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[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 "proxmark3.h"
20 #include "apps.h"
21 #include "util.h"
22 #include "hitag2.h"
23 #include "string.h"
24 #include "BigBuf.h"
25
26 static bool bQuiet;
27
28 static bool bCrypto;
29 static bool bAuthenticating;
30 static bool bPwd;
31 static bool bSuccessful;
32
33
34
35 struct hitag2_tag {
36 uint32_t uid;
37 enum {
38 TAG_STATE_RESET = 0x01, // Just powered up, awaiting GetSnr
39 TAG_STATE_ACTIVATING = 0x02 , // In activation phase (password mode), sent UID, awaiting reader password
40 TAG_STATE_ACTIVATED = 0x03, // Activation complete, awaiting read/write commands
41 TAG_STATE_WRITING = 0x04, // In write command, awaiting sector contents to be written
42 } state;
43 unsigned int active_sector;
44 byte_t crypto_active;
45 uint64_t cs;
46 byte_t sectors[12][4];
47 };
48
49 static struct hitag2_tag tag = {
50 .state = TAG_STATE_RESET,
51 .sectors = { // Password mode: | Crypto mode:
52 [0] = { 0x02, 0x4e, 0x02, 0x20}, // UID | UID
53 [1] = { 0x4d, 0x49, 0x4b, 0x52}, // Password RWD | 32 bit LSB key
54 [2] = { 0x20, 0xf0, 0x4f, 0x4e}, // Reserved | 16 bit MSB key, 16 bit reserved
55 [3] = { 0x0e, 0xaa, 0x48, 0x54}, // Configuration, password TAG | Configuration, password TAG
56 [4] = { 0x46, 0x5f, 0x4f, 0x4b}, // Data: F_OK
57 [5] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
58 [6] = { 0xaa, 0xaa, 0xaa, 0xaa}, // Data: ....
59 [7] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
60 [8] = { 0x00, 0x00, 0x00, 0x00}, // RSK Low
61 [9] = { 0x00, 0x00, 0x00, 0x00}, // RSK High
62 [10] = { 0x00, 0x00, 0x00, 0x00}, // RCF
63 [11] = { 0x00, 0x00, 0x00, 0x00}, // SYNC
64 },
65 };
66
67 // ToDo: define a meaningful maximum size for auth_table. The bigger this is, the lower will be the available memory for traces.
68 // Historically it used to be FREE_BUFFER_SIZE, which was 2744.
69 #define AUTH_TABLE_LENGTH 2744
70 static byte_t* auth_table;
71 static size_t auth_table_pos = 0;
72 static size_t auth_table_len = AUTH_TABLE_LENGTH;
73
74 static byte_t password[4];
75 static byte_t NrAr[8];
76 static byte_t key[8];
77 static uint64_t cipher_state;
78
79 /* Following is a modified version of cryptolib.com/ciphers/hitag2/ */
80 // Software optimized 48-bit Philips/NXP Mifare Hitag2 PCF7936/46/47/52 stream cipher algorithm by I.C. Wiener 2006-2007.
81 // For educational purposes only.
82 // No warranties or guarantees of any kind.
83 // This code is released into the public domain by its author.
84
85 // Basic macros:
86
87 #define u8 uint8_t
88 #define u32 uint32_t
89 #define u64 uint64_t
90 #define rev8(x) ((((x)>>7)&1)+((((x)>>6)&1)<<1)+((((x)>>5)&1)<<2)+((((x)>>4)&1)<<3)+((((x)>>3)&1)<<4)+((((x)>>2)&1)<<5)+((((x)>>1)&1)<<6)+(((x)&1)<<7))
91 #define rev16(x) (rev8 (x)+(rev8 (x>> 8)<< 8))
92 #define rev32(x) (rev16(x)+(rev16(x>>16)<<16))
93 #define rev64(x) (rev32(x)+(rev32(x>>32)<<32))
94 #define bit(x,n) (((x)>>(n))&1)
95 #define bit32(x,n) ((((x)[(n)>>5])>>((n)))&1)
96 #define inv32(x,i,n) ((x)[(i)>>5]^=((u32)(n))<<((i)&31))
97 #define rotl64(x, n) ((((u64)(x))<<((n)&63))+(((u64)(x))>>((0-(n))&63)))
98
99 // Single bit Hitag2 functions:
100
101 #define i4(x,a,b,c,d) ((u32)((((x)>>(a))&1)+(((x)>>(b))&1)*2+(((x)>>(c))&1)*4+(((x)>>(d))&1)*8))
102
103 static const u32 ht2_f4a = 0x2C79; // 0010 1100 0111 1001
104 static const u32 ht2_f4b = 0x6671; // 0110 0110 0111 0001
105 static const u32 ht2_f5c = 0x7907287B; // 0111 1001 0000 0111 0010 1000 0111 1011
106
107 static u32 _f20 (const u64 x)
108 {
109 u32 i5;
110
111 i5 = ((ht2_f4a >> i4 (x, 1, 2, 4, 5)) & 1)* 1
112 + ((ht2_f4b >> i4 (x, 7,11,13,14)) & 1)* 2
113 + ((ht2_f4b >> i4 (x,16,20,22,25)) & 1)* 4
114 + ((ht2_f4b >> i4 (x,27,28,30,32)) & 1)* 8
115 + ((ht2_f4a >> i4 (x,33,42,43,45)) & 1)*16;
116
117 return (ht2_f5c >> i5) & 1;
118 }
119
120 static u64 _hitag2_init (const u64 key, const u32 serial, const u32 IV)
121 {
122 u32 i;
123 u64 x = ((key & 0xFFFF) << 32) + serial;
124
125 for (i = 0; i < 32; i++)
126 {
127 x >>= 1;
128 x += (u64) (_f20 (x) ^ (((IV >> i) ^ (key >> (i+16))) & 1)) << 47;
129 }
130 return x;
131 }
132
133 static u64 _hitag2_round (u64 *state)
134 {
135 u64 x = *state;
136
137 x = (x >> 1) +
138 ((((x >> 0) ^ (x >> 2) ^ (x >> 3) ^ (x >> 6)
139 ^ (x >> 7) ^ (x >> 8) ^ (x >> 16) ^ (x >> 22)
140 ^ (x >> 23) ^ (x >> 26) ^ (x >> 30) ^ (x >> 41)
141 ^ (x >> 42) ^ (x >> 43) ^ (x >> 46) ^ (x >> 47)) & 1) << 47);
142
143 *state = x;
144 return _f20 (x);
145 }
146
147 static u32 _hitag2_byte (u64 * x)
148 {
149 u32 i, c;
150
151 for (i = 0, c = 0; i < 8; i++) c += (u32) _hitag2_round (x) << (i^7);
152 return c;
153 }
154
155 static int hitag2_reset(void)
156 {
157 tag.state = TAG_STATE_RESET;
158 tag.crypto_active = 0;
159 return 0;
160 }
161
162 static int hitag2_init(void)
163 {
164 // memcpy(&tag, &resetdata, sizeof(tag));
165 hitag2_reset();
166 return 0;
167 }
168
169 static void hitag2_cipher_reset(struct hitag2_tag *tag, const byte_t *iv)
170 {
171 uint64_t key = ((uint64_t)tag->sectors[2][2]) |
172 ((uint64_t)tag->sectors[2][3] << 8) |
173 ((uint64_t)tag->sectors[1][0] << 16) |
174 ((uint64_t)tag->sectors[1][1] << 24) |
175 ((uint64_t)tag->sectors[1][2] << 32) |
176 ((uint64_t)tag->sectors[1][3] << 40);
177 uint32_t uid = ((uint32_t)tag->sectors[0][0]) |
178 ((uint32_t)tag->sectors[0][1] << 8) |
179 ((uint32_t)tag->sectors[0][2] << 16) |
180 ((uint32_t)tag->sectors[0][3] << 24);
181 uint32_t iv_ = (((uint32_t)(iv[0]))) |
182 (((uint32_t)(iv[1])) << 8) |
183 (((uint32_t)(iv[2])) << 16) |
184 (((uint32_t)(iv[3])) << 24);
185 tag->cs = _hitag2_init(rev64(key), rev32(uid), rev32(iv_));
186 }
187
188 static int hitag2_cipher_authenticate(uint64_t* cs, const byte_t *authenticator_is)
189 {
190 byte_t authenticator_should[4];
191 authenticator_should[0] = ~_hitag2_byte(cs);
192 authenticator_should[1] = ~_hitag2_byte(cs);
193 authenticator_should[2] = ~_hitag2_byte(cs);
194 authenticator_should[3] = ~_hitag2_byte(cs);
195 return (memcmp(authenticator_should, authenticator_is, 4) == 0);
196 }
197
198 static int hitag2_cipher_transcrypt(uint64_t* cs, byte_t *data, unsigned int bytes, unsigned int bits)
199 {
200 int i;
201 for(i=0; i<bytes; i++) data[i] ^= _hitag2_byte(cs);
202 for(i=0; i<bits; i++) data[bytes] ^= _hitag2_round(cs) << (7-i);
203 return 0;
204 }
205
206 // Sam7s has several timers, we will use the source TIMER_CLOCK1 (aka AT91C_TC_CLKS_TIMER_DIV1_CLOCK)
207 // TIMER_CLOCK1 = MCK/2, MCK is running at 48 MHz, Timer is running at 48/2 = 24 MHz
208 // Hitag units (T0) have duration of 8 microseconds (us), which is 1/125000 per second (carrier)
209 // T0 = TIMER_CLOCK1 / 125000 = 192
210 #define T0 192
211
212 #define SHORT_COIL() LOW(GPIO_SSC_DOUT)
213 #define OPEN_COIL() HIGH(GPIO_SSC_DOUT)
214
215 #define HITAG_FRAME_LEN 20
216 #define HITAG_T_STOP 36 /* T_EOF should be > 36 */
217 #define HITAG_T_LOW 8 /* T_LOW should be 4..10 */
218 #define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */
219 #define HITAG_T_1_MIN 25 /* T[1] should be 26..30 */
220 //#define HITAG_T_EOF 40 /* T_EOF should be > 36 */
221 #define HITAG_T_EOF 80 /* T_EOF should be > 36 */
222 #define HITAG_T_WAIT_1 200 /* T_wresp should be 199..206 */
223 #define HITAG_T_WAIT_2 90 /* T_wresp should be 199..206 */
224 #define HITAG_T_WAIT_MAX 300 /* bit more than HITAG_T_WAIT_1 + HITAG_T_WAIT_2 */
225
226 #define HITAG_T_TAG_ONE_HALF_PERIOD 10
227 #define HITAG_T_TAG_TWO_HALF_PERIOD 25
228 #define HITAG_T_TAG_THREE_HALF_PERIOD 41
229 #define HITAG_T_TAG_FOUR_HALF_PERIOD 57
230
231 #define HITAG_T_TAG_HALF_PERIOD 16
232 #define HITAG_T_TAG_FULL_PERIOD 32
233
234 #define HITAG_T_TAG_CAPTURE_ONE_HALF 13
235 #define HITAG_T_TAG_CAPTURE_TWO_HALF 25
236 #define HITAG_T_TAG_CAPTURE_THREE_HALF 41
237 #define HITAG_T_TAG_CAPTURE_FOUR_HALF 57
238
239
240 static void hitag_send_bit(int bit) {
241 LED_A_ON();
242 // Reset clock for the next bit
243 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
244
245 // Fixed modulation, earlier proxmark version used inverted signal
246 if(bit == 0) {
247 // Manchester: Unloaded, then loaded |__--|
248 LOW(GPIO_SSC_DOUT);
249 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
250 HIGH(GPIO_SSC_DOUT);
251 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
252 } else {
253 // Manchester: Loaded, then unloaded |--__|
254 HIGH(GPIO_SSC_DOUT);
255 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
256 LOW(GPIO_SSC_DOUT);
257 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
258 }
259 LED_A_OFF();
260 }
261
262 static void hitag_send_frame(const byte_t* frame, size_t frame_len)
263 {
264 // Send start of frame
265 for(size_t i=0; i<5; i++) {
266 hitag_send_bit(1);
267 }
268
269 // Send the content of the frame
270 for(size_t i=0; i<frame_len; i++) {
271 hitag_send_bit((frame[i/8] >> (7-(i%8)))&1);
272 }
273
274 // Drop the modulation
275 LOW(GPIO_SSC_DOUT);
276 }
277
278
279 static void hitag2_handle_reader_command(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen)
280 {
281 byte_t rx_air[HITAG_FRAME_LEN];
282
283 // Copy the (original) received frame how it is send over the air
284 memcpy(rx_air,rx,nbytes(rxlen));
285
286 if(tag.crypto_active) {
287 hitag2_cipher_transcrypt(&(tag.cs),rx,rxlen/8,rxlen%8);
288 }
289
290 // Reset the transmission frame length
291 *txlen = 0;
292
293 // Try to find out which command was send by selecting on length (in bits)
294 switch (rxlen) {
295 // Received 11000 from the reader, request for UID, send UID
296 case 05: {
297 // Always send over the air in the clear plaintext mode
298 if(rx_air[0] != 0xC0) {
299 // Unknown frame ?
300 return;
301 }
302 *txlen = 32;
303 memcpy(tx,tag.sectors[0],4);
304 tag.crypto_active = 0;
305 }
306 break;
307
308 // Read/Write command: ..xx x..y yy with yyy == ~xxx, xxx is sector number
309 case 10: {
310 unsigned int sector = (~( ((rx[0]<<2)&0x04) | ((rx[1]>>6)&0x03) ) & 0x07);
311 // Verify complement of sector index
312 if(sector != ((rx[0]>>3)&0x07)) {
313 //DbpString("Transmission error (read/write)");
314 return;
315 }
316
317 switch (rx[0] & 0xC6) {
318 // Read command: 11xx x00y
319 case 0xC0:
320 memcpy(tx,tag.sectors[sector],4);
321 *txlen = 32;
322 break;
323
324 // Inverted Read command: 01xx x10y
325 case 0x44:
326 for (size_t i=0; i<4; i++) {
327 tx[i] = tag.sectors[sector][i] ^ 0xff;
328 }
329 *txlen = 32;
330 break;
331
332 // Write command: 10xx x01y
333 case 0x82:
334 // Prepare write, acknowledge by repeating command
335 memcpy(tx,rx,nbytes(rxlen));
336 *txlen = rxlen;
337 tag.active_sector = sector;
338 tag.state=TAG_STATE_WRITING;
339 break;
340
341 // Unknown command
342 default:
343 Dbprintf("Uknown command: %02x %02x",rx[0],rx[1]);
344 return;
345 break;
346 }
347 }
348 break;
349
350 // Writing data or Reader password
351 case 32: {
352 if(tag.state == TAG_STATE_WRITING) {
353 // These are the sector contents to be written. We don't have to do anything else.
354 memcpy(tag.sectors[tag.active_sector],rx,nbytes(rxlen));
355 tag.state=TAG_STATE_RESET;
356 return;
357 } else {
358 // Received RWD password, respond with configuration and our password
359 if(memcmp(rx,tag.sectors[1],4) != 0) {
360 DbpString("Reader password is wrong");
361 return;
362 }
363 *txlen = 32;
364 memcpy(tx,tag.sectors[3],4);
365 }
366 }
367 break;
368
369 // Received RWD authentication challenge and respnse
370 case 64: {
371 // Store the authentication attempt
372 if (auth_table_len < (AUTH_TABLE_LENGTH-8)) {
373 memcpy(auth_table+auth_table_len,rx,8);
374 auth_table_len += 8;
375 }
376
377 // Reset the cipher state
378 hitag2_cipher_reset(&tag,rx);
379 // Check if the authentication was correct
380 if(!hitag2_cipher_authenticate(&(tag.cs),rx+4)) {
381 // The reader failed to authenticate, do nothing
382 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]);
383 return;
384 }
385 // Succesful, but commented out reporting back to the Host, this may delay to much.
386 // 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]);
387
388 // Activate encryption algorithm for all further communication
389 tag.crypto_active = 1;
390
391 // Use the tag password as response
392 memcpy(tx,tag.sectors[3],4);
393 *txlen = 32;
394 }
395 break;
396 }
397
398 // LogTraceHitag(rx,rxlen,0,0,false);
399 // LogTraceHitag(tx,*txlen,0,0,true);
400
401 if(tag.crypto_active) {
402 hitag2_cipher_transcrypt(&(tag.cs), tx, *txlen/8, *txlen%8);
403 }
404 }
405
406 static void hitag_reader_send_bit(int bit) {
407 LED_A_ON();
408 // Reset clock for the next bit
409 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
410
411 // Binary puls length modulation (BPLM) is used to encode the data stream
412 // This means that a transmission of a one takes longer than that of a zero
413
414 // Enable modulation, which means, drop the the field
415 HIGH(GPIO_SSC_DOUT);
416
417 // Wait for 4-10 times the carrier period
418 while(AT91C_BASE_TC0->TC_CV < T0*6);
419 // SpinDelayUs(8*8);
420
421 // Disable modulation, just activates the field again
422 LOW(GPIO_SSC_DOUT);
423
424 if(bit == 0) {
425 // Zero bit: |_-|
426 while(AT91C_BASE_TC0->TC_CV < T0*22);
427 // SpinDelayUs(16*8);
428 } else {
429 // One bit: |_--|
430 while(AT91C_BASE_TC0->TC_CV < T0*28);
431 // SpinDelayUs(22*8);
432 }
433 LED_A_OFF();
434 }
435
436
437 static void hitag_reader_send_frame(const byte_t* frame, size_t frame_len)
438 {
439 // Send the content of the frame
440 for(size_t i=0; i<frame_len; i++) {
441 hitag_reader_send_bit((frame[i/8] >> (7-(i%8)))&1);
442 }
443 // Send EOF
444 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
445 // Enable modulation, which means, drop the the field
446 HIGH(GPIO_SSC_DOUT);
447 // Wait for 4-10 times the carrier period
448 while(AT91C_BASE_TC0->TC_CV < T0*6);
449 // Disable modulation, just activates the field again
450 LOW(GPIO_SSC_DOUT);
451 }
452
453 size_t blocknr;
454
455 static bool hitag2_password(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
456 // Reset the transmission frame length
457 *txlen = 0;
458
459 // Try to find out which command was send by selecting on length (in bits)
460 switch (rxlen) {
461 // No answer, try to resurrect
462 case 0: {
463 // Stop if there is no answer (after sending password)
464 if (bPwd) {
465 DbpString("Password failed!");
466 return false;
467 }
468 *txlen = 5;
469 memcpy(tx,"\xc0",nbytes(*txlen));
470 } break;
471
472 // Received UID, tag password
473 case 32: {
474 if (!bPwd) {
475 *txlen = 32;
476 memcpy(tx,password,4);
477 bPwd = true;
478 memcpy(tag.sectors[blocknr],rx,4);
479 blocknr++;
480 } else {
481
482 if(blocknr == 1){
483 //store password in block1, the TAG answers with Block3, but we need the password in memory
484 memcpy(tag.sectors[blocknr],tx,4);
485 }else{
486 memcpy(tag.sectors[blocknr],rx,4);
487 }
488
489 blocknr++;
490 if (blocknr > 7) {
491 DbpString("Read succesful!");
492 bSuccessful = true;
493 return false;
494 }
495 *txlen = 10;
496 tx[0] = 0xc0 | (blocknr << 3) | ((blocknr^7) >> 2);
497 tx[1] = ((blocknr^7) << 6);
498 }
499 } break;
500
501 // Unexpected response
502 default: {
503 Dbprintf("Uknown frame length: %d",rxlen);
504 return false;
505 } break;
506 }
507 return true;
508 }
509
510 static bool hitag2_crypto(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
511 // Reset the transmission frame length
512 *txlen = 0;
513
514 if(bCrypto) {
515 hitag2_cipher_transcrypt(&cipher_state,rx,rxlen/8,rxlen%8);
516 }
517
518 // Try to find out which command was send by selecting on length (in bits)
519 switch (rxlen) {
520 // No answer, try to resurrect
521 case 0: {
522 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
523 if (bCrypto) {
524 // Failed during authentication
525 if (bAuthenticating) {
526 DbpString("Authentication failed!");
527 return false;
528 } else {
529 // Failed reading a block, could be (read/write) locked, skip block and re-authenticate
530 if (blocknr == 1) {
531 // Write the low part of the key in memory
532 memcpy(tag.sectors[1],key+2,4);
533 } else if (blocknr == 2) {
534 // Write the high part of the key in memory
535 tag.sectors[2][0] = 0x00;
536 tag.sectors[2][1] = 0x00;
537 tag.sectors[2][2] = key[0];
538 tag.sectors[2][3] = key[1];
539 } else {
540 // Just put zero's in the memory (of the unreadable block)
541 memset(tag.sectors[blocknr],0x00,4);
542 }
543 blocknr++;
544 bCrypto = false;
545 }
546 } else {
547 *txlen = 5;
548 memcpy(tx,"\xc0",nbytes(*txlen));
549 }
550 } break;
551
552 // Received UID, crypto tag answer
553 case 32: {
554 if (!bCrypto) {
555 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;
556 uint32_t ui32uid = rx[0] | ((uint32_t)rx[1]) << 8 | ((uint32_t)rx[2]) << 16 | ((uint32_t)rx[3]) << 24;
557 cipher_state = _hitag2_init(rev64(ui64key), rev32(ui32uid), 0);
558 memset(tx,0x00,4);
559 memset(tx+4,0xff,4);
560 hitag2_cipher_transcrypt(&cipher_state,tx+4,4,0);
561 *txlen = 64;
562 bCrypto = true;
563 bAuthenticating = true;
564 } else {
565 // Check if we received answer tag (at)
566 if (bAuthenticating) {
567 bAuthenticating = false;
568 } else {
569 // Store the received block
570 memcpy(tag.sectors[blocknr],rx,4);
571 blocknr++;
572 }
573 if (blocknr > 7) {
574 DbpString("Read succesful!");
575 bSuccessful = true;
576 return false;
577 }
578 *txlen = 10;
579 tx[0] = 0xc0 | (blocknr << 3) | ((blocknr^7) >> 2);
580 tx[1] = ((blocknr^7) << 6);
581 }
582 } break;
583
584 // Unexpected response
585 default: {
586 Dbprintf("Uknown frame length: %d",rxlen);
587 return false;
588 } break;
589 }
590
591
592 if(bCrypto) {
593 // We have to return now to avoid double encryption
594 if (!bAuthenticating) {
595 hitag2_cipher_transcrypt(&cipher_state,tx,*txlen/8,*txlen%8);
596 }
597 }
598
599 return true;
600 }
601
602
603 static bool hitag2_authenticate(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
604 // Reset the transmission frame length
605 *txlen = 0;
606
607 // Try to find out which command was send by selecting on length (in bits)
608 switch (rxlen) {
609 // No answer, try to resurrect
610 case 0: {
611 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
612 if (bCrypto) {
613 DbpString("Authentication failed!");
614 return false;
615 }
616 *txlen = 5;
617 memcpy(tx,"\xc0",nbytes(*txlen));
618 } break;
619
620 // Received UID, crypto tag answer
621 case 32: {
622 if (!bCrypto) {
623 *txlen = 64;
624 memcpy(tx,NrAr,8);
625 bCrypto = true;
626 } else {
627 DbpString("Authentication succesful!");
628 // We are done... for now
629 return false;
630 }
631 } break;
632
633 // Unexpected response
634 default: {
635 Dbprintf("Uknown frame length: %d",rxlen);
636 return false;
637 } break;
638 }
639
640 return true;
641 }
642
643
644 static bool hitag2_test_auth_attempts(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
645
646 // Reset the transmission frame length
647 *txlen = 0;
648
649 // Try to find out which command was send by selecting on length (in bits)
650 switch (rxlen) {
651 // No answer, try to resurrect
652 case 0: {
653 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
654 if (bCrypto) {
655 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]);
656
657 // Removing failed entry from authentiations table
658 memcpy(auth_table+auth_table_pos,auth_table+auth_table_pos+8,8);
659 auth_table_len -= 8;
660
661 // Return if we reached the end of the authentications table
662 bCrypto = false;
663 if (auth_table_pos == auth_table_len) {
664 return false;
665 }
666
667 // Copy the next authentication attempt in row (at the same position, b/c we removed last failed entry)
668 memcpy(NrAr,auth_table+auth_table_pos,8);
669 }
670 *txlen = 5;
671 memcpy(tx,"\xc0",nbytes(*txlen));
672 } break;
673
674 // Received UID, crypto tag answer, or read block response
675 case 32: {
676 if (!bCrypto) {
677 *txlen = 64;
678 memcpy(tx,NrAr,8);
679 bCrypto = true;
680 } else {
681 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]);
682 bCrypto = false;
683 if ((auth_table_pos+8) == auth_table_len) {
684 return false;
685 }
686 auth_table_pos += 8;
687 memcpy(NrAr,auth_table+auth_table_pos,8);
688 }
689 } break;
690
691 default: {
692 Dbprintf("Uknown frame length: %d",rxlen);
693 return false;
694 } break;
695 }
696
697 return true;
698 }
699
700
701 void SnoopHitag(uint32_t type) {
702 int frame_count;
703 int response;
704 int overflow;
705 bool rising_edge;
706 bool reader_frame;
707 int lastbit;
708 bool bSkip;
709 int tag_sof;
710 byte_t rx[HITAG_FRAME_LEN];
711 size_t rxlen=0;
712
713 auth_table_len = 0;
714 auth_table_pos = 0;
715 BigBuf_free();
716 auth_table = (byte_t *)BigBuf_malloc(AUTH_TABLE_LENGTH);
717 memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
718
719 // Clean up trace and prepare it for storing frames
720 set_tracing(TRUE);
721 clear_trace();
722
723 DbpString("Starting Hitag2 snoop");
724 LED_D_ON();
725
726 // Set up eavesdropping mode, frequency divisor which will drive the FPGA
727 // and analog mux selection.
728 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
729 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_TOGGLE_MODE);
730 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
731 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
732 RELAY_OFF();
733
734 // Configure output pin that is connected to the FPGA (for modulating)
735 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
736 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
737
738 // Disable modulation, we are going to eavesdrop, not modulate ;)
739 LOW(GPIO_SSC_DOUT);
740
741 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
742 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
743 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
744
745 // Disable timer during configuration
746 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
747
748 // Capture mode, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
749 // external trigger rising edge, load RA on rising edge of TIOA.
750 uint32_t t1_channel_mode = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_BOTH | AT91C_TC_ABETRG | AT91C_TC_LDRA_BOTH;
751 AT91C_BASE_TC1->TC_CMR = t1_channel_mode;
752
753 // Enable and reset counter
754 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
755
756 // Reset the received frame, frame count and timing info
757 memset(rx,0x00,sizeof(rx));
758 frame_count = 0;
759 response = 0;
760 overflow = 0;
761 reader_frame = false;
762 lastbit = 1;
763 bSkip = true;
764 tag_sof = 4;
765
766 while(!BUTTON_PRESS()) {
767 // Watchdog hit
768 WDT_HIT();
769
770 // Receive frame, watch for at most T0*EOF periods
771 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_EOF) {
772 // Check if rising edge in modulation is detected
773 if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
774 // Retrieve the new timing values
775 int ra = (AT91C_BASE_TC1->TC_RA/T0);
776
777 // Find out if we are dealing with a rising or falling edge
778 rising_edge = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME) > 0;
779
780 // Shorter periods will only happen with reader frames
781 if (!reader_frame && rising_edge && ra < HITAG_T_TAG_CAPTURE_ONE_HALF) {
782 // Switch from tag to reader capture
783 LED_C_OFF();
784 reader_frame = true;
785 memset(rx,0x00,sizeof(rx));
786 rxlen = 0;
787 }
788
789 // Only handle if reader frame and rising edge, or tag frame and falling edge
790 if (reader_frame != rising_edge) {
791 overflow += ra;
792 continue;
793 }
794
795 // Add the buffered timing values of earlier captured edges which were skipped
796 ra += overflow;
797 overflow = 0;
798
799 if (reader_frame) {
800 LED_B_ON();
801 // Capture reader frame
802 if(ra >= HITAG_T_STOP) {
803 if (rxlen != 0) {
804 //DbpString("wierd0?");
805 }
806 // Capture the T0 periods that have passed since last communication or field drop (reset)
807 response = (ra - HITAG_T_LOW);
808 } else if(ra >= HITAG_T_1_MIN ) {
809 // '1' bit
810 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
811 rxlen++;
812 } else if(ra >= HITAG_T_0_MIN) {
813 // '0' bit
814 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
815 rxlen++;
816 } else {
817 // Ignore wierd value, is to small to mean anything
818 }
819 } else {
820 LED_C_ON();
821 // Capture tag frame (manchester decoding using only falling edges)
822 if(ra >= HITAG_T_EOF) {
823 if (rxlen != 0) {
824 //DbpString("wierd1?");
825 }
826 // Capture the T0 periods that have passed since last communication or field drop (reset)
827 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
828 response = ra-HITAG_T_TAG_HALF_PERIOD;
829 } else if(ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
830 // Manchester coding example |-_|_-|-_| (101)
831 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
832 rxlen++;
833 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
834 rxlen++;
835 } else if(ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
836 // Manchester coding example |_-|...|_-|-_| (0...01)
837 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
838 rxlen++;
839 // We have to skip this half period at start and add the 'one' the second time
840 if (!bSkip) {
841 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
842 rxlen++;
843 }
844 lastbit = !lastbit;
845 bSkip = !bSkip;
846 } else if(ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
847 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
848 if (tag_sof) {
849 // Ignore bits that are transmitted during SOF
850 tag_sof--;
851 } else {
852 // bit is same as last bit
853 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
854 rxlen++;
855 }
856 } else {
857 // Ignore wierd value, is to small to mean anything
858 }
859 }
860 }
861 }
862
863 // Check if frame was captured
864 if(rxlen > 0) {
865 frame_count++;
866 if (!LogTraceHitag(rx,rxlen,response,0,reader_frame)) {
867 DbpString("Trace full");
868 break;
869 }
870
871 // Check if we recognize a valid authentication attempt
872 if (nbytes(rxlen) == 8) {
873 // Store the authentication attempt
874 if (auth_table_len < (AUTH_TABLE_LENGTH-8)) {
875 memcpy(auth_table+auth_table_len,rx,8);
876 auth_table_len += 8;
877 }
878 }
879
880 // Reset the received frame and response timing info
881 memset(rx,0x00,sizeof(rx));
882 response = 0;
883 reader_frame = false;
884 lastbit = 1;
885 bSkip = true;
886 tag_sof = 4;
887 overflow = 0;
888
889 LED_B_OFF();
890 LED_C_OFF();
891 } else {
892 // Save the timer overflow, will be 0 when frame was received
893 overflow += (AT91C_BASE_TC1->TC_CV/T0);
894 }
895 // Reset the frame length
896 rxlen = 0;
897 // Reset the timer to restart while-loop that receives frames
898 AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
899 }
900 LED_A_ON();
901 LED_B_OFF();
902 LED_C_OFF();
903 LED_D_OFF();
904 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
905 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
906 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
907 LED_A_OFF();
908
909 // Dbprintf("frame received: %d",frame_count);
910 // Dbprintf("Authentication Attempts: %d",(auth_table_len/8));
911 // DbpString("All done");
912 }
913
914 void SimulateHitagTag(bool tag_mem_supplied, byte_t* data) {
915 int frame_count;
916 int response;
917 int overflow;
918 byte_t rx[HITAG_FRAME_LEN];
919 size_t rxlen=0;
920 byte_t tx[HITAG_FRAME_LEN];
921 size_t txlen=0;
922 bool bQuitTraceFull = false;
923 bQuiet = false;
924
925 auth_table_len = 0;
926 auth_table_pos = 0;
927 byte_t* auth_table;
928 BigBuf_free();
929 auth_table = (byte_t *)BigBuf_malloc(AUTH_TABLE_LENGTH);
930 memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
931
932 // Clean up trace and prepare it for storing frames
933 set_tracing(TRUE);
934 clear_trace();
935
936 DbpString("Starting Hitag2 simulation");
937 LED_D_ON();
938 hitag2_init();
939
940 if (tag_mem_supplied) {
941 DbpString("Loading hitag2 memory...");
942 memcpy((byte_t*)tag.sectors,data,48);
943 }
944
945 uint32_t block = 0;
946 for (size_t i=0; i<12; i++) {
947 for (size_t j=0; j<4; j++) {
948 block <<= 8;
949 block |= tag.sectors[i][j];
950 }
951 Dbprintf("| %d | %08x |",i,block);
952 }
953
954 // Set up simulator mode, frequency divisor which will drive the FPGA
955 // and analog mux selection.
956 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
957 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
958 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
959 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
960 RELAY_OFF();
961
962 // Configure output pin that is connected to the FPGA (for modulating)
963 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
964 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
965
966 // Disable modulation at default, which means release resistance
967 LOW(GPIO_SSC_DOUT);
968
969 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
970 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
971
972 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
973 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
974 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
975
976 // Disable timer during configuration
977 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
978
979 // Capture mode, default timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
980 // external trigger rising edge, load RA on rising edge of TIOA.
981 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_RISING | AT91C_TC_ABETRG | AT91C_TC_LDRA_RISING;
982
983 // Reset the received frame, frame count and timing info
984 memset(rx,0x00,sizeof(rx));
985 frame_count = 0;
986 response = 0;
987 overflow = 0;
988
989 // Enable and reset counter
990 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
991
992 while(!BUTTON_PRESS()) {
993 // Watchdog hit
994 WDT_HIT();
995
996 // Receive frame, watch for at most T0*EOF periods
997 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_EOF) {
998 // Check if rising edge in modulation is detected
999 if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
1000 // Retrieve the new timing values
1001 int ra = (AT91C_BASE_TC1->TC_RA/T0) + overflow;
1002 overflow = 0;
1003
1004 // Reset timer every frame, we have to capture the last edge for timing
1005 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1006
1007 LED_B_ON();
1008
1009 // Capture reader frame
1010 if(ra >= HITAG_T_STOP) {
1011 if (rxlen != 0) {
1012 //DbpString("wierd0?");
1013 }
1014 // Capture the T0 periods that have passed since last communication or field drop (reset)
1015 response = (ra - HITAG_T_LOW);
1016 } else if(ra >= HITAG_T_1_MIN ) {
1017 // '1' bit
1018 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1019 rxlen++;
1020 } else if(ra >= HITAG_T_0_MIN) {
1021 // '0' bit
1022 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1023 rxlen++;
1024 } else {
1025 // Ignore wierd value, is to small to mean anything
1026 }
1027 }
1028 }
1029
1030 // Check if frame was captured
1031 if(rxlen > 4) {
1032 frame_count++;
1033 if (!bQuiet) {
1034 if (!LogTraceHitag(rx,rxlen,response,0,true)) {
1035 DbpString("Trace full");
1036 if (bQuitTraceFull) {
1037 break;
1038 } else {
1039 bQuiet = true;
1040 }
1041 }
1042 }
1043
1044 // Disable timer 1 with external trigger to avoid triggers during our own modulation
1045 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1046
1047 // Process the incoming frame (rx) and prepare the outgoing frame (tx)
1048 hitag2_handle_reader_command(rx,rxlen,tx,&txlen);
1049
1050 // Wait for HITAG_T_WAIT_1 carrier periods after the last reader bit,
1051 // not that since the clock counts since the rising edge, but T_Wait1 is
1052 // with respect to the falling edge, we need to wait actually (T_Wait1 - T_Low)
1053 // periods. The gap time T_Low varies (4..10). All timer values are in
1054 // terms of T0 units
1055 while(AT91C_BASE_TC0->TC_CV < T0*(HITAG_T_WAIT_1-HITAG_T_LOW));
1056
1057 // Send and store the tag answer (if there is any)
1058 if (txlen) {
1059 // Transmit the tag frame
1060 hitag_send_frame(tx,txlen);
1061 // Store the frame in the trace
1062 if (!bQuiet) {
1063 if (!LogTraceHitag(tx,txlen,0,0,false)) {
1064 DbpString("Trace full");
1065 if (bQuitTraceFull) {
1066 break;
1067 } else {
1068 bQuiet = true;
1069 }
1070 }
1071 }
1072 }
1073
1074 // Reset the received frame and response timing info
1075 memset(rx,0x00,sizeof(rx));
1076 response = 0;
1077
1078 // Enable and reset external trigger in timer for capturing future frames
1079 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1080 LED_B_OFF();
1081 }
1082 // Reset the frame length
1083 rxlen = 0;
1084 // Save the timer overflow, will be 0 when frame was received
1085 overflow += (AT91C_BASE_TC1->TC_CV/T0);
1086 // Reset the timer to restart while-loop that receives frames
1087 AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
1088 }
1089 LED_B_OFF();
1090 LED_D_OFF();
1091 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1092 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1093 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1094
1095 DbpString("Sim Stopped");
1096
1097 }
1098
1099 void ReaderHitag(hitag_function htf, hitag_data* htd) {
1100 int frame_count;
1101 int response;
1102 byte_t rx[HITAG_FRAME_LEN];
1103 size_t rxlen=0;
1104 byte_t txbuf[HITAG_FRAME_LEN];
1105 byte_t* tx = txbuf;
1106 size_t txlen=0;
1107 int lastbit;
1108 bool bSkip;
1109 int reset_sof;
1110 int tag_sof;
1111 int t_wait = HITAG_T_WAIT_MAX;
1112 bool bStop;
1113 bool bQuitTraceFull = false;
1114
1115 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
1116 // Reset the return status
1117 bSuccessful = false;
1118
1119 // Clean up trace and prepare it for storing frames
1120 set_tracing(TRUE);
1121 clear_trace();
1122
1123 DbpString("Starting Hitag reader family");
1124
1125 // Check configuration
1126 switch(htf) {
1127 case RHT2F_PASSWORD: {
1128 Dbprintf("List identifier in password mode");
1129 memcpy(password,htd->pwd.password,4);
1130 blocknr = 0;
1131 bQuitTraceFull = false;
1132 bQuiet = false;
1133 bPwd = false;
1134 } break;
1135
1136 case RHT2F_AUTHENTICATE: {
1137 DbpString("Authenticating using nr,ar pair:");
1138 memcpy(NrAr,htd->auth.NrAr,8);
1139 Dbhexdump(8,NrAr,false);
1140 bQuiet = false;
1141 bCrypto = false;
1142 bAuthenticating = false;
1143 bQuitTraceFull = true;
1144 } break;
1145
1146 case RHT2F_CRYPTO: {
1147 DbpString("Authenticating using key:");
1148 memcpy(key,htd->crypto.key,4); //HACK; 4 or 6?? I read both in the code.
1149 Dbhexdump(6,key,false);
1150 blocknr = 0;
1151 bQuiet = false;
1152 bCrypto = false;
1153 bAuthenticating = false;
1154 bQuitTraceFull = true;
1155 } break;
1156
1157 case RHT2F_TEST_AUTH_ATTEMPTS: {
1158 Dbprintf("Testing %d authentication attempts",(auth_table_len/8));
1159 auth_table_pos = 0;
1160 memcpy(NrAr, auth_table, 8);
1161 bQuitTraceFull = false;
1162 bQuiet = false;
1163 bCrypto = false;
1164 } break;
1165
1166 default: {
1167 Dbprintf("Error, unknown function: %d",htf);
1168 return;
1169 } break;
1170 }
1171
1172 LED_D_ON();
1173 hitag2_init();
1174
1175 // Configure output and enable pin that is connected to the FPGA (for modulating)
1176 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
1177 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
1178
1179 // Set fpga in edge detect with reader field, we can modulate as reader now
1180 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
1181
1182 // Set Frequency divisor which will drive the FPGA and analog mux selection
1183 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
1184 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
1185 RELAY_OFF();
1186
1187 // Disable modulation at default, which means enable the field
1188 LOW(GPIO_SSC_DOUT);
1189
1190 // Give it a bit of time for the resonant antenna to settle.
1191 SpinDelay(30);
1192
1193 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
1194 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
1195
1196 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the tag frames
1197 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
1198 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
1199
1200 // Disable timer during configuration
1201 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1202
1203 // Capture mode, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
1204 // external trigger rising edge, load RA on falling edge of TIOA.
1205 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_FALLING | AT91C_TC_ABETRG | AT91C_TC_LDRA_FALLING;
1206
1207 // Enable and reset counters
1208 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1209 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1210
1211 // Reset the received frame, frame count and timing info
1212 frame_count = 0;
1213 response = 0;
1214 lastbit = 1;
1215 bStop = false;
1216
1217 // Tag specific configuration settings (sof, timings, etc.)
1218 if (htf < 10){
1219 // hitagS settings
1220 reset_sof = 1;
1221 t_wait = 200;
1222 DbpString("Configured for hitagS reader");
1223 } else if (htf < 20) {
1224 // hitag1 settings
1225 reset_sof = 1;
1226 t_wait = 200;
1227 DbpString("Configured for hitag1 reader");
1228 } else if (htf < 30) {
1229 // hitag2 settings
1230 reset_sof = 4;
1231 t_wait = HITAG_T_WAIT_2;
1232 DbpString("Configured for hitag2 reader");
1233 } else {
1234 Dbprintf("Error, unknown hitag reader type: %d",htf);
1235 return;
1236 }
1237
1238 while(!bStop && !BUTTON_PRESS()) {
1239 // Watchdog hit
1240 WDT_HIT();
1241
1242 // Check if frame was captured and store it
1243 if(rxlen > 0) {
1244 frame_count++;
1245 if (!bQuiet) {
1246 if (!LogTraceHitag(rx,rxlen,response,0,false)) {
1247 DbpString("Trace full");
1248 if (bQuitTraceFull) {
1249 break;
1250 } else {
1251 bQuiet = true;
1252 }
1253 }
1254 }
1255 }
1256
1257 // By default reset the transmission buffer
1258 tx = txbuf;
1259 switch(htf) {
1260 case RHT2F_PASSWORD: {
1261 bStop = !hitag2_password(rx,rxlen,tx,&txlen);
1262 } break;
1263 case RHT2F_AUTHENTICATE: {
1264 bStop = !hitag2_authenticate(rx,rxlen,tx,&txlen);
1265 } break;
1266 case RHT2F_CRYPTO: {
1267 bStop = !hitag2_crypto(rx,rxlen,tx,&txlen);
1268 } break;
1269 case RHT2F_TEST_AUTH_ATTEMPTS: {
1270 bStop = !hitag2_test_auth_attempts(rx,rxlen,tx,&txlen);
1271 } break;
1272 default: {
1273 Dbprintf("Error, unknown function: %d",htf);
1274 return;
1275 } break;
1276 }
1277
1278 // Send and store the reader command
1279 // Disable timer 1 with external trigger to avoid triggers during our own modulation
1280 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1281
1282 // Wait for HITAG_T_WAIT_2 carrier periods after the last tag bit before transmitting,
1283 // Since the clock counts since the last falling edge, a 'one' means that the
1284 // falling edge occured halfway the period. with respect to this falling edge,
1285 // we need to wait (T_Wait2 + half_tag_period) when the last was a 'one'.
1286 // All timer values are in terms of T0 units
1287 while(AT91C_BASE_TC0->TC_CV < T0*(t_wait+(HITAG_T_TAG_HALF_PERIOD*lastbit)));
1288
1289 // Transmit the reader frame
1290 hitag_reader_send_frame(tx,txlen);
1291
1292 // Enable and reset external trigger in timer for capturing future frames
1293 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1294
1295 // Add transmitted frame to total count
1296 if(txlen > 0) {
1297 frame_count++;
1298 if (!bQuiet) {
1299 // Store the frame in the trace
1300 if (!LogTraceHitag(tx,txlen,HITAG_T_WAIT_2,0,true)) {
1301 if (bQuitTraceFull) {
1302 break;
1303 } else {
1304 bQuiet = true;
1305 }
1306 }
1307 }
1308 }
1309
1310 // Reset values for receiving frames
1311 memset(rx,0x00,sizeof(rx));
1312 rxlen = 0;
1313 lastbit = 1;
1314 bSkip = true;
1315 tag_sof = reset_sof;
1316 response = 0;
1317
1318 // Receive frame, watch for at most T0*EOF periods
1319 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_WAIT_MAX) {
1320 // Check if falling edge in tag modulation is detected
1321 if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
1322 // Retrieve the new timing values
1323 int ra = (AT91C_BASE_TC1->TC_RA/T0);
1324
1325 // Reset timer every frame, we have to capture the last edge for timing
1326 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
1327
1328 LED_B_ON();
1329
1330 // Capture tag frame (manchester decoding using only falling edges)
1331 if(ra >= HITAG_T_EOF) {
1332 if (rxlen != 0) {
1333 //DbpString("wierd1?");
1334 }
1335 // Capture the T0 periods that have passed since last communication or field drop (reset)
1336 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
1337 response = ra-HITAG_T_TAG_HALF_PERIOD;
1338 } else if(ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
1339 // Manchester coding example |-_|_-|-_| (101)
1340 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1341 rxlen++;
1342 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1343 rxlen++;
1344 } else if(ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
1345 // Manchester coding example |_-|...|_-|-_| (0...01)
1346 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1347 rxlen++;
1348 // We have to skip this half period at start and add the 'one' the second time
1349 if (!bSkip) {
1350 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1351 rxlen++;
1352 }
1353 lastbit = !lastbit;
1354 bSkip = !bSkip;
1355 } else if(ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
1356 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
1357 if (tag_sof) {
1358 // Ignore bits that are transmitted during SOF
1359 tag_sof--;
1360 } else {
1361 // bit is same as last bit
1362 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
1363 rxlen++;
1364 }
1365 } else {
1366 // Ignore wierd value, is to small to mean anything
1367 }
1368 }
1369
1370 // We can break this loop if we received the last bit from a frame
1371 if (AT91C_BASE_TC1->TC_CV > T0*HITAG_T_EOF) {
1372 if (rxlen>0) break;
1373 }
1374 }
1375 }
1376 LED_B_OFF();
1377 LED_D_OFF();
1378 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1379 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1380 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1381 Dbprintf("frame received: %d",frame_count);
1382 DbpString("All done");
1383 cmd_send(CMD_ACK,bSuccessful,0,0,(byte_t*)tag.sectors,48);
1384 }
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