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Merge pull request #910 from pwpiwi/small_USB_response
[proxmark3-svn] / armsrc / hitag2.c
1 //-----------------------------------------------------------------------------
2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
3 // at your option, any later version. See the LICENSE.txt file for the text of
4 // the license.
5 //-----------------------------------------------------------------------------
6 // Hitag2 emulation (preliminary test version)
7 //
8 // (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
9 //-----------------------------------------------------------------------------
10 // Hitag2 complete rewrite of the code
11 // - Fixed modulation/encoding issues
12 // - Rewrote code for transponder emulation
13 // - Added snooping of transponder communication
14 // - Added reader functionality
15 //
16 // (c) 2012 Roel Verdult
17 //-----------------------------------------------------------------------------
18
19 #include "hitag2.h"
20
21 #include "proxmark3.h"
22 #include "usb_cdc.h"
23 #include "apps.h"
24 #include "util.h"
25 #include "hitag.h"
26 #include "string.h"
27 #include "BigBuf.h"
28 #include "fpgaloader.h"
29 #include "protocols.h"
30
31 static bool bQuiet;
32
33 static bool bCrypto;
34 static bool bAuthenticating;
35 static bool bPwd;
36 static bool bSuccessful;
37
38
39
40 struct hitag2_tag {
41 uint32_t uid;
42 enum {
43 TAG_STATE_RESET = 0x01, // Just powered up, awaiting GetSnr
44 TAG_STATE_ACTIVATING = 0x02 , // In activation phase (password mode), sent UID, awaiting reader password
45 TAG_STATE_ACTIVATED = 0x03, // Activation complete, awaiting read/write commands
46 TAG_STATE_WRITING = 0x04, // In write command, awaiting sector contents to be written
47 } state;
48 unsigned int active_sector;
49 uint8_t crypto_active;
50 uint64_t cs;
51 uint8_t sectors[12][4];
52 };
53
54 static struct hitag2_tag tag = {
55 .state = TAG_STATE_RESET,
56 .sectors = { // Password mode: | Crypto mode:
57 [0] = { 0x02, 0x4e, 0x02, 0x20}, // UID | UID
58 [1] = { 0x4d, 0x49, 0x4b, 0x52}, // Password RWD | 32 bit LSB key
59 [2] = { 0x20, 0xf0, 0x4f, 0x4e}, // Reserved | 16 bit MSB key, 16 bit reserved
60 [3] = { 0x0e, 0xaa, 0x48, 0x54}, // Configuration, password TAG | Configuration, password TAG
61 [4] = { 0x46, 0x5f, 0x4f, 0x4b}, // Data: F_OK
62 [5] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
63 [6] = { 0xaa, 0xaa, 0xaa, 0xaa}, // Data: ....
64 [7] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
65 [8] = { 0x00, 0x00, 0x00, 0x00}, // RSK Low
66 [9] = { 0x00, 0x00, 0x00, 0x00}, // RSK High
67 [10] = { 0x00, 0x00, 0x00, 0x00}, // RCF
68 [11] = { 0x00, 0x00, 0x00, 0x00}, // SYNC
69 },
70 };
71
72 static enum {
73 WRITE_STATE_START = 0x0,
74 WRITE_STATE_PAGENUM_WRITTEN,
75 WRITE_STATE_PROG
76 } writestate;
77
78
79 // ToDo: define a meaningful maximum size for auth_table. The bigger this is, the lower will be the available memory for traces.
80 // Historically it used to be FREE_BUFFER_SIZE, which was 2744.
81 #define AUTH_TABLE_LENGTH 2744
82 static uint8_t *auth_table;
83 static size_t auth_table_pos = 0;
84 static size_t auth_table_len = AUTH_TABLE_LENGTH;
85
86 static uint8_t password[4];
87 static uint8_t NrAr[8];
88 static uint8_t key[8];
89 static uint8_t writedata[4];
90 static uint64_t cipher_state;
91
92 /* Following is a modified version of cryptolib.com/ciphers/hitag2/ */
93 // Software optimized 48-bit Philips/NXP Mifare Hitag2 PCF7936/46/47/52 stream cipher algorithm by I.C. Wiener 2006-2007.
94 // For educational purposes only.
95 // No warranties or guarantees of any kind.
96 // This code is released into the public domain by its author.
97
98 // Single bit Hitag2 functions:
99
100 #define i4(x,a,b,c,d) ((uint32_t)((((x)>>(a))&1)+(((x)>>(b))&1)*2+(((x)>>(c))&1)*4+(((x)>>(d))&1)*8))
101
102 static const uint32_t ht2_f4a = 0x2C79; // 0010 1100 0111 1001
103 static const uint32_t ht2_f4b = 0x6671; // 0110 0110 0111 0001
104 static const uint32_t ht2_f5c = 0x7907287B; // 0111 1001 0000 0111 0010 1000 0111 1011
105
106 static uint32_t _f20(const uint64_t x) {
107 uint32_t i5;
108
109 i5 = ((ht2_f4a >> i4(x, 1, 2, 4, 5)) & 1) * 1
110 + ((ht2_f4b >> i4(x, 7,11,13,14)) & 1) * 2
111 + ((ht2_f4b >> i4(x,16,20,22,25)) & 1) * 4
112 + ((ht2_f4b >> i4(x,27,28,30,32)) & 1) * 8
113 + ((ht2_f4a >> i4(x,33,42,43,45)) & 1) * 16;
114
115 return (ht2_f5c >> i5) & 1;
116 }
117
118 static uint64_t _hitag2_init(const uint64_t key, const uint32_t serial, const uint32_t IV) {
119 uint32_t i;
120 uint64_t x = ((key & 0xFFFF) << 32) + serial;
121
122 for (i = 0; i < 32; i++) {
123 x >>= 1;
124 x += (uint64_t)(_f20(x) ^ (((IV >> i) ^ (key >> (i+16))) & 1)) << 47;
125 }
126 return x;
127 }
128
129 static uint64_t _hitag2_round(uint64_t *state) {
130 uint64_t x = *state;
131
132 x = (x >> 1) +
133 ((((x >> 0) ^ (x >> 2) ^ (x >> 3) ^ (x >> 6)
134 ^ (x >> 7) ^ (x >> 8) ^ (x >> 16) ^ (x >> 22)
135 ^ (x >> 23) ^ (x >> 26) ^ (x >> 30) ^ (x >> 41)
136 ^ (x >> 42) ^ (x >> 43) ^ (x >> 46) ^ (x >> 47)) & 1) << 47);
137
138 *state = x;
139 return _f20(x);
140 }
141
142 static uint32_t _hitag2_byte(uint64_t *x) {
143 uint32_t i, c;
144 for (i = 0, c = 0; i < 8; i++) {
145 c += (uint32_t) _hitag2_round(x) << (i^7);
146 }
147 return c;
148 }
149
150 static int hitag2_reset(void) {
151 tag.state = TAG_STATE_RESET;
152 tag.crypto_active = 0;
153 return 0;
154 }
155
156 static int hitag2_init(void) {
157 hitag2_reset();
158 return 0;
159 }
160
161 static void hitag2_cipher_reset(struct hitag2_tag *tag, const uint8_t *iv) {
162 uint64_t key = ((uint64_t)tag->sectors[2][2]) |
163 ((uint64_t)tag->sectors[2][3] << 8) |
164 ((uint64_t)tag->sectors[1][0] << 16) |
165 ((uint64_t)tag->sectors[1][1] << 24) |
166 ((uint64_t)tag->sectors[1][2] << 32) |
167 ((uint64_t)tag->sectors[1][3] << 40);
168 uint32_t uid = ((uint32_t)tag->sectors[0][0]) |
169 ((uint32_t)tag->sectors[0][1] << 8) |
170 ((uint32_t)tag->sectors[0][2] << 16) |
171 ((uint32_t)tag->sectors[0][3] << 24);
172 uint32_t iv_ = (((uint32_t)(iv[0]))) |
173 (((uint32_t)(iv[1])) << 8) |
174 (((uint32_t)(iv[2])) << 16) |
175 (((uint32_t)(iv[3])) << 24);
176 tag->cs = _hitag2_init(REV64(key), REV32(uid), REV32(iv_));
177 }
178
179 static int hitag2_cipher_authenticate(uint64_t *cs, const uint8_t *authenticator_is) {
180 uint8_t authenticator_should[4];
181 authenticator_should[0] = ~_hitag2_byte(cs);
182 authenticator_should[1] = ~_hitag2_byte(cs);
183 authenticator_should[2] = ~_hitag2_byte(cs);
184 authenticator_should[3] = ~_hitag2_byte(cs);
185 return (memcmp(authenticator_should, authenticator_is, 4) == 0);
186 }
187
188 static int hitag2_cipher_transcrypt(uint64_t *cs, uint8_t *data, unsigned int bytes, unsigned int bits) {
189 int i;
190 for (i = 0; i < bytes; i++) data[i] ^= _hitag2_byte(cs);
191 for (i = 0; i < bits; i++) data[bytes] ^= _hitag2_round(cs) << (7-i);
192 return 0;
193 }
194
195 // Sam7s has several timers, we will use the source TIMER_CLOCK1 (aka AT91C_TC_CLKS_TIMER_DIV1_CLOCK)
196 // TIMER_CLOCK1 = MCK/2, MCK is running at 48 MHz, Timer is running at 48/2 = 24 MHz
197 // Hitag units (T0) have duration of 8 microseconds (us), which is 1/125000 per second (carrier)
198 // T0 = TIMER_CLOCK1 / 125000 = 192
199 #define T0 192
200
201 #define HITAG_FRAME_LEN 20
202 #define HITAG_T_STOP 36 /* T_EOF should be > 36 */
203 #define HITAG_T_LOW 8 /* T_LOW should be 4..10 */
204 #define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */
205 #define HITAG_T_1_MIN 25 /* T[1] should be 26..30 */
206 //#define HITAG_T_EOF 40 /* T_EOF should be > 36 */
207 #define HITAG_T_EOF 80 /* T_EOF should be > 36 */
208 #define HITAG_T_WAIT_1 200 /* T_wresp should be 199..206 */
209 #define HITAG_T_WAIT_2 90 /* T_wresp should be 199..206 */
210 #define HITAG_T_WAIT_MAX 300 /* bit more than HITAG_T_WAIT_1 + HITAG_T_WAIT_2 */
211 #define HITAG_T_PROG 614
212
213 #define HITAG_T_TAG_ONE_HALF_PERIOD 10
214 #define HITAG_T_TAG_TWO_HALF_PERIOD 25
215 #define HITAG_T_TAG_THREE_HALF_PERIOD 41
216 #define HITAG_T_TAG_FOUR_HALF_PERIOD 57
217
218 #define HITAG_T_TAG_HALF_PERIOD 16
219 #define HITAG_T_TAG_FULL_PERIOD 32
220
221 #define HITAG_T_TAG_CAPTURE_ONE_HALF 13
222 #define HITAG_T_TAG_CAPTURE_TWO_HALF 25
223 #define HITAG_T_TAG_CAPTURE_THREE_HALF 41
224 #define HITAG_T_TAG_CAPTURE_FOUR_HALF 57
225
226 static void hitag_send_bit(int bit) {
227 LED_A_ON();
228 // Reset clock for the next bit
229 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
230
231 // Fixed modulation, earlier proxmark version used inverted signal
232 if (bit == 0) {
233 // Manchester: Unloaded, then loaded |__--|
234 LOW(GPIO_SSC_DOUT);
235 while (AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
236 HIGH(GPIO_SSC_DOUT);
237 while (AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
238 } else {
239 // Manchester: Loaded, then unloaded |--__|
240 HIGH(GPIO_SSC_DOUT);
241 while (AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
242 LOW(GPIO_SSC_DOUT);
243 while (AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
244 }
245 LED_A_OFF();
246 }
247
248 static void hitag_send_frame(const uint8_t *frame, size_t frame_len)
249 {
250 // Send start of frame
251 for(size_t i = 0; i < 5; i++) {
252 hitag_send_bit(1);
253 }
254
255 // Send the content of the frame
256 for (size_t i = 0; i < frame_len; i++) {
257 hitag_send_bit((frame[i/8] >> (7-(i%8))) & 0x01);
258 }
259
260 // Drop the modulation
261 LOW(GPIO_SSC_DOUT);
262 }
263
264 static void hitag2_handle_reader_command(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
265 uint8_t rx_air[HITAG_FRAME_LEN];
266
267 // Copy the (original) received frame how it is send over the air
268 memcpy(rx_air, rx, nbytes(rxlen));
269
270 if (tag.crypto_active) {
271 hitag2_cipher_transcrypt(&(tag.cs), rx, rxlen/8, rxlen%8);
272 }
273
274 // Reset the transmission frame length
275 *txlen = 0;
276
277 // Try to find out which command was send by selecting on length (in bits)
278 switch (rxlen) {
279 // Received 11000 from the reader, request for UID, send UID
280 case 05: {
281 // Always send over the air in the clear plaintext mode
282 if (rx_air[0] != HITAG2_START_AUTH) {
283 // Unknown frame ?
284 return;
285 }
286 *txlen = 32;
287 memcpy(tx, tag.sectors[0], 4);
288 tag.crypto_active = 0;
289 }
290 break;
291
292 // Read/Write command: ..xx x..y yy with yyy == ~xxx, xxx is sector number
293 case 10: {
294 unsigned int sector = (~( ((rx[0]<<2) & 0x04) | ((rx[1]>>6) & 0x03) ) & 0x07);
295 // Verify complement of sector index
296 if (sector != ((rx[0]>>3) & 0x07)) {
297 //DbpString("Transmission error (read/write)");
298 return;
299 }
300
301 switch (rx[0] & 0xC6) {
302 // Read command: 11xx x00y
303 case HITAG2_READ_PAGE:
304 memcpy(tx, tag.sectors[sector], 4);
305 *txlen = 32;
306 break;
307
308 // Inverted Read command: 01xx x10y
309 case HITAG2_READ_PAGE_INVERTED:
310 for (size_t i = 0; i < 4; i++) {
311 tx[i] = tag.sectors[sector][i] ^ 0xff;
312 }
313 *txlen = 32;
314 break;
315
316 // Write command: 10xx x01y
317 case HITAG2_WRITE_PAGE:
318 // Prepare write, acknowledge by repeating command
319 memcpy(tx, rx, nbytes(rxlen));
320 *txlen = rxlen;
321 tag.active_sector = sector;
322 tag.state = TAG_STATE_WRITING;
323 break;
324
325 // Unknown command
326 default:
327 Dbprintf("Unknown command: %02x %02x", rx[0], rx[1]);
328 return;
329 break;
330 }
331 }
332 break;
333
334 // Writing data or Reader password
335 case 32: {
336 if (tag.state == TAG_STATE_WRITING) {
337 // These are the sector contents to be written. We don't have to do anything else.
338 memcpy(tag.sectors[tag.active_sector], rx, nbytes(rxlen));
339 tag.state = TAG_STATE_RESET;
340 return;
341 } else {
342 // Received RWD password, respond with configuration and our password
343 if (memcmp(rx, tag.sectors[1], 4) != 0) {
344 DbpString("Reader password is wrong");
345 return;
346 }
347 *txlen = 32;
348 memcpy(tx, tag.sectors[3], 4);
349 }
350 }
351 break;
352
353 // Received RWD authentication challenge and respnse
354 case 64: {
355 // Store the authentication attempt
356 if (auth_table_len < (AUTH_TABLE_LENGTH-8)) {
357 memcpy(auth_table+auth_table_len, rx, 8);
358 auth_table_len += 8;
359 }
360
361 // Reset the cipher state
362 hitag2_cipher_reset(&tag, rx);
363 // Check if the authentication was correct
364 if (!hitag2_cipher_authenticate(&(tag.cs), rx+4)) {
365 // The reader failed to authenticate, do nothing
366 Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x Failed!", rx[0], rx[1], rx[2], rx[3], rx[4], rx[5], rx[6], rx[7]);
367 return;
368 }
369 // Succesful, but commented out reporting back to the Host, this may delay to much.
370 // Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x OK!",rx[0],rx[1],rx[2],rx[3],rx[4],rx[5],rx[6],rx[7]);
371
372 // Activate encryption algorithm for all further communication
373 tag.crypto_active = 1;
374
375 // Use the tag password as response
376 memcpy(tx, tag.sectors[3], 4);
377 *txlen = 32;
378 }
379 break;
380 }
381
382 // LogTraceHitag(rx, rxlen, 0, 0, false);
383 // LogTraceHitag(tx, *txlen, 0, 0, true);
384
385 if (tag.crypto_active) {
386 hitag2_cipher_transcrypt(&(tag.cs), tx, *txlen/8, *txlen%8);
387 }
388 }
389
390 static void hitag_reader_send_bit(int bit) {
391 LED_A_ON();
392 // Reset clock for the next bit
393 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
394
395 // Binary puls length modulation (BPLM) is used to encode the data stream
396 // This means that a transmission of a one takes longer than that of a zero
397
398 // Enable modulation, which means, drop the field
399 HIGH(GPIO_SSC_DOUT);
400
401 // t_low = 4...10 carrier periods
402 while (AT91C_BASE_TC0->TC_CV < T0*6);
403
404 // Disable modulation, just activates the field again
405 LOW(GPIO_SSC_DOUT);
406
407 if (bit == 0) {
408 // Zero bit: |_-|, T[0] = 18...22 carrier periods
409 while (AT91C_BASE_TC0->TC_CV < T0*22);
410 } else {
411 // One bit: |_--|, T[1] = 26...32 carrier periods
412 while (AT91C_BASE_TC0->TC_CV < T0*28);
413 }
414 LED_A_OFF();
415 }
416
417
418 static void hitag_reader_send_frame(const uint8_t *frame, size_t frame_len)
419 {
420 // Send the content of the frame
421 for(size_t i = 0; i < frame_len; i++) {
422 hitag_reader_send_bit((frame[i/8] >> (7-(i%8))) & 0x01);
423 }
424 // Send EOF
425 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
426 // Enable modulation, which means, drop the field
427 HIGH(GPIO_SSC_DOUT);
428 // t_low = 4...10 carrier periods
429 while (AT91C_BASE_TC0->TC_CV < T0*6);
430 // Disable modulation, just activates the field again
431 LOW(GPIO_SSC_DOUT);
432 // t_stop > 36 carrier periods
433 while (AT91C_BASE_TC0->TC_CV < T0*36);
434 }
435
436 size_t blocknr;
437
438 //-----------------------------------------------------------------------------
439 // Hitag2 operations
440 //-----------------------------------------------------------------------------
441
442 static bool hitag2_write_page(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
443 switch (writestate) {
444 case WRITE_STATE_START:
445 tx[0] = HITAG2_WRITE_PAGE | (blocknr << 3) | ((blocknr^7) >> 2);
446 tx[1] = ((blocknr^7) << 6);
447 *txlen = 10;
448 writestate = WRITE_STATE_PAGENUM_WRITTEN;
449 break;
450 case WRITE_STATE_PAGENUM_WRITTEN:
451 // Check if page number was received correctly
452 if ((rxlen == 10)
453 && (rx[0] == (HITAG2_WRITE_PAGE | (blocknr << 3) | ((blocknr^7) >> 2)))
454 && (rx[1] == (((blocknr & 0x3) ^ 0x3) << 6))) {
455 *txlen = 32;
456 memset(tx, 0, HITAG_FRAME_LEN);
457 memcpy(tx, writedata, 4);
458 writestate = WRITE_STATE_PROG;
459 } else {
460 Dbprintf("hitag2_write_page: Page number was not received correctly: rxlen=%d rx=%02x%02x%02x%02x",
461 rxlen, rx[0], rx[1], rx[2], rx[3]);
462 bSuccessful = false;
463 return false;
464 }
465 break;
466 case WRITE_STATE_PROG:
467 if (rxlen == 0) {
468 bSuccessful = true;
469 } else {
470 bSuccessful = false;
471 Dbprintf("hitag2_write_page: unexpected rx data (%d) after page write", rxlen);
472 }
473 return false;
474 default:
475 DbpString("hitag2_write_page: Unknown state %d");
476 bSuccessful = false;
477 return false;
478 }
479
480 return true;
481 }
482
483 static bool hitag2_password(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool write) {
484 // Reset the transmission frame length
485 *txlen = 0;
486
487 if (bPwd && !bAuthenticating && write) {
488 if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
489 return false;
490 }
491 } else {
492 // Try to find out which command was send by selecting on length (in bits)
493 switch (rxlen) {
494 // No answer, try to resurrect
495 case 0: {
496 // Stop if there is no answer (after sending password)
497 if (bPwd) {
498 DbpString("Password failed!");
499 return false;
500 }
501 tx[0] = HITAG2_START_AUTH;
502 *txlen = 5;
503 }
504 break;
505
506 // Received UID, tag password
507 case 32: {
508 if (!bPwd) {
509 bPwd = true;
510 bAuthenticating = true;
511 memcpy(tx, password, 4);
512 *txlen = 32;
513 } else {
514 if (bAuthenticating) {
515 bAuthenticating = false;
516 if (write) {
517 if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
518 return false;
519 }
520 break;
521 }
522 } else {
523 memcpy(tag.sectors[blocknr], rx, 4);
524 blocknr++;
525 }
526
527 if (blocknr > 7) {
528 DbpString("Read successful!");
529 bSuccessful = true;
530 return false;
531 }
532 tx[0] = HITAG2_READ_PAGE | (blocknr << 3) | ((blocknr^7) >> 2);
533 tx[1] = ((blocknr^7) << 6);
534 *txlen = 10;
535 }
536 }
537 break;
538
539 // Unexpected response
540 default: {
541 Dbprintf("Unknown frame length: %d", rxlen);
542 return false;
543 }
544 break;
545 }
546 }
547
548 return true;
549 }
550
551 static bool hitag2_crypto(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen, bool write) {
552 // Reset the transmission frame length
553 *txlen = 0;
554
555 if (bCrypto) {
556 hitag2_cipher_transcrypt(&cipher_state, rx, rxlen/8, rxlen%8);
557 }
558
559 if (bCrypto && !bAuthenticating && write) {
560 if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
561 return false;
562 }
563 } else {
564
565 // Try to find out which command was send by selecting on length (in bits)
566 switch (rxlen) {
567 // No answer, try to resurrect
568 case 0: {
569 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
570 if (bCrypto) {
571 // Failed during authentication
572 if (bAuthenticating) {
573 DbpString("Authentication failed!");
574 return false;
575 } else {
576 // Failed reading a block, could be (read/write) locked, skip block and re-authenticate
577 if (blocknr == 1) {
578 // Write the low part of the key in memory
579 memcpy(tag.sectors[1], key+2, 4);
580 } else if (blocknr == 2) {
581 // Write the high part of the key in memory
582 tag.sectors[2][0] = 0x00;
583 tag.sectors[2][1] = 0x00;
584 tag.sectors[2][2] = key[0];
585 tag.sectors[2][3] = key[1];
586 } else {
587 // Just put zero's in the memory (of the unreadable block)
588 memset(tag.sectors[blocknr], 0x00, 4);
589 }
590 blocknr++;
591 bCrypto = false;
592 }
593 } else {
594 tx[0] = HITAG2_START_AUTH;
595 *txlen = 5;
596 }
597 break;
598 }
599 // Received UID, crypto tag answer
600 case 32: {
601 if (!bCrypto) {
602 uint64_t ui64key = key[0] | ((uint64_t)key[1]) << 8 | ((uint64_t)key[2]) << 16 | ((uint64_t)key[3]) << 24 | ((uint64_t)key[4]) << 32 | ((uint64_t)key[5]) << 40;
603 uint32_t ui32uid = rx[0] | ((uint32_t)rx[1]) << 8 | ((uint32_t)rx[2]) << 16 | ((uint32_t)rx[3]) << 24;
604 Dbprintf("hitag2_crypto: key=0x%x%x uid=0x%x", (uint32_t) ((REV64(ui64key)) >> 32), (uint32_t) ((REV64(ui64key)) & 0xffffffff), REV32(ui32uid));
605 cipher_state = _hitag2_init(REV64(ui64key), REV32(ui32uid), 0);
606 memset(tx, 0x00, 4);
607 memset(tx+4, 0xff, 4);
608 hitag2_cipher_transcrypt(&cipher_state, tx+4, 4, 0);
609 *txlen = 64;
610 bCrypto = true;
611 bAuthenticating = true;
612 } else {
613 // Check if we received answer tag (at)
614 if (bAuthenticating) {
615 bAuthenticating = false;
616 if (write) {
617 if (!hitag2_write_page(rx, rxlen, tx, txlen)) {
618 return false;
619 }
620 break;
621 }
622 }
623 // stage 2+, got data block
624 else {
625 // Store the received block
626 memcpy(tag.sectors[blocknr], rx, 4);
627 blocknr++;
628 }
629 if (blocknr > 7) {
630 DbpString("Read successful!");
631 bSuccessful = true;
632 return false;
633 } else {
634 tx[0] = HITAG2_READ_PAGE | (blocknr << 3) | ((blocknr ^ 7) >> 2);
635 tx[1] = ((blocknr ^ 7) << 6);
636 *txlen = 10;
637 }
638 }
639 }
640 break;
641
642 // Unexpected response
643 default: {
644 Dbprintf("Unknown frame length: %d",rxlen);
645 return false;
646 }
647 break;
648 }
649 }
650
651 if (bCrypto) {
652 // We have to return now to avoid double encryption
653 if (!bAuthenticating) {
654 hitag2_cipher_transcrypt(&cipher_state, tx, *txlen/8, *txlen%8);
655 }
656 }
657
658 return true;
659 }
660
661 static bool hitag2_authenticate(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
662 // Reset the transmission frame length
663 *txlen = 0;
664
665 // Try to find out which command was send by selecting on length (in bits)
666 switch (rxlen) {
667 // No answer, try to resurrect
668 case 0: {
669 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
670 if (bCrypto) {
671 DbpString("Authentication failed!");
672 return false;
673 }
674 tx[0] = HITAG2_START_AUTH;
675 *txlen = 5;
676 }
677 break;
678
679 // Received UID, crypto tag answer
680 case 32: {
681 if (!bCrypto) {
682 memcpy(tx, NrAr, 8);
683 *txlen = 64;
684 bCrypto = true;
685 } else {
686 DbpString("Authentication successful!");
687 // We are done... for now
688 return false;
689 }
690 }
691 break;
692
693 // Unexpected response
694 default: {
695 Dbprintf("Unknown frame length: %d",rxlen);
696 return false;
697 }
698 break;
699 }
700
701 return true;
702 }
703
704 static bool hitag2_test_auth_attempts(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
705
706 // Reset the transmission frame length
707 *txlen = 0;
708
709 // Try to find out which command was send by selecting on length (in bits)
710 switch (rxlen) {
711 // No answer, try to resurrect
712 case 0: {
713 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
714 if (bCrypto) {
715 Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x Failed, removed entry!", NrAr[0], NrAr[1], NrAr[2], NrAr[3], NrAr[4], NrAr[5], NrAr[6], NrAr[7]);
716
717 // Removing failed entry from authentiations table
718 memcpy(auth_table+auth_table_pos, auth_table+auth_table_pos+8, 8);
719 auth_table_len -= 8;
720
721 // Return if we reached the end of the authentications table
722 bCrypto = false;
723 if (auth_table_pos == auth_table_len) {
724 return false;
725 }
726
727 // Copy the next authentication attempt in row (at the same position, b/c we removed last failed entry)
728 memcpy(NrAr, auth_table+auth_table_pos, 8);
729 }
730 tx[0] = HITAG2_START_AUTH;
731 *txlen = 5;
732 }
733 break;
734
735 // Received UID, crypto tag answer, or read block response
736 case 32: {
737 if (!bCrypto) {
738 *txlen = 64;
739 memcpy(tx, NrAr, 8);
740 bCrypto = true;
741 } else {
742 Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x OK", NrAr[0], NrAr[1], NrAr[2], NrAr[3], NrAr[4], NrAr[5], NrAr[6], NrAr[7]);
743 bCrypto = false;
744 if ((auth_table_pos+8) == auth_table_len) {
745 return false;
746 }
747 auth_table_pos += 8;
748 memcpy(NrAr, auth_table+auth_table_pos, 8);
749 }
750 }
751 break;
752
753 default: {
754 Dbprintf("Unknown frame length: %d",rxlen);
755 return false;
756 }
757 break;
758 }
759
760 return true;
761 }
762
763 static bool hitag2_read_uid(uint8_t *rx, const size_t rxlen, uint8_t *tx, size_t *txlen) {
764 // Reset the transmission frame length
765 *txlen = 0;
766
767 // Try to find out which command was send by selecting on length (in bits)
768 switch (rxlen) {
769 // No answer, try to resurrect
770 case 0: {
771 // Just starting or if there is no answer
772 tx[0] = HITAG2_START_AUTH;
773 *txlen = 5;
774 }
775 break;
776 // Received UID
777 case 32: {
778 // Check if we received answer tag (at)
779 if (bAuthenticating) {
780 bAuthenticating = false;
781 } else {
782 // Store the received block
783 memcpy(tag.sectors[blocknr], rx, 4);
784 blocknr++;
785 }
786 if (blocknr > 0) {
787 //DbpString("Read successful!");
788 bSuccessful = true;
789 return false;
790 }
791 }
792 break;
793 // Unexpected response
794 default: {
795 Dbprintf("Unknown frame length: %d",rxlen);
796 return false;
797 }
798 break;
799 }
800 return true;
801 }
802
803 void SnoopHitag(uint32_t type) {
804 // int frame_count;
805 int response;
806 int overflow;
807 bool rising_edge;
808 bool reader_frame;
809 int lastbit;
810 bool bSkip;
811 int tag_sof;
812 uint8_t rx[HITAG_FRAME_LEN] = {0};
813 size_t rxlen = 0;
814
815 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
816
817 // Clean up trace and prepare it for storing frames
818 set_tracing(true);
819 clear_trace();
820
821 auth_table_len = 0;
822 auth_table_pos = 0;
823
824 BigBuf_free();
825 auth_table = (uint8_t *)BigBuf_malloc(AUTH_TABLE_LENGTH);
826 memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
827
828 DbpString("Starting Hitag2 snoop");
829 LED_D_ON();
830
831 // Set up eavesdropping mode, frequency divisor which will drive the FPGA
832 // and analog mux selection.
833 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_TOGGLE_MODE);
834 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
835 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
836
837 // Configure output pin that is connected to the FPGA (for modulating)
838 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
839 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
840
841 // Disable modulation, we are going to eavesdrop, not modulate ;)
842 LOW(GPIO_SSC_DOUT);
843
844 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
845 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
846 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
847
848 // Disable timer during configuration
849 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
850
851 // TC1: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
852 // external trigger rising edge, load RA on rising edge of TIOA.
853 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_BOTH | AT91C_TC_ABETRG | AT91C_TC_LDRA_BOTH;
854
855 // Enable and reset counter
856 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
857
858 // Reset the received frame, frame count and timing info
859 // frame_count = 0;
860 response = 0;
861 overflow = 0;
862 reader_frame = false;
863 lastbit = 1;
864 bSkip = true;
865 tag_sof = 4;
866
867 while (!BUTTON_PRESS()) {
868 // Watchdog hit
869 WDT_HIT();
870
871 // Receive frame, watch for at most T0*EOF periods
872 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_EOF) {
873 // Check if rising edge in modulation is detected
874 if (AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
875 // Retrieve the new timing values
876 int ra = (AT91C_BASE_TC1->TC_RA/T0);
877
878 // Find out if we are dealing with a rising or falling edge
879 rising_edge = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME) > 0;
880
881 // Shorter periods will only happen with reader frames
882 if (!reader_frame && rising_edge && ra < HITAG_T_TAG_CAPTURE_ONE_HALF) {
883 // Switch from tag to reader capture
884 LED_C_OFF();
885 reader_frame = true;
886 memset(rx, 0x00, sizeof(rx));
887 rxlen = 0;
888 }
889
890 // Only handle if reader frame and rising edge, or tag frame and falling edge
891 if (reader_frame != rising_edge) {
892 overflow += ra;
893 continue;
894 }
895
896 // Add the buffered timing values of earlier captured edges which were skipped
897 ra += overflow;
898 overflow = 0;
899
900 if (reader_frame) {
901 LED_B_ON();
902 // Capture reader frame
903 if (ra >= HITAG_T_STOP) {
904 if (rxlen != 0) {
905 //DbpString("wierd0?");
906 }
907 // Capture the T0 periods that have passed since last communication or field drop (reset)
908 response = (ra - HITAG_T_LOW);
909 } else if (ra >= HITAG_T_1_MIN) {
910 // '1' bit
911 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
912 rxlen++;
913 } else if (ra >= HITAG_T_0_MIN) {
914 // '0' bit
915 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
916 rxlen++;
917 } else {
918 // Ignore wierd value, is to small to mean anything
919 }
920 } else {
921 LED_C_ON();
922 // Capture tag frame (manchester decoding using only falling edges)
923 if (ra >= HITAG_T_EOF) {
924 if (rxlen != 0) {
925 //DbpString("wierd1?");
926 }
927 // Capture the T0 periods that have passed since last communication or field drop (reset)
928 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
929 response = ra - HITAG_T_TAG_HALF_PERIOD;
930 } else if (ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
931 // Manchester coding example |-_|_-|-_| (101)
932 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
933 rxlen++;
934 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
935 rxlen++;
936 } else if (ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
937 // Manchester coding example |_-|...|_-|-_| (0...01)
938 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
939 rxlen++;
940 // We have to skip this half period at start and add the 'one' the second time
941 if (!bSkip) {
942 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
943 rxlen++;
944 }
945 lastbit = !lastbit;
946 bSkip = !bSkip;
947 } else if (ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
948 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
949 if (tag_sof) {
950 // Ignore bits that are transmitted during SOF
951 tag_sof--;
952 } else {
953 // bit is same as last bit
954 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
955 rxlen++;
956 }
957 } else {
958 // Ignore wierd value, is to small to mean anything
959 }
960 }
961 }
962 }
963
964 // Check if frame was captured
965 if (rxlen > 0) {
966 // frame_count++;
967 if (!LogTraceHitag(rx, rxlen, response, 0, reader_frame)) {
968 DbpString("Trace full");
969 break;
970 }
971
972 // Check if we recognize a valid authentication attempt
973 if (nbytes(rxlen) == 8) {
974 // Store the authentication attempt
975 if (auth_table_len < (AUTH_TABLE_LENGTH-8)) {
976 memcpy(auth_table+auth_table_len,rx,8);
977 auth_table_len += 8;
978 }
979 }
980
981 // Reset the received frame and response timing info
982 memset(rx, 0x00, sizeof(rx));
983 response = 0;
984 reader_frame = false;
985 lastbit = 1;
986 bSkip = true;
987 tag_sof = 4;
988 overflow = 0;
989
990 LED_B_OFF();
991 LED_C_OFF();
992 } else {
993 // Save the timer overflow, will be 0 when frame was received
994 overflow += (AT91C_BASE_TC1->TC_CV/T0);
995 }
996 // Reset the frame length
997 rxlen = 0;
998 // Reset the timer to restart while-loop that receives frames
999 AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
1000 }
1001 LED_A_ON();
1002 LED_B_OFF();
1003 LED_C_OFF();
1004 LED_D_OFF();
1005 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1006 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1007 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1008 LED_A_OFF();
1009
1010 // Dbprintf("frame received: %d",frame_count);
1011 // Dbprintf("Authentication Attempts: %d",(auth_table_len/8));
1012 // DbpString("All done");
1013 }
1014
1015 void SimulateHitagTag(bool tag_mem_supplied, uint8_t *data) {
1016 // int frame_count;
1017 int response;
1018 int overflow;
1019 uint8_t rx[HITAG_FRAME_LEN];
1020 size_t rxlen = 0;
1021 uint8_t tx[HITAG_FRAME_LEN];
1022 size_t txlen = 0;
1023 bool bQuitTraceFull = false;
1024 bQuiet = false;
1025
1026 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
1027
1028 // Clean up trace and prepare it for storing frames
1029 set_tracing(true);
1030 clear_trace();
1031
1032 auth_table_len = 0;
1033 auth_table_pos = 0;
1034 uint8_t *auth_table;
1035 BigBuf_free();
1036 auth_table = BigBuf_malloc(AUTH_TABLE_LENGTH);
1037 memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
1038
1039 DbpString("Starting Hitag2 simulation");
1040 LED_D_ON();
1041 hitag2_init();
1042
1043 if (tag_mem_supplied) {
1044 DbpString("Loading hitag2 memory...");
1045 memcpy((uint8_t*)tag.sectors, data, 48);
1046 }
1047
1048 uint32_t block = 0;
1049 for (size_t i = 0; i < 12; i++) {
1050 for (size_t j = 0; j < 4; j++) {
1051 block <<= 8;
1052 block |= tag.sectors[i][j];
1053 }
1054 Dbprintf("| %d | %08x |", i, block);
1055 }
1056
1057 // Set up simulator mode, frequency divisor which will drive the FPGA
1058 // and analog mux selection.
1059 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
1060 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
1061 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
1062
1063 // Configure output pin that is connected to the FPGA (for modulating)
1064 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
1065 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
1066
1067 // Disable modulation at default, which means release resistance
1068 LOW(GPIO_SSC_DOUT);
1069
1070 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
1071 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
1072
1073 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
1074 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
1075 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
1076
1077 // Disable timer during configuration
1078 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1079 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1080
1081 // TC0: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), no triggers
1082 AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK;
1083
1084 // TC1: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
1085 // external trigger rising edge, load RA on rising edge of TIOA.
1086 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_RISING | AT91C_TC_ABETRG | AT91C_TC_LDRA_RISING;
1087
1088 // Reset the received frame, frame count and timing info
1089 memset(rx, 0x00, sizeof(rx));
1090 // frame_count = 0;
1091 response = 0;
1092 overflow = 0;
1093
1094 // Enable and reset counter
1095 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1096
1097 while (!BUTTON_PRESS()) {
1098 // Watchdog hit
1099 WDT_HIT();
1100
1101 // Receive frame, watch for at most T0*EOF periods
1102 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_EOF) {
1103 // Check if rising edge in modulation is detected
1104 if (AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
1105 // Retrieve the new timing values
1106 int ra = (AT91C_BASE_TC1->TC_RA/T0) + overflow;
1107 overflow = 0;
1108
1109 // Reset timer every frame, we have to capture the last edge for timing
1110 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1111
1112 LED_B_ON();
1113
1114 // Capture reader frame
1115 if (ra >= HITAG_T_STOP) {
1116 if (rxlen != 0) {
1117 //DbpString("wierd0?");
1118 }
1119 // Capture the T0 periods that have passed since last communication or field drop (reset)
1120 response = (ra - HITAG_T_LOW);
1121 } else if (ra >= HITAG_T_1_MIN) {
1122 // '1' bit
1123 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1124 rxlen++;
1125 } else if (ra >= HITAG_T_0_MIN) {
1126 // '0' bit
1127 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1128 rxlen++;
1129 } else {
1130 // Ignore wierd value, is to small to mean anything
1131 }
1132 }
1133 }
1134
1135 // Check if frame was captured
1136 if (rxlen > 4) {
1137 // frame_count++;
1138 if (!bQuiet) {
1139 if (!LogTraceHitag(rx, rxlen, response, 0, true)) {
1140 DbpString("Trace full");
1141 if (bQuitTraceFull) {
1142 break;
1143 } else {
1144 bQuiet = true;
1145 }
1146 }
1147 }
1148
1149 // Disable timer 1 with external trigger to avoid triggers during our own modulation
1150 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1151
1152 // Process the incoming frame (rx) and prepare the outgoing frame (tx)
1153 hitag2_handle_reader_command(rx, rxlen, tx, &txlen);
1154
1155 // Wait for HITAG_T_WAIT_1 carrier periods after the last reader bit,
1156 // not that since the clock counts since the rising edge, but T_Wait1 is
1157 // with respect to the falling edge, we need to wait actually (T_Wait1 - T_Low)
1158 // periods. The gap time T_Low varies (4..10). All timer values are in
1159 // terms of T0 units
1160 while (AT91C_BASE_TC0->TC_CV < T0*(HITAG_T_WAIT_1-HITAG_T_LOW));
1161
1162 // Send and store the tag answer (if there is any)
1163 if (txlen) {
1164 // Transmit the tag frame
1165 hitag_send_frame(tx, txlen);
1166 // Store the frame in the trace
1167 if (!bQuiet) {
1168 if (!LogTraceHitag(tx, txlen, 0, 0, false)) {
1169 DbpString("Trace full");
1170 if (bQuitTraceFull) {
1171 break;
1172 } else {
1173 bQuiet = true;
1174 }
1175 }
1176 }
1177 }
1178
1179 // Reset the received frame and response timing info
1180 memset(rx, 0x00, sizeof(rx));
1181 response = 0;
1182
1183 // Enable and reset external trigger in timer for capturing future frames
1184 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1185 LED_B_OFF();
1186 }
1187 // Reset the frame length
1188 rxlen = 0;
1189 // Save the timer overflow, will be 0 when frame was received
1190 overflow += (AT91C_BASE_TC1->TC_CV/T0);
1191 // Reset the timer to restart while-loop that receives frames
1192 AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
1193 }
1194 LED_B_OFF();
1195 LED_D_OFF();
1196 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1197 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1198 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1199
1200 DbpString("Sim Stopped");
1201
1202 }
1203
1204 void ReaderHitag(hitag_function htf, hitag_data *htd) {
1205 // int frame_count;
1206 int response;
1207 uint8_t rx[HITAG_FRAME_LEN];
1208 size_t rxlen = 0;
1209 uint8_t txbuf[HITAG_FRAME_LEN];
1210 uint8_t *tx = txbuf;
1211 size_t txlen = 0;
1212 int lastbit;
1213 bool bSkip;
1214 int reset_sof;
1215 int tag_sof;
1216 int t_wait = HITAG_T_WAIT_MAX;
1217 bool bStop = false;
1218 bool bQuitTraceFull = false;
1219
1220 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
1221 // Reset the return status
1222 bSuccessful = false;
1223
1224 // Clean up trace and prepare it for storing frames
1225 set_tracing(true);
1226 clear_trace();
1227
1228 //DbpString("Starting Hitag reader family");
1229
1230 // Check configuration
1231 switch (htf) {
1232 case RHT2F_PASSWORD: {
1233 Dbprintf("List identifier in password mode");
1234 memcpy(password, htd->pwd.password, 4);
1235 blocknr = 0;
1236 bQuitTraceFull = false;
1237 bQuiet = false;
1238 bPwd = false;
1239 bAuthenticating = false;
1240 }
1241 break;
1242 case RHT2F_AUTHENTICATE: {
1243 DbpString("Authenticating using nr,ar pair:");
1244 memcpy(NrAr, htd->auth.NrAr, 8);
1245 Dbhexdump(8, NrAr, false);
1246 bQuiet = false;
1247 bCrypto = false;
1248 bAuthenticating = false;
1249 bQuitTraceFull = true;
1250 }
1251 break;
1252 case RHT2F_CRYPTO:
1253 {
1254 DbpString("Authenticating using key:");
1255 memcpy(key, htd->crypto.key, 6); //HACK; 4 or 6?? I read both in the code.
1256 Dbhexdump(6, key, false);
1257 blocknr = 0;
1258 bQuiet = false;
1259 bCrypto = false;
1260 bAuthenticating = false;
1261 bQuitTraceFull = true;
1262 }
1263 break;
1264 case RHT2F_TEST_AUTH_ATTEMPTS: {
1265 Dbprintf("Testing %d authentication attempts", (auth_table_len/8));
1266 auth_table_pos = 0;
1267 memcpy(NrAr, auth_table, 8);
1268 bQuitTraceFull = false;
1269 bQuiet = false;
1270 bCrypto = false;
1271 }
1272 break;
1273 case RHT2F_UID_ONLY: {
1274 blocknr = 0;
1275 bQuiet = false;
1276 bCrypto = false;
1277 bAuthenticating = false;
1278 bQuitTraceFull = true;
1279 }
1280 break;
1281 default: {
1282 Dbprintf("Error, unknown function: %d", htf);
1283 return;
1284 }
1285 break;
1286 }
1287
1288 LED_D_ON();
1289 hitag2_init();
1290
1291 // Configure output and enable pin that is connected to the FPGA (for modulating)
1292 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
1293 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
1294
1295 // Set fpga in edge detect with reader field, we can modulate as reader now
1296 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
1297
1298 // Set Frequency divisor which will drive the FPGA and analog mux selection
1299 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
1300 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
1301
1302 // Disable modulation at default, which means enable the field
1303 LOW(GPIO_SSC_DOUT);
1304
1305 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
1306 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
1307
1308 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the tag frames
1309 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
1310 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
1311
1312 // Disable timer during configuration
1313 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1314 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1315
1316 // TC0: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), no triggers
1317 AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK;
1318
1319 // TC1: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
1320 // external trigger rising edge, load RA on falling edge of TIOA.
1321 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_FALLING | AT91C_TC_ABETRG | AT91C_TC_LDRA_FALLING;
1322
1323 // Enable and reset counters
1324 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1325 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1326
1327 // Reset the received frame, frame count and timing info
1328 // frame_count = 0;
1329 response = 0;
1330 lastbit = 1;
1331
1332 // Tag specific configuration settings (sof, timings, etc.)
1333 if (htf < 10) {
1334 // hitagS settings
1335 reset_sof = 1;
1336 t_wait = 200;
1337 //DbpString("Configured for hitagS reader");
1338 } else if (htf < 20) {
1339 // hitag1 settings
1340 reset_sof = 1;
1341 t_wait = 200;
1342 //DbpString("Configured for hitag1 reader");
1343 } else if (htf < 30) {
1344 // hitag2 settings
1345 reset_sof = 4;
1346 t_wait = HITAG_T_WAIT_2;
1347 //DbpString("Configured for hitag2 reader");
1348 } else {
1349 Dbprintf("Error, unknown hitag reader type: %d", htf);
1350 goto out;
1351 }
1352
1353 // wait for tag to power up
1354 // t_PowerUp = 312,5 carrier periods
1355 while (AT91C_BASE_TC0->TC_CV < T0*(312-t_wait));
1356
1357 uint8_t attempt_count = 0;
1358 while (!bStop && !BUTTON_PRESS()) {
1359 WDT_HIT();
1360
1361 // Check if frame was captured and store it
1362 if (rxlen > 0) {
1363 // frame_count++;
1364 if (!bQuiet) {
1365 if (!LogTraceHitag(rx, rxlen, response, 0, false)) {
1366 DbpString("Trace full");
1367 if (bQuitTraceFull) {
1368 break;
1369 } else {
1370 bQuiet = true;
1371 }
1372 }
1373 }
1374 }
1375
1376 // By default reset the transmission buffer
1377 tx = txbuf;
1378 switch (htf) {
1379 case RHT2F_PASSWORD: {
1380 bStop = !hitag2_password(rx, rxlen, tx, &txlen, false);
1381 }
1382 break;
1383 case RHT2F_AUTHENTICATE: {
1384 bStop = !hitag2_authenticate(rx, rxlen, tx, &txlen);
1385 }
1386 break;
1387 case RHT2F_CRYPTO: {
1388 bStop = !hitag2_crypto(rx, rxlen, tx, &txlen, false);
1389 }
1390 break;
1391 case RHT2F_TEST_AUTH_ATTEMPTS: {
1392 bStop = !hitag2_test_auth_attempts(rx, rxlen, tx, &txlen);
1393 }
1394 break;
1395 case RHT2F_UID_ONLY: {
1396 bStop = !hitag2_read_uid(rx, rxlen, tx, &txlen);
1397 attempt_count++; //attempt 3 times to get uid then quit
1398 if (!bStop && attempt_count == 3)
1399 bStop = true;
1400 }
1401 break;
1402 default: {
1403 Dbprintf("Error, unknown function: %d", htf);
1404 goto out;
1405 }
1406 }
1407
1408 // Send and store the reader command
1409 // Disable timer 1 with external trigger to avoid triggers during our own modulation
1410 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1411
1412 // Wait for HITAG_T_WAIT_2 carrier periods after the last tag bit before transmitting,
1413 // Since the clock counts since the last falling edge, a 'one' means that the
1414 // falling edge occured halfway the period. with respect to this falling edge,
1415 // we need to wait (T_Wait2 + half_tag_period) when the last was a 'one'.
1416 // All timer values are in terms of T0 units
1417 while (AT91C_BASE_TC0->TC_CV < T0*(t_wait+(HITAG_T_TAG_HALF_PERIOD*lastbit)));
1418
1419 //Dbprintf("DEBUG: Sending reader frame");
1420
1421 // Transmit the reader frame
1422 hitag_reader_send_frame(tx, txlen);
1423
1424 // Enable and reset external trigger in timer for capturing future frames
1425 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1426
1427 // Add transmitted frame to total count
1428 if (txlen > 0) {
1429 // frame_count++;
1430 if (!bQuiet) {
1431 // Store the frame in the trace
1432 if (!LogTraceHitag(tx, txlen, HITAG_T_WAIT_2, 0, true)) {
1433 if (bQuitTraceFull) {
1434 break;
1435 } else {
1436 bQuiet = true;
1437 }
1438 }
1439 }
1440 }
1441
1442 // Reset values for receiving frames
1443 memset(rx, 0x00, sizeof(rx));
1444 rxlen = 0;
1445 lastbit = 1;
1446 bSkip = true;
1447 tag_sof = reset_sof;
1448 response = 0;
1449 //Dbprintf("DEBUG: Waiting to receive frame");
1450 uint32_t errorCount = 0;
1451
1452 // Receive frame, watch for at most T0*EOF periods
1453 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_WAIT_MAX) {
1454 // Check if falling edge in tag modulation is detected
1455 if (AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
1456 // Retrieve the new timing values
1457 int ra = (AT91C_BASE_TC1->TC_RA/T0);
1458
1459 // Reset timer every frame, we have to capture the last edge for timing
1460 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
1461
1462 LED_B_ON();
1463
1464 // Capture tag frame (manchester decoding using only falling edges)
1465 if (ra >= HITAG_T_EOF) {
1466 if (rxlen != 0) {
1467 //Dbprintf("DEBUG: Wierd1");
1468 }
1469 // Capture the T0 periods that have passed since last communication or field drop (reset)
1470 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
1471 response = ra - HITAG_T_TAG_HALF_PERIOD;
1472 } else if (ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
1473 // Manchester coding example |-_|_-|-_| (101)
1474
1475 //need to test to verify we don't exceed memory...
1476 //if ( ((rxlen+2) / 8) > HITAG_FRAME_LEN) {
1477 // break;
1478 //}
1479 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1480 rxlen++;
1481 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1482 rxlen++;
1483 } else if (ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
1484 // Manchester coding example |_-|...|_-|-_| (0...01)
1485
1486 //need to test to verify we don't exceed memory...
1487 //if ( ((rxlen+2) / 8) > HITAG_FRAME_LEN) {
1488 // break;
1489 //}
1490 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1491 rxlen++;
1492 // We have to skip this half period at start and add the 'one' the second time
1493 if (!bSkip) {
1494 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1495 rxlen++;
1496 }
1497 lastbit = !lastbit;
1498 bSkip = !bSkip;
1499 } else if (ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
1500 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
1501
1502 //need to test to verify we don't exceed memory...
1503 //if ( ((rxlen+2) / 8) > HITAG_FRAME_LEN) {
1504 // break;
1505 //}
1506 if (tag_sof) {
1507 // Ignore bits that are transmitted during SOF
1508 tag_sof--;
1509 } else {
1510 // bit is same as last bit
1511 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
1512 rxlen++;
1513 }
1514 } else {
1515 //Dbprintf("DEBUG: Wierd2");
1516 errorCount++;
1517 // Ignore wierd value, is to small to mean anything
1518 }
1519 }
1520 //if we saw over 100 wierd values break it probably isn't hitag...
1521 if (errorCount > 100) break;
1522 // We can break this loop if we received the last bit from a frame
1523 if (AT91C_BASE_TC1->TC_CV > T0*HITAG_T_EOF) {
1524 if (rxlen > 0) break;
1525 }
1526 }
1527 }
1528
1529 out:
1530 //Dbprintf("DEBUG: Done waiting for frame");
1531
1532 LED_B_OFF();
1533 LED_D_OFF();
1534 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1535 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1536 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1537 //Dbprintf("frame received: %d",frame_count);
1538 //DbpString("All done");
1539 if (bSuccessful)
1540 cmd_send(CMD_ACK, bSuccessful, 0, 0, (uint8_t*)tag.sectors, 48);
1541 else
1542 cmd_send(CMD_ACK, bSuccessful, 0, 0, 0, 0);
1543 }
1544
1545 void WriterHitag(hitag_function htf, hitag_data *htd, int page) {
1546 // int frame_count;
1547 int response;
1548 uint8_t rx[HITAG_FRAME_LEN];
1549 size_t rxlen = 0;
1550 uint8_t txbuf[HITAG_FRAME_LEN];
1551 uint8_t *tx = txbuf;
1552 size_t txlen = 0;
1553 int lastbit;
1554 bool bSkip;
1555 int reset_sof;
1556 int tag_sof;
1557 int t_wait = HITAG_T_WAIT_MAX;
1558 bool bStop;
1559 bool bQuitTraceFull = false;
1560
1561 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
1562 // Reset the return status
1563 bSuccessful = false;
1564
1565 // Clean up trace and prepare it for storing frames
1566 set_tracing(true);
1567 clear_trace();
1568
1569 //DbpString("Starting Hitag reader family");
1570
1571 // Check configuration
1572 switch (htf) {
1573 case WHT2F_CRYPTO: {
1574 DbpString("Authenticating using key:");
1575 memcpy(key, htd->crypto.key, 6); //HACK; 4 or 6?? I read both in the code.
1576 memcpy(writedata, htd->crypto.data, 4);
1577 Dbhexdump(6, key, false);
1578 blocknr = page;
1579 bQuiet = false;
1580 bCrypto = false;
1581 bAuthenticating = false;
1582 bQuitTraceFull = true;
1583 writestate = WRITE_STATE_START;
1584 }
1585 break;
1586 case WHT2F_PASSWORD: {
1587 DbpString("Authenticating using password:");
1588 memcpy(password, htd->pwd.password, 4);
1589 memcpy(writedata, htd->crypto.data, 4);
1590 Dbhexdump(4, password, false);
1591 blocknr = page;
1592 bPwd = false;
1593 bAuthenticating = false;
1594 writestate = WRITE_STATE_START;
1595 }
1596 break;
1597 default: {
1598 Dbprintf("Error, unknown function: %d", htf);
1599 return;
1600 }
1601 break;
1602 }
1603
1604 LED_D_ON();
1605 hitag2_init();
1606
1607 // Configure output and enable pin that is connected to the FPGA (for modulating)
1608 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
1609 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
1610
1611 // Set fpga in edge detect with reader field, we can modulate as reader now
1612 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
1613
1614 // Set Frequency divisor which will drive the FPGA and analog mux selection
1615 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
1616 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
1617
1618 // Disable modulation at default, which means enable the field
1619 LOW(GPIO_SSC_DOUT);
1620
1621 // Give it a bit of time for the resonant antenna to settle.
1622 SpinDelay(30);
1623
1624 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
1625 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
1626
1627 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the tag frames
1628 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
1629 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
1630
1631 // Disable timer during configuration
1632 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1633 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1634
1635 // TC0: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), no triggers
1636 AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK;
1637
1638 // TC1: Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
1639 // external trigger rising edge, load RA on falling edge of TIOA.
1640 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_FALLING | AT91C_TC_ABETRG | AT91C_TC_LDRA_FALLING;
1641
1642 // Enable and reset counters
1643 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1644 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1645
1646 // Reset the received frame, frame count and timing info
1647 // frame_count = 0;
1648 response = 0;
1649 lastbit = 1;
1650 bStop = false;
1651
1652 // Tag specific configuration settings (sof, timings, etc.)
1653 if (htf < 10) {
1654 // hitagS settings
1655 reset_sof = 1;
1656 t_wait = 200;
1657 //DbpString("Configured for hitagS reader");
1658 } else if (htf < 20) {
1659 // hitag1 settings
1660 reset_sof = 1;
1661 t_wait = 200;
1662 //DbpString("Configured for hitag1 reader");
1663 } else if (htf < 30) {
1664 // hitag2 settings
1665 reset_sof = 4;
1666 t_wait = HITAG_T_WAIT_2;
1667 //DbpString("Configured for hitag2 reader");
1668 } else {
1669 Dbprintf("Error, unknown hitag reader type: %d", htf);
1670 return;
1671 }
1672 while (!bStop && !BUTTON_PRESS()) {
1673
1674 WDT_HIT();
1675
1676 // Check if frame was captured and store it
1677 if (rxlen > 0) {
1678 // frame_count++;
1679 if (!bQuiet) {
1680 if (!LogTraceHitag(rx, rxlen, response, 0, false)) {
1681 DbpString("Trace full");
1682 if (bQuitTraceFull) {
1683 break;
1684 } else {
1685 bQuiet = true;
1686 }
1687 }
1688 }
1689 }
1690
1691 // By default reset the transmission buffer
1692 tx = txbuf;
1693 switch (htf) {
1694 case WHT2F_CRYPTO: {
1695 bStop = !hitag2_crypto(rx, rxlen, tx, &txlen, true);
1696 }
1697 break;
1698 case WHT2F_PASSWORD: {
1699 bStop = !hitag2_password(rx, rxlen, tx, &txlen, true);
1700 }
1701 break;
1702 default: {
1703 Dbprintf("Error, unknown function: %d", htf);
1704 return;
1705 }
1706 break;
1707 }
1708
1709 // Send and store the reader command
1710 // Disable timer 1 with external trigger to avoid triggers during our own modulation
1711 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1712
1713 // Wait for HITAG_T_WAIT_2 carrier periods after the last tag bit before transmitting,
1714 // Since the clock counts since the last falling edge, a 'one' means that the
1715 // falling edge occured halfway the period. with respect to this falling edge,
1716 // we need to wait (T_Wait2 + half_tag_period) when the last was a 'one'.
1717 // All timer values are in terms of T0 units
1718 while (AT91C_BASE_TC0->TC_CV < T0*(t_wait+(HITAG_T_TAG_HALF_PERIOD*lastbit)));
1719
1720 //Dbprintf("DEBUG: Sending reader frame");
1721
1722 // Transmit the reader frame
1723 hitag_reader_send_frame(tx, txlen);
1724
1725 // Enable and reset external trigger in timer for capturing future frames
1726 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1727
1728 // Add transmitted frame to total count
1729 if (txlen > 0) {
1730 // frame_count++;
1731 if (!bQuiet) {
1732 // Store the frame in the trace
1733 if (!LogTraceHitag(tx, txlen, HITAG_T_WAIT_2, 0, true)) {
1734 if (bQuitTraceFull) {
1735 break;
1736 } else {
1737 bQuiet = true;
1738 }
1739 }
1740 }
1741 }
1742
1743 // Reset values for receiving frames
1744 memset(rx, 0x00, sizeof(rx));
1745 rxlen = 0;
1746 lastbit = 1;
1747 bSkip = true;
1748 tag_sof = reset_sof;
1749 response = 0;
1750 //Dbprintf("DEBUG: Waiting to receive frame");
1751 uint32_t errorCount = 0;
1752
1753 // Receive frame, watch for at most T0*EOF periods
1754 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_WAIT_MAX) {
1755 // Check if falling edge in tag modulation is detected
1756 if (AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
1757 // Retrieve the new timing values
1758 int ra = (AT91C_BASE_TC1->TC_RA/T0);
1759
1760 // Reset timer every frame, we have to capture the last edge for timing
1761 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
1762
1763 LED_B_ON();
1764
1765 // Capture tag frame (manchester decoding using only falling edges)
1766 if (ra >= HITAG_T_EOF) {
1767 if (rxlen != 0) {
1768 //Dbprintf("DEBUG: Wierd1");
1769 }
1770 // Capture the T0 periods that have passed since last communication or field drop (reset)
1771 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
1772 response = ra - HITAG_T_TAG_HALF_PERIOD;
1773 } else if (ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
1774 // Manchester coding example |-_|_-|-_| (101)
1775
1776 // need to test to verify we don't exceed memory...
1777 // if ( ((rxlen+2) / 8) > HITAG_FRAME_LEN) {
1778 // break;
1779 // }
1780 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1781 rxlen++;
1782 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1783 rxlen++;
1784 } else if (ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
1785 // Manchester coding example |_-|...|_-|-_| (0...01)
1786
1787 // need to test to verify we don't exceed memory...
1788 // if ( ((rxlen+2) / 8) > HITAG_FRAME_LEN) {
1789 // break;
1790 // }
1791 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1792 rxlen++;
1793 // We have to skip this half period at start and add the 'one' the second time
1794 if (!bSkip) {
1795 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1796 rxlen++;
1797 }
1798 lastbit = !lastbit;
1799 bSkip = !bSkip;
1800 } else if (ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
1801 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
1802
1803 // need to test to verify we don't exceed memory...
1804 // if ( ((rxlen+2) / 8) > HITAG_FRAME_LEN) {
1805 // break;
1806 // }
1807 if (tag_sof) {
1808 // Ignore bits that are transmitted during SOF
1809 tag_sof--;
1810 } else {
1811 // bit is same as last bit
1812 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
1813 rxlen++;
1814 }
1815 } else {
1816 // Dbprintf("DEBUG: Wierd2");
1817 errorCount++;
1818 // Ignore wierd value, it is too small to mean anything
1819 }
1820 }
1821 // if we saw over 100 wierd values break it probably isn't hitag...
1822 if (errorCount > 100) break;
1823 // We can break this loop if we received the last bit from a frame
1824 if (AT91C_BASE_TC1->TC_CV > T0*HITAG_T_EOF) {
1825 if (rxlen > 0) break;
1826 }
1827 }
1828
1829 // Wait some extra time for flash to be programmed
1830 if ((rxlen == 0) && (writestate == WRITE_STATE_PROG)) {
1831 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
1832 while (AT91C_BASE_TC0->TC_CV < T0*(HITAG_T_PROG - HITAG_T_WAIT_MAX));
1833 }
1834 }
1835 //Dbprintf("DEBUG: Done waiting for frame");
1836
1837 LED_B_OFF();
1838 LED_D_OFF();
1839 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1840 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1841 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1842 //Dbprintf("frame received: %d",frame_count);
1843 //DbpString("All done");
1844 cmd_send(CMD_ACK, bSuccessful, 0, 0, (uint8_t*)tag.sectors, 48);
1845 }
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