------------------------------------------------------------
35 static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
36 {
37 int i;
38
39 ToSendReset();
40
41 // Transmit a burst of ones, as the initial thing that lets the
42 // reader get phase sync. This (TR1) must be > 80/fs, per spec,
43 // but tag that I've tried (a Paypass) exceeds that by a fair bit,
44 // so I will too.
45 for(i = 0; i < 20; i++) {
46 ToSendStuffBit(1);
47 ToSendStuffBit(1);
48 ToSendStuffBit(1);
49 ToSendStuffBit(1);
50 }
51
52 // Send SOF.
53 for(i = 0; i < 10; i++) {
54 ToSendStuffBit(0);
55 ToSendStuffBit(0);
56 ToSendStuffBit(0);
57 ToSendStuffBit(0);
58 }
59 for(i = 0; i < 2; i++) {
60 ToSendStuffBit(1);
61 ToSendStuffBit(1);
62 ToSendStuffBit(1);
63 ToSendStuffBit(1);
64 }
65
66 for(i = 0; i < len; i++) {
67 int j;
68 uint8_t b = cmd[i];
69
70 // Start bit
71 ToSendStuffBit(0);
72 ToSendStuffBit(0);
73 ToSendStuffBit(0);
74 ToSendStuffBit(0);
75
76 // Data bits
77 for(j = 0; j < 8; j++) {
78 if(b & 1) {
79 ToSendStuffBit(1);
80 ToSendStuffBit(1);
81 ToSendStuffBit(1);
82 ToSendStuffBit(1);
83 } else {
84 ToSendStuffBit(0);
85 ToSendStuffBit(0);
86 ToSendStuffBit(0);
87 ToSendStuffBit(0);
88 }
89 b >>= 1;
90 }
91
92 // Stop bit
93 ToSendStuffBit(1);
94 ToSendStuffBit(1);
95 ToSendStuffBit(1);
96 ToSendStuffBit(1);
97 }
98
99 // Send EOF.
100 for(i = 0; i < 10; i++) {
101 ToSendStuffBit(0);
102 ToSendStuffBit(0);
103 ToSendStuffBit(0);
104 ToSendStuffBit(0);
105 }
106 for(i = 0; i < 2; i++) {
107 ToSendStuffBit(1);
108 ToSendStuffBit(1);
109 ToSendStuffBit(1);
110 ToSendStuffBit(1);
111 }
112
113 // Convert from last byte pos to length
114 ToSendMax++;
115 }
116
117 //-----------------------------------------------------------------------------
118 // The software UART that receives commands from the reader, and its state
119 // variables.
120 //-----------------------------------------------------------------------------
121 static struct {
122 enum {
123 STATE_UNSYNCD,
124 STATE_GOT_FALLING_EDGE_OF_SOF,
125 STATE_AWAITING_START_BIT,
126 STATE_RECEIVING_DATA
127 } state;
128 uint16_t shiftReg;
129 int bitCnt;
130 int byteCnt;
131 int byteCntMax;
132 int posCnt;
133 uint8_t *output;
134 } Uart;
135
136 /* Receive & handle a bit coming from the reader.
137 *
138 * This function is called 4 times per bit (every 2 subcarrier cycles).
139 * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
140 *
141 * LED handling:
142 * LED A -> ON once we have received the SOF and are expecting the rest.
143 * LED A -> OFF once we have received EOF or are in error state or unsynced
144 *
145 * Returns: true if we received a EOF
146 * false if we are still waiting for some more
147 */
148 static RAMFUNC int Handle14443bUartBit(uint8_t bit)
149 {
150 switch(Uart.state) {
151 case STATE_UNSYNCD:
152 if(!bit) {
153 // we went low, so this could be the beginning
154 // of an SOF
155 Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
156 Uart.posCnt = 0;
157 Uart.bitCnt = 0;
158 }
159 break;
160
161 case STATE_GOT_FALLING_EDGE_OF_SOF:
162 Uart.posCnt++;
163 if(Uart.posCnt == 2) { // sample every 4 1/fs in the middle of a bit
164 if(bit) {
165 if(Uart.bitCnt > 9) {
166 // we've seen enough consecutive
167 // zeros that it's a valid SOF
168 Uart.posCnt = 0;
169 Uart.byteCnt = 0;
170 Uart.state = STATE_AWAITING_START_BIT;
171 LED_A_ON(); // Indicate we got a valid SOF
172 } else {
173 // didn't stay down long enough
174 // before going high, error
175 Uart.state = STATE_UNSYNCD;
176 }
177 } else {
178 // do nothing, keep waiting
179 }
180 Uart.bitCnt++;
181 }
182 if(Uart.posCnt >= 4) Uart.posCnt = 0;
183 if(Uart.bitCnt > 12) {
184 // Give up if we see too many zeros without
185 // a one, too.
186 LED_A_OFF();
187 Uart.state = STATE_UNSYNCD;
188 }
189 break;
190
191 case STATE_AWAITING_START_BIT:
192 Uart.posCnt++;
193 if(bit) {
194 if(Uart.posCnt > 50/2) { // max 57us between characters = 49 1/fs, max 3 etus after low phase of SOF = 24 1/fs
195 // stayed high for too long between
196 // characters, error
197 Uart.state = STATE_UNSYNCD;
198 }
199 } else {
200 // falling edge, this starts the data byte
201 Uart.posCnt = 0;
202 Uart.bitCnt = 0;
203 Uart.shiftReg = 0;
204 Uart.state = STATE_RECEIVING_DATA;
205 }
206 break;
207
208 case STATE_RECEIVING_DATA:
209 Uart.posCnt++;
210 if(Uart.posCnt == 2) {
211 // time to sample a bit
212 Uart.shiftReg >>= 1;
213 if(bit) {
214 Uart.shiftReg |= 0x200;
215 }
216 Uart.bitCnt++;
217 }
218 if(Uart.posCnt >= 4) {
219 Uart.posCnt = 0;
220 }
221 if(Uart.bitCnt == 10) {
222 if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
223 {
224 // this is a data byte, with correct
225 // start and stop bits
226 Uart.output[Uart.byteCnt] = (Uart.shiftReg >> 1) & 0xff;
227 Uart.byteCnt++;
228
229 if(Uart.byteCnt >= Uart.byteCntMax) {
230 // Buffer overflowed, give up
231 LED_A_OFF();
232 Uart.state = STATE_UNSYNCD;
233 } else {
234 // so get the next byte now
235 Uart.posCnt = 0;
236 Uart.state = STATE_AWAITING_START_BIT;
237 }
238 } else if (Uart.shiftReg == 0x000) {
239 // this is an EOF byte
240 LED_A_OFF(); // Finished receiving
241 Uart.state = STATE_UNSYNCD;
242 if (Uart.byteCnt != 0) {
243 return TRUE;
244 }
245 } else {
246 // this is an error
247 LED_A_OFF();
248 Uart.state = STATE_UNSYNCD;
249 }
250 }
251 break;
252
253 default:
254 LED_A_OFF();
255 Uart.state = STATE_UNSYNCD;
256 break;
257 }
258
259 return FALSE;
260 }
261
262
263 static void UartReset()
264 {
265 Uart.byteCntMax = MAX_FRAME_SIZE;
266 Uart.state = STATE_UNSYNCD;
267 Uart.byteCnt = 0;
268 Uart.bitCnt = 0;
269 }
270
271
272 static void UartInit(uint8_t *data)
273 {
274 Uart.output = data;
275 UartReset();
276 }
277
278
279 //-----------------------------------------------------------------------------
280 // Receive a command (from the reader to us, where we are the simulated tag),
281 // and store it in the given buffer, up to the given maximum length. Keeps
282 // spinning, waiting for a well-framed command, until either we get one
283 // (returns TRUE) or someone presses the pushbutton on the board (FALSE).
284 //
285 // Assume that we're called with the SSC (to the FPGA) and ADC path set
286 // correctly.
287 //-----------------------------------------------------------------------------
288 static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
289 {
290 // Set FPGA mode to "simulated ISO 14443B tag", no modulation (listen
291 // only, since we are receiving, not transmitting).
292 // Signal field is off with the appropriate LED
293 LED_D_OFF();
294 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
295
296 // Now run a `software UART' on the stream of incoming samples.
297 UartInit(received);
298
299 for(;;) {
300 WDT_HIT();
301
302 if(BUTTON_PRESS()) return FALSE;
303
304 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
305 uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
306 for(uint8_t mask = 0x80; mask != 0x00; mask >>= 1) {
307 if(Handle14443bUartBit(b & mask)) {
308 *len = Uart.byteCnt;
309 return TRUE;
310 }
311 }
312 }
313 }
314
315 return FALSE;
316 }
317
318 //-----------------------------------------------------------------------------
319 // Main loop of simulated tag: receive commands from reader, decide what
320 // response to send, and send it.
321 //-----------------------------------------------------------------------------
322 void SimulateIso14443bTag(void)
323 {
324 // the only commands we understand is REQB, AFI=0, Select All, N=8:
325 static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 }; // REQB
326 // ... and REQB, AFI=0, Normal Request, N=0:
327 static const uint8_t cmd2[] = { 0x05, 0x00, 0x00, 0x71, 0xFF }; // REQB
328 // ... and WUPB, AFI=0, N=8:
329 static const uint8_t cmd3[] = { 0x05, 0x08, 0x08, 0xF9, 0xBD }; // WUPB
330 // ... and HLTB
331 static const uint8_t cmd4[] = { 0x50, 0xff, 0xff, 0xff, 0xff }; // HLTB
332 // ... and ATTRIB
333 static const uint8_t cmd5[] = { 0x1D, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; // ATTRIB
334
335 // ... and we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
336 // supports only 106kBit/s in both directions, max frame size = 32Bytes,
337 // supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:
338 static const uint8_t response1[] = {
339 0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
340 0x00, 0x21, 0x85, 0x5e, 0xd7
341 };
342 // response to HLTB and ATTRIB
343 static const uint8_t response2[] = {0x00, 0x78, 0xF0};
344
345
346 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
347
348 clear_trace();
349 set_tracing(TRUE);
350
351 const uint8_t *resp;
352 uint8_t *respCode;
353 uint16_t respLen, respCodeLen;
354
355 // allocate command receive buffer
356 BigBuf_free();
357 uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
358
359 uint16_t len;
360 uint16_t cmdsRecvd = 0;
361
362 // prepare the (only one) tag answer:
363 CodeIso14443bAsTag(response1, sizeof(response1));
364 uint8_t *resp1Code = BigBuf_malloc(ToSendMax);
365 memcpy(resp1Code, ToSend, ToSendMax);
366 uint16_t resp1CodeLen = ToSendMax;
367
368 // prepare the (other) tag answer:
369 CodeIso14443bAsTag(response2, sizeof(response2));
370 uint8_t *resp2Code = BigBuf_malloc(ToSendMax);
371 memcpy(resp2Code, ToSend, ToSendMax);
372 uint16_t resp2CodeLen = ToSendMax;
373
374 // We need to listen to the high-frequency, peak-detected path.
375 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
376 FpgaSetupSsc();
377
378 cmdsRecvd = 0;
379
380 for(;;) {
381
382 if(!GetIso14443bCommandFromReader(receivedCmd, &len)) {
383 Dbprintf("button pressed, received %d commands", cmdsRecvd);
384 break;
385 }
386
387 if (tracing) {
388 uint8_t parity[MAX_PARITY_SIZE];
389 LogTrace(receivedCmd, len, 0, 0, parity, TRUE);
390 }
391
392 // Good, look at the command now.
393 if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
394 || (len == sizeof(cmd2) && memcmp(receivedCmd, cmd2, len) == 0)
395 || (len == sizeof(cmd3) && memcmp(receivedCmd, cmd3, len) == 0) ) {
396 resp = response1;
397 respLen = sizeof(response1);
398 respCode = resp1Code;
399 respCodeLen = resp1CodeLen;
400 } else if ( (len == sizeof(cmd4) && receivedCmd[0] == cmd4[0])
401 || (len == sizeof(cmd5) && receivedCmd[0] == cmd5[0]) ) {
402 resp = response2;
403 respLen = sizeof(response2);
404 respCode = resp2Code;
405 respCodeLen = resp2CodeLen;
406 } else {
407 Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
408 // And print whether the CRC fails, just for good measure
409 uint8_t b1, b2;
410 if (len >= 3){ // if crc exists
411 ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
412 if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
413 // Not so good, try again.
414 DbpString("+++CRC fail");
415 } else {
416 DbpString("CRC passes");
417 }
418 }
419 //get rid of compiler warning
420 respCodeLen = 0;
421 resp = response1;
422 respLen = 0;
423 respCode = resp1Code;
424 //don't crash at new command just wait and see if reader will send other new cmds.
425 //break;
426 }
427
428 cmdsRecvd++;
429
430 if(cmdsRecvd > 0x30) {
431 DbpString("many commands later...");
432 break;
433 }
434
435 if(respCodeLen <= 0) continue;
436
437 // Modulate BPSK
438 // Signal field is off with the appropriate LED
439 LED_D_OFF();
440 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
441 AT91C_BASE_SSC->SSC_THR = 0xff;
442 FpgaSetupSsc();
443
444 // Transmit the response.
445 uint16_t i = 0;
446 for(;;) {
447 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
448 uint8_t b = respCode[i];
449
450 AT91C_BASE_SSC->SSC_THR = b;
451
452 i++;
453 if(i > respCodeLen) {
454 break;
455 }
456 }
457 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
458 volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
459 (void)b;
460 }
461 }
462
463 // trace the response:
464 if (tracing) {
465 uint8_t parity[MAX_PARITY_SIZE];
466 LogTrace(resp, respLen, 0, 0, parity, FALSE);
467 }
468
469 }
470 }
471
472 //=============================================================================
473 // An ISO 14443 Type B reader. We take layer two commands, code them
474 // appropriately, and then send them to the tag. We then listen for the
475 // tag's response, which we leave in the buffer to be demodulated on the
476 // PC side.
477 //=============================================================================
478
479 static struct {
480 enum {
481 DEMOD_UNSYNCD,
482 DEMOD_PHASE_REF_TRAINING,
483 DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
484 DEMOD_GOT_FALLING_EDGE_OF_SOF,
485 DEMOD_AWAITING_START_BIT,
486 DEMOD_RECEIVING_DATA
487 } state;
488 int bitCount;
489 int posCount;
490 int thisBit;
491 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
492 int metric;
493 int metricN;
494 */
495 uint16_t shiftReg;
496 uint8_t *output;
497 int len;
498 int sumI;
499 int sumQ;
500 } Demod;
501
502 /*
503 * Handles reception of a bit from the tag
504 *
505 * This function is called 2 times per bit (every 4 subcarrier cycles).
506 * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 4,72us
507 *
508 * LED handling:
509 * LED C -> ON once we have received the SOF and are expecting the rest.
510 * LED C -> OFF once we have received EOF or are unsynced
511 *
512 * Returns: true if we received a EOF
513 * false if we are still waiting for some more
514 *
515 */
516 static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
517 {
518 int v;
519
520 // The soft decision on the bit uses an estimate of just the
521 // quadrant of the reference angle, not the exact angle.
522 #define MAKE_SOFT_DECISION() { \
523 if(Demod.sumI > 0) { \
524 v = ci; \
525 } else { \
526 v = -ci; \
527 } \
528 if(Demod.sumQ > 0) { \
529 v += cq; \
530 } else { \
531 v -= cq; \
532 } \
533 }
534
535 #define SUBCARRIER_DETECT_THRESHOLD 8
536
537 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by abs(ci) + abs(cq)
538 /* #define CHECK_FOR_SUBCARRIER() { \
539 v = ci; \
540 if(v < 0) v = -v; \
541 if(cq > 0) { \
542 v += cq; \
543 } else { \
544 v -= cq; \
545 } \
546 }
547 */
548 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
549 #define CHECK_FOR_SUBCARRIER() { \
550 if(ci < 0) { \
551 if(cq < 0) { /* ci < 0, cq < 0 */ \
552 if (cq < ci) { \
553 v = -cq - (ci >> 1); \
554 } else { \
555 v = -ci - (cq >> 1); \
556 } \
557 } else { /* ci < 0, cq >= 0 */ \
558 if (cq < -ci) { \
559 v = -ci + (cq >> 1); \
560 } else { \
561 v = cq - (ci >> 1); \
562 } \
563 } \
564 } else { \
565 if(cq < 0) { /* ci >= 0, cq < 0 */ \
566 if (-cq < ci) { \
567 v = ci - (cq >> 1); \
568 } else { \
569 v = -cq + (ci >> 1); \
570 } \
571 } else { /* ci >= 0, cq >= 0 */ \
572 if (cq < ci) { \
573 v = ci + (cq >> 1); \
574 } else { \
575 v = cq + (ci >> 1); \
576 } \
577 } \
578 } \
579 }
580
581 switch(Demod.state) {
582 case DEMOD_UNSYNCD:
583 CHECK_FOR_SUBCARRIER();
584 if(v > SUBCARRIER_DETECT_THRESHOLD) { // subcarrier detected
585 Demod.state = DEMOD_PHASE_REF_TRAINING;
586 Demod.sumI = ci;
587 Demod.sumQ = cq;
588 Demod.posCount = 1;
589 }
590 break;
591
592 case DEMOD_PHASE_REF_TRAINING:
593 if(Demod.posCount < 8) {
594 CHECK_FOR_SUBCARRIER();
595 if (v > SUBCARRIER_DETECT_THRESHOLD) {
596 // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
597 // note: synchronization time > 80 1/fs
598 Demod.sumI += ci;
599 Demod.sumQ += cq;
600 Demod.posCount++;
601 } else { // subcarrier lost
602 Demod.state = DEMOD_UNSYNCD;
603 }
604 } else {
605 Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
606 }
607 break;
608
609 case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
610 MAKE_SOFT_DECISION();
611 if(v < 0) { // logic '0' detected
612 Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
613 Demod.posCount = 0; // start of SOF sequence
614 } else {
615 if(Demod.posCount > 200/4) { // maximum length of TR1 = 200 1/fs
616 Demod.state = DEMOD_UNSYNCD;
617 }
618 }
619 Demod.posCount++;
620 break;
621
622 case DEMOD_GOT_FALLING_EDGE_OF_SOF:
623 Demod.posCount++;
624 MAKE_SOFT_DECISION();
625 if(v > 0) {
626 if(Demod.posCount < 9*2) { // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
627 Demod.state = DEMOD_UNSYNCD;
628 } else {
629 LED_C_ON(); // Got SOF
630 Demod.state = DEMOD_AWAITING_START_BIT;
631 Demod.posCount = 0;
632 Demod.len = 0;
633 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
634 Demod.metricN = 0;
635 Demod.metric = 0;
636 */
637 }
638 } else {
639 if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)
640 Demod.state = DEMOD_UNSYNCD;
641 LED_C_OFF();
642 }
643 }
644 break;
645
646 case DEMOD_AWAITING_START_BIT:
647 Demod.posCount++;
648 MAKE_SOFT_DECISION();
649 if(v > 0) {
650 if(Demod.posCount > 3*2) { // max 19us between characters = 16 1/fs, max 3 etu after low phase of SOF = 24 1/fs
651 Demod.state = DEMOD_UNSYNCD;
652 LED_C_OFF();
653 }
654 } else { // start bit detected
655 Demod.bitCount = 0;
656 Demod.posCount = 1; // this was the first half
657 Demod.thisBit = v;
658 Demod.shiftReg = 0;
659 Demod.state = DEMOD_RECEIVING_DATA;
660 }
661 break;
662
663 case DEMOD_RECEIVING_DATA:
664 MAKE_SOFT_DECISION();
665 if(Demod.posCount == 0) { // first half of bit
666 Demod.thisBit = v;
667 Demod.posCount = 1;
668 } else { // second half of bit
669 Demod.thisBit += v;
670
671 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
672 if(Demod.thisBit > 0) {
673 Demod.metric += Demod.thisBit;
674 } else {
675 Demod.metric -= Demod.thisBit;
676 }
677 (Demod.metricN)++;
678 */
679
680 Demod.shiftReg >>= 1;
681 if(Demod.thisBit > 0) { // logic '1'
682 Demod.shiftReg |= 0x200;
683 }
684
685 Demod.bitCount++;
686 if(Demod.bitCount == 10) {
687 uint16_t s = Demod.shiftReg;
688 if((s & 0x200) && !(s & 0x001)) { // stop bit == '1', start bit == '0'
689 uint8_t b = (s >> 1);
690 Demod.output[Demod.len] = b;
691 Demod.len++;
692 Demod.state = DEMOD_AWAITING_START_BIT;
693 } else {
694 Demod.state = DEMOD_UNSYNCD;
695 LED_C_OFF();
696 if(s == 0x000) {
697 // This is EOF (start, stop and all data bits == '0'
698 return TRUE;
699 }
700 }
701 }
702 Demod.posCount = 0;
703 }
704 break;
705
706 default:
707 Demod.state = DEMOD_UNSYNCD;
708 LED_C_OFF();
709 break;
710 }
711
712 return FALSE;
713 }
714
715
716 static void DemodReset()
717 {
718 // Clear out the state of the "UART" that receives from the tag.
719 Demod.len = 0;
720 Demod.state = DEMOD_UNSYNCD;
721 Demod.posCount = 0;
722 memset(Demod.output, 0x00, MAX_FRAME_SIZE);
723 }
724
725
726 static void DemodInit(uint8_t *data)
727 {
728 Demod.output = data;
729 DemodReset();
730 }
731
732
733 /*
734 * Demodulate the samples we received from the tag, also log to tracebuffer
735 * quiet: set to 'TRUE' to disable debug output
736 */
737 static void GetSamplesFor14443bDemod(int n, bool quiet)
738 {
739 int max = 0;
740 bool gotFrame = FALSE;
741 int lastRxCounter, ci, cq, samples = 0;
742
743 // Allocate memory from BigBuf for some buffers
744 // free all previous allocations first
745 BigBuf_free();
746
747 // The response (tag -> reader) that we're receiving.
748 uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
749
750 // The DMA buffer, used to stream samples from the FPGA
751 int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
752
753 // Set up the demodulator for tag -> reader responses.
754 DemodInit(receivedResponse);
755
756 // Setup and start DMA.
757 FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
758
759 int8_t *upTo = dmaBuf;
760 lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
761
762 // Signal field is ON with the appropriate LED:
763 LED_D_ON();
764 // And put the FPGA in the appropriate mode
765 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
766
767 for(;;) {
768 int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
769 if(behindBy > max) max = behindBy;
770
771 while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1)) > 2) {
772 ci = upTo[0];
773 cq = upTo[1];
774 upTo += 2;
775 if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
776 upTo = dmaBuf;
777 AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
778 AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
779 }
780 lastRxCounter -= 2;
781 if(lastRxCounter <= 0) {
782 lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
783 }
784
785 samples += 2;
786
787 if(Handle14443bSamplesDemod(ci, cq)) {
788 gotFrame = TRUE;
789 break;
790 }
791 }
792
793 if(samples > n || gotFrame) {
794 break;
795 }
796 }
797
798 AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
799
800 if (!quiet) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Demod.len = %d, Demod.sumI = %d, Demod.sumQ = %d", max, samples, gotFrame, Demod.len, Demod.sumI, Demod.sumQ);
801 //Tracing
802 if (tracing && Demod.len > 0) {
803 uint8_t parity[MAX_PARITY_SIZE];
804 LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
805 }
806 }
807
808
809 //-----------------------------------------------------------------------------
810 // Transmit the command (to the tag) that was placed in ToSend[].
811 //-----------------------------------------------------------------------------
812 static void TransmitFor14443b(void)
813 {
814 int c;
815
816 FpgaSetupSsc();
817
818 while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
819 AT91C_BASE_SSC->SSC_THR = 0xff;
820 }
821
822 // Signal field is ON with the appropriate Red LED
823 LED_D_ON();
824 // Signal we are transmitting with the Green LED
825 LED_B_ON();
826 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
827
828 for(c = 0; c < 10;) {
829 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
830 AT91C_BASE_SSC->SSC_THR = 0xff;
831 c++;
832 }
833 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
834 volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
835 (void)r;
836 }
837 WDT_HIT();
838 }
839
840 c = 0;
841 for(;;) {
842 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
843 AT91C_BASE_SSC->SSC_THR = ToSend[c];
844 c++;
845 if(c >= ToSendMax) {
846 break;
847 }
848 }
849 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
850 volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
851 (void)r;
852 }
853 WDT_HIT();
854 }
855 LED_B_OFF(); // Finished sending
856 }
857
858
859 //-----------------------------------------------------------------------------
860 // Code a layer 2 command (string of octets, including CRC) into ToSend[],
861 // so that it is ready to transmit to the tag using TransmitFor14443b().
862 //-----------------------------------------------------------------------------
863 static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
864 {
865 int i, j;
866 uint8_t b;
867
868 ToSendReset();
869
870 // Establish initial reference level
871 for(i = 0; i < 40; i++) {
872 ToSendStuffBit(1);
873 }
874 // Send SOF
875 for(i = 0; i < 10; i++) {
876 ToSendStuffBit(0);
877 }
878
879 for(i = 0; i < len; i++) {
880 // Stop bits/EGT
881 ToSendStuffBit(1);
882 ToSendStuffBit(1);
883 // Start bit
884 ToSendStuffBit(0);
885 // Data bits
886 b = cmd[i];
887 for(j = 0; j < 8; j++) {
888 if(b & 1) {
889 ToSendStuffBit(1);
890 } else {
891 ToSendStuffBit(0);
892 }
893 b >>= 1;
894 }
895 }
896 // Send EOF
897 ToSendStuffBit(1);
898 for(i = 0; i < 10; i++) {
899 ToSendStuffBit(0);
900 }
901 for(i = 0; i < 8; i++) {
902 ToSendStuffBit(1);
903 }
904
905 // And then a little more, to make sure that the last character makes
906 // it out before we switch to rx mode.
907 for(i = 0; i < 24; i++) {
908 ToSendStuffBit(1);
909 }
910
911 // Convert from last character reference to length
912 ToSendMax++;
913 }
914
915
916 /**
917 Convenience function to encode, transmit and trace iso 14443b comms
918 **/
919 static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
920 {
921 CodeIso14443bAsReader(cmd, len);
922 TransmitFor14443b();
923 if (tracing) {
924 uint8_t parity[MAX_PARITY_SIZE];
925 LogTrace(cmd,len, 0, 0, parity, TRUE);
926 }
927 }
928
929
930 //-----------------------------------------------------------------------------
931 // Read a SRI512 ISO 14443B tag.
932 //
933 // SRI512 tags are just simple memory tags, here we're looking at making a dump
934 // of the contents of the memory. No anticollision algorithm is done, we assume
935 // we have a single tag in the field.
936 //
937 // I tried to be systematic and check every answer of the tag, every CRC, etc...
938 //-----------------------------------------------------------------------------
939 void ReadSTMemoryIso14443b(uint32_t dwLast)
940 {
941 uint8_t i = 0x00;
942
943 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
944 // Make sure that we start from off, since the tags are stateful;
945 // confusing things will happen if we don't reset them between reads.
946 LED_D_OFF();
947 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
948 SpinDelay(200);
949
950 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
951 FpgaSetupSsc();
952
953 // Now give it time to spin up.
954 // Signal field is on with the appropriate LED
955 LED_D_ON();
956 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
957 SpinDelay(200);
958
959 clear_trace();
960 set_tracing(TRUE);
961
962 // First command: wake up the tag using the INITIATE command
963 uint8_t cmd1[] = {0x06, 0x00, 0x97, 0x5b};
964 CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
965 GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
966
967 if (Demod.len == 0) {
968 DbpString("No response from tag");
969 return;
970 } else {
971 Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
972 Demod.output[0], Demod.output[1], Demod.output[2]);
973 }
974
975 // There is a response, SELECT the uid
976 DbpString("Now SELECT tag:");
977 cmd1[0] = 0x0E; // 0x0E is SELECT
978 cmd1[1] = Demod.output[0];
979 ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
980 CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
981 GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
982 if (Demod.len != 3) {
983 Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
984 return;
985 }
986 // Check the CRC of the answer:
987 ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
988 if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
989 DbpString("CRC Error reading select response.");
990 return;
991 }
992 // Check response from the tag: should be the same UID as the command we just sent:
993 if (cmd1[1] != Demod.output[0]) {
994 Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
995 return;
996 }
997
998 // Tag is now selected,
999 // First get the tag's UID:
1000 cmd1[0] = 0x0B;
1001 ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
1002 CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
1003 GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1004 if (Demod.len != 10) {
1005 Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
1006 return;
1007 }
1008 // The check the CRC of the answer (use cmd1 as temporary variable):
1009 ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
1010 if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
1011 Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
1012 (cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
1013 // Do not return;, let's go on... (we should retry, maybe ?)
1014 }
1015 Dbprintf("Tag UID (64 bits): %08x %08x",
1016 (Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
1017 (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
1018
1019 // Now loop to read all 16 blocks, address from 0 to last block
1020 Dbprintf("Tag memory dump, block 0 to %d", dwLast);
1021 cmd1[0] = 0x08;
1022 i = 0x00;
1023 dwLast++;
1024 for (;;) {
1025 if (i == dwLast) {
1026 DbpString("System area block (0xff):");
1027 i = 0xff;
1028 }
1029 cmd1[1] = i;
1030 ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
1031 CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
1032 GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1033 if (Demod.len != 6) { // Check if we got an answer from the tag
1034 DbpString("Expected 6 bytes from tag, got less...");
1035 return;
1036 }
1037 // The check the CRC of the answer (use cmd1 as temporary variable):
1038 ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
1039 if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
1040 Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
1041 (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
1042 // Do not return;, let's go on... (we should retry, maybe ?)
1043 }
1044 // Now print out the memory location:
1045 Dbprintf("Address=%02x, Contents=%08x, CRC=%04x", i,
1046 (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
1047 (Demod.output[4]<<8)+Demod.output[5]);
1048 if (i == 0xff) {
1049 break;
1050 }
1051 i++;
1052 }
1053 }
1054
1055
1056 //=============================================================================
1057 // Finally, the `sniffer' combines elements from both the reader and
1058 // simulated tag, to show both sides of the conversation.
1059 //=============================================================================
1060
1061 //-----------------------------------------------------------------------------
1062 // Record the sequence of commands sent by the reader to the tag, with
1063 // triggering so that we start recording at the point that the tag is moved
1064 // near the reader.
1065 //-----------------------------------------------------------------------------
1066 /*
1067 * Memory usage for this function, (within BigBuf)
1068 * Last Received command (reader->tag) - MAX_FRAME_SIZE
1069 * Last Received command (tag->reader) - MAX_FRAME_SIZE
1070 * DMA Buffer - ISO14443B_DMA_BUFFER_SIZE
1071 * Demodulated samples received - all the rest
1072 */
1073 void RAMFUNC SnoopIso14443b(void)
1074 {
1075 // We won't start recording the frames that we acquire until we trigger;
1076 // a good trigger condition to get started is probably when we see a
1077 // response from the tag.
1078 int triggered = TRUE; // TODO: set and evaluate trigger condition
1079
1080 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
1081 BigBuf_free();
1082
1083 clear_trace();
1084 set_tracing(TRUE);
1085
1086 // The DMA buffer, used to stream samples from the FPGA
1087 int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
1088 int lastRxCounter;
1089 int8_t *upTo;
1090 int ci, cq;
1091 int maxBehindBy = 0;
1092
1093 // Count of samples received so far, so that we can include timing
1094 // information in the trace buffer.
1095 int samples = 0;
1096
1097 DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
1098 UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
1099
1100 // Print some debug information about the buffer sizes
1101 Dbprintf("Snooping buffers initialized:");
1102 Dbprintf(" Trace: %i bytes", BigBuf_max_traceLen());
1103 Dbprintf(" Reader -> tag: %i bytes", MAX_FRAME_SIZE);
1104 Dbprintf(" tag -> Reader: %i bytes", MAX_FRAME_SIZE);
1105 Dbprintf(" DMA: %i bytes", ISO14443B_DMA_BUFFER_SIZE);
1106
1107 // Signal field is off, no reader signal, no tag signal
1108 LEDsoff();
1109
1110 // And put the FPGA in the appropriate mode
1111 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);
1112 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
1113
1114 // Setup for the DMA.
1115 FpgaSetupSsc();
1116 upTo = dmaBuf;
1117 lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
1118 FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
1119 uint8_t parity[MAX_PARITY_SIZE];
1120
1121 bool TagIsActive = FALSE;
1122 bool ReaderIsActive = FALSE;
1123
1124 // And now we loop, receiving samples.
1125 for(;;) {
1126 int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
1127 (ISO14443B_DMA_BUFFER_SIZE-1);
1128 if(behindBy > maxBehindBy) {
1129 maxBehindBy = behindBy;
1130 }
1131
1132 if(behindBy < 2) continue;
1133
1134 ci = upTo[0];
1135 cq = upTo[1];
1136 upTo += 2;
1137 lastRxCounter -= 2;
1138 if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
1139 upTo = dmaBuf;
1140 lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
1141 AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
1142 AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
1143 WDT_HIT();
1144 if(behindBy > (9*ISO14443B_DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
1145 Dbprintf("blew circular buffer! behindBy=%d", behindBy);
1146 break;
1147 }
1148 if(!tracing) {
1149 DbpString("Reached trace limit");
1150 break;
1151 }
1152 if(BUTTON_PRESS()) {
1153 DbpString("cancelled");
1154 break;
1155 }
1156 }
1157
1158 samples += 2;
1159
1160 if (!TagIsActive) { // no need to try decoding reader data if the tag is sending
1161 if(Handle14443bUartBit(ci & 0x01)) {
1162 if(triggered && tracing) {
1163 LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
1164 }
1165 /* And ready to receive another command. */
1166 UartReset();
1167 /* And also reset the demod code, which might have been */
1168 /* false-triggered by the commands from the reader. */
1169 DemodReset();
1170 }
1171 if(Handle14443bUartBit(cq & 0x01)) {
1172 if(triggered && tracing) {
1173 LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
1174 }
1175 /* And ready to receive another command. */
1176 UartReset();
1177 /* And also reset the demod code, which might have been */
1178 /* false-triggered by the commands from the reader. */
1179 DemodReset();
1180 }
1181 ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
1182 }
1183
1184 if(!ReaderIsActive) { // no need to try decoding tag data if the reader is sending - and we cannot afford the time
1185 if(Handle14443bSamplesDemod(ci | 0x01, cq | 0x01)) {
1186
1187 //Use samples as a time measurement
1188 if(tracing)
1189 {
1190 uint8_t parity[MAX_PARITY_SIZE];
1191 LogTrace(Demod.output, Demod.len, samples, samples, parity, FALSE);
1192 }
1193 triggered = TRUE;
1194
1195 // And ready to receive another response.
1196 DemodReset();
1197 }
1198 TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
1199 }
1200
1201 }
1202
1203 FpgaDisableSscDma();
1204 LEDsoff();
1205 AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
1206 DbpString("Snoop statistics:");
1207 Dbprintf(" Max behind by: %i", maxBehindBy);
1208 Dbprintf(" Uart State: %x", Uart.state);
1209 Dbprintf(" Uart ByteCnt: %i", Uart.byteCnt);
1210 Dbprintf(" Uart ByteCntMax: %i", Uart.byteCntMax);
1211 Dbprintf(" Trace length: %i", BigBuf_get_traceLen());
1212 }
1213
1214
1215 /*
1216 * Send raw command to tag ISO14443B
1217 * @Input
1218 * datalen len of buffer data
1219 * recv bool when true wait for data from tag and send to client
1220 * powerfield bool leave the field on when true
1221 * data buffer with byte to send
1222 *
1223 * @Output
1224 * none
1225 *
1226 */
1227 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
1228 {
1229 FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
1230 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
1231 FpgaSetupSsc();
1232
1233 if (datalen){
1234 set_tracing(TRUE);
1235
1236 CodeAndTransmit14443bAsReader(data, datalen);
1237
1238 if(recv) {
1239 GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1240 uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
1241 cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
1242 }
1243 }
1244
1245 if(!powerfield) {
1246 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1247 LED_D_OFF();
1248 }
1249 }
1250
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