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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
25 static bool bQuiet;
26
27 bool bCrypto;
28 bool bAuthenticating;
29 bool bPwd;
30
31 struct hitag2_tag {
32 uint32_t uid;
33 enum {
34 TAG_STATE_RESET = 0x01, // Just powered up, awaiting GetSnr
35 TAG_STATE_ACTIVATING = 0x02 , // In activation phase (password mode), sent UID, awaiting reader password
36 TAG_STATE_ACTIVATED = 0x03, // Activation complete, awaiting read/write commands
37 TAG_STATE_WRITING = 0x04, // In write command, awaiting sector contents to be written
38 } state;
39 unsigned int active_sector;
40 byte_t crypto_active;
41 uint64_t cs;
42 byte_t sectors[12][4];
43 };
44
45 static struct hitag2_tag tag = {
46 .state = TAG_STATE_RESET,
47 .sectors = { // Password mode: | Crypto mode:
48 [0] = { 0x02, 0x4e, 0x02, 0x20}, // UID | UID
49 [1] = { 0x4d, 0x49, 0x4b, 0x52}, // Password RWD | 32 bit LSB key
50 [2] = { 0x20, 0xf0, 0x4f, 0x4e}, // Reserved | 16 bit MSB key, 16 bit reserved
51 [3] = { 0x0e, 0xaa, 0x48, 0x54}, // Configuration, password TAG | Configuration, password TAG
52 [4] = { 0x46, 0x5f, 0x4f, 0x4b}, // Data: F_OK
53 [5] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
54 [6] = { 0xaa, 0xaa, 0xaa, 0xaa}, // Data: ....
55 [7] = { 0x55, 0x55, 0x55, 0x55}, // Data: UUUU
56 [8] = { 0x00, 0x00, 0x00, 0x00}, // RSK Low
57 [9] = { 0x00, 0x00, 0x00, 0x00}, // RSK High
58 [10] = { 0x00, 0x00, 0x00, 0x00}, // RCF
59 [11] = { 0x00, 0x00, 0x00, 0x00}, // SYNC
60 },
61 };
62
63 //#define TRACE_LENGTH 3000
64 //uint8_t *trace = (uint8_t *) BigBuf;
65 //int traceLen = 0;
66 //int rsamples = 0;
67
68 #define AUTH_TABLE_OFFSET FREE_BUFFER_OFFSET
69 #define AUTH_TABLE_LENGTH FREE_BUFFER_SIZE
70 byte_t* auth_table = (byte_t *)BigBuf+AUTH_TABLE_OFFSET;
71 size_t auth_table_pos = 0;
72 size_t auth_table_len = AUTH_TABLE_LENGTH;
73
74 byte_t password[4];
75 byte_t NrAr[8];
76 byte_t key[8];
77 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 size_t nbytes(size_t nbits) {
156 return (nbits/8)+((nbits%8)>0);
157 }
158
159 int hitag2_reset(void)
160 {
161 tag.state = TAG_STATE_RESET;
162 tag.crypto_active = 0;
163 return 0;
164 }
165
166 int hitag2_init(void)
167 {
168 // memcpy(&tag, &resetdata, sizeof(tag));
169 hitag2_reset();
170 return 0;
171 }
172
173 static void hitag2_cipher_reset(struct hitag2_tag *tag, const byte_t *iv)
174 {
175 uint64_t key = ((uint64_t)tag->sectors[2][2]) |
176 ((uint64_t)tag->sectors[2][3] << 8) |
177 ((uint64_t)tag->sectors[1][0] << 16) |
178 ((uint64_t)tag->sectors[1][1] << 24) |
179 ((uint64_t)tag->sectors[1][2] << 32) |
180 ((uint64_t)tag->sectors[1][3] << 40);
181 uint32_t uid = ((uint32_t)tag->sectors[0][0]) |
182 ((uint32_t)tag->sectors[0][1] << 8) |
183 ((uint32_t)tag->sectors[0][2] << 16) |
184 ((uint32_t)tag->sectors[0][3] << 24);
185 uint32_t iv_ = (((uint32_t)(iv[0]))) |
186 (((uint32_t)(iv[1])) << 8) |
187 (((uint32_t)(iv[2])) << 16) |
188 (((uint32_t)(iv[3])) << 24);
189 tag->cs = _hitag2_init(rev64(key), rev32(uid), rev32(iv_));
190 }
191
192 static int hitag2_cipher_authenticate(uint64_t* cs, const byte_t *authenticator_is)
193 {
194 byte_t authenticator_should[4];
195 authenticator_should[0] = ~_hitag2_byte(cs);
196 authenticator_should[1] = ~_hitag2_byte(cs);
197 authenticator_should[2] = ~_hitag2_byte(cs);
198 authenticator_should[3] = ~_hitag2_byte(cs);
199 return (memcmp(authenticator_should, authenticator_is, 4) == 0);
200 }
201
202 static int hitag2_cipher_transcrypt(uint64_t* cs, byte_t *data, unsigned int bytes, unsigned int bits)
203 {
204 int i;
205 for(i=0; i<bytes; i++) data[i] ^= _hitag2_byte(cs);
206 for(i=0; i<bits; i++) data[bytes] ^= _hitag2_round(cs) << (7-i);
207 return 0;
208 }
209
210 // Sam7s has several timers, we will use the source TIMER_CLOCK1 (aka AT91C_TC_CLKS_TIMER_DIV1_CLOCK)
211 // TIMER_CLOCK1 = MCK/2, MCK is running at 48 MHz, Timer is running at 48/2 = 24 MHz
212 // Hitag units (T0) have duration of 8 microseconds (us), which is 1/125000 per second (carrier)
213 // T0 = TIMER_CLOCK1 / 125000 = 192
214 #define T0 192
215
216 #define SHORT_COIL() LOW(GPIO_SSC_DOUT)
217 #define OPEN_COIL() HIGH(GPIO_SSC_DOUT)
218
219 #define HITAG_FRAME_LEN 20
220 #define HITAG_T_STOP 36 /* T_EOF should be > 36 */
221 #define HITAG_T_LOW 8 /* T_LOW should be 4..10 */
222 #define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */
223 #define HITAG_T_1_MIN 25 /* T[1] should be 26..30 */
224 //#define HITAG_T_EOF 40 /* T_EOF should be > 36 */
225 #define HITAG_T_EOF 80 /* T_EOF should be > 36 */
226 #define HITAG_T_WAIT_1 200 /* T_wresp should be 199..206 */
227 #define HITAG_T_WAIT_2 90 /* T_wresp should be 199..206 */
228 #define HITAG_T_WAIT_MAX 300 /* bit more than HITAG_T_WAIT_1 + HITAG_T_WAIT_2 */
229
230 #define HITAG_T_TAG_ONE_HALF_PERIOD 10
231 #define HITAG_T_TAG_TWO_HALF_PERIOD 25
232 #define HITAG_T_TAG_THREE_HALF_PERIOD 41
233 #define HITAG_T_TAG_FOUR_HALF_PERIOD 57
234
235 #define HITAG_T_TAG_HALF_PERIOD 16
236 #define HITAG_T_TAG_FULL_PERIOD 32
237
238 #define HITAG_T_TAG_CAPTURE_ONE_HALF 13
239 #define HITAG_T_TAG_CAPTURE_TWO_HALF 25
240 #define HITAG_T_TAG_CAPTURE_THREE_HALF 41
241 #define HITAG_T_TAG_CAPTURE_FOUR_HALF 57
242
243
244 static void hitag_send_bit(int bit) {
245 LED_A_ON();
246 // Reset clock for the next bit
247 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
248
249 // Fixed modulation, earlier proxmark version used inverted signal
250 if(bit == 0) {
251 // Manchester: Unloaded, then loaded |__--|
252 LOW(GPIO_SSC_DOUT);
253 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
254 HIGH(GPIO_SSC_DOUT);
255 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
256 } else {
257 // Manchester: Loaded, then unloaded |--__|
258 HIGH(GPIO_SSC_DOUT);
259 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_HALF_PERIOD);
260 LOW(GPIO_SSC_DOUT);
261 while(AT91C_BASE_TC0->TC_CV < T0*HITAG_T_TAG_FULL_PERIOD);
262 }
263 LED_A_OFF();
264 }
265
266 static void hitag_send_frame(const byte_t* frame, size_t frame_len)
267 {
268 // Send start of frame
269 for(size_t i=0; i<5; i++) {
270 hitag_send_bit(1);
271 }
272
273 // Send the content of the frame
274 for(size_t i=0; i<frame_len; i++) {
275 hitag_send_bit((frame[i/8] >> (7-(i%8)))&1);
276 }
277
278 // Drop the modulation
279 LOW(GPIO_SSC_DOUT);
280 }
281
282 void hitag2_handle_reader_command(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen)
283 {
284 byte_t rx_air[HITAG_FRAME_LEN];
285
286 // Copy the (original) received frame how it is send over the air
287 memcpy(rx_air,rx,nbytes(rxlen));
288
289 if(tag.crypto_active) {
290 hitag2_cipher_transcrypt(&(tag.cs),rx,rxlen/8,rxlen%8);
291 }
292
293 // Reset the transmission frame length
294 *txlen = 0;
295
296 // Try to find out which command was send by selecting on length (in bits)
297 switch (rxlen) {
298 // Received 11000 from the reader, request for UID, send UID
299 case 05: {
300 // Always send over the air in the clear plaintext mode
301 if(rx_air[0] != 0xC0) {
302 // Unknown frame ?
303 return;
304 }
305 *txlen = 32;
306 memcpy(tx,tag.sectors[0],4);
307 tag.crypto_active = 0;
308 }
309 break;
310
311 // Read/Write command: ..xx x..y yy with yyy == ~xxx, xxx is sector number
312 case 10: {
313 unsigned int sector = (~( ((rx[0]<<2)&0x04) | ((rx[1]>>6)&0x03) ) & 0x07);
314 // Verify complement of sector index
315 if(sector != ((rx[0]>>3)&0x07)) {
316 //DbpString("Transmission error (read/write)");
317 return;
318 }
319
320 switch (rx[0] & 0xC6) {
321 // Read command: 11xx x00y
322 case 0xC0:
323 memcpy(tx,tag.sectors[sector],4);
324 *txlen = 32;
325 break;
326
327 // Inverted Read command: 01xx x10y
328 case 0x44:
329 for (size_t i=0; i<4; i++) {
330 tx[i] = tag.sectors[sector][i] ^ 0xff;
331 }
332 *txlen = 32;
333 break;
334
335 // Write command: 10xx x01y
336 case 0x82:
337 // Prepare write, acknowledge by repeating command
338 memcpy(tx,rx,nbytes(rxlen));
339 *txlen = rxlen;
340 tag.active_sector = sector;
341 tag.state=TAG_STATE_WRITING;
342 break;
343
344 // Unknown command
345 default:
346 Dbprintf("Uknown command: %02x %02x",rx[0],rx[1]);
347 return;
348 break;
349 }
350 }
351 break;
352
353 // Writing data or Reader password
354 case 32: {
355 if(tag.state == TAG_STATE_WRITING) {
356 // These are the sector contents to be written. We don't have to do anything else.
357 memcpy(tag.sectors[tag.active_sector],rx,nbytes(rxlen));
358 tag.state=TAG_STATE_RESET;
359 return;
360 } else {
361 // Received RWD password, respond with configuration and our password
362 if(memcmp(rx,tag.sectors[1],4) != 0) {
363 DbpString("Reader password is wrong");
364 return;
365 }
366 *txlen = 32;
367 memcpy(tx,tag.sectors[3],4);
368 }
369 }
370 break;
371
372 // Received RWD authentication challenge and respnse
373 case 64: {
374 // Store the authentication attempt
375 if (auth_table_len < (AUTH_TABLE_LENGTH-8)) {
376 memcpy(auth_table+auth_table_len,rx,8);
377 auth_table_len += 8;
378 }
379
380 // Reset the cipher state
381 hitag2_cipher_reset(&tag,rx);
382 // Check if the authentication was correct
383 if(!hitag2_cipher_authenticate(&(tag.cs),rx+4)) {
384 // The reader failed to authenticate, do nothing
385 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]);
386 return;
387 }
388 // Succesful, but commented out reporting back to the Host, this may delay to much.
389 // 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]);
390
391 // Activate encryption algorithm for all further communication
392 tag.crypto_active = 1;
393
394 // Use the tag password as response
395 memcpy(tx,tag.sectors[3],4);
396 *txlen = 32;
397 }
398 break;
399 }
400
401 // LogTrace(rx,nbytes(rxlen),0,0,false);
402 // LogTrace(tx,nbytes(*txlen),0,0,true);
403
404 if(tag.crypto_active) {
405 hitag2_cipher_transcrypt(&(tag.cs), tx, *txlen/8, *txlen%8);
406 }
407 }
408
409 static void hitag_reader_send_bit(int bit) {
410 LED_A_ON();
411 // Reset clock for the next bit
412 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
413
414 // Binary puls length modulation (BPLM) is used to encode the data stream
415 // This means that a transmission of a one takes longer than that of a zero
416
417 // Enable modulation, which means, drop the the field
418 HIGH(GPIO_SSC_DOUT);
419
420 // Wait for 4-10 times the carrier period
421 while(AT91C_BASE_TC0->TC_CV < T0*6);
422 // SpinDelayUs(8*8);
423
424 // Disable modulation, just activates the field again
425 LOW(GPIO_SSC_DOUT);
426
427 if(bit == 0) {
428 // Zero bit: |_-|
429 while(AT91C_BASE_TC0->TC_CV < T0*22);
430 // SpinDelayUs(16*8);
431 } else {
432 // One bit: |_--|
433 while(AT91C_BASE_TC0->TC_CV < T0*28);
434 // SpinDelayUs(22*8);
435 }
436 LED_A_OFF();
437 }
438
439 static void hitag_reader_send_frame(const byte_t* frame, size_t frame_len)
440 {
441 // Send the content of the frame
442 for(size_t i=0; i<frame_len; i++) {
443 hitag_reader_send_bit((frame[i/8] >> (7-(i%8)))&1);
444 }
445 // Send EOF
446 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
447 // Enable modulation, which means, drop the the field
448 HIGH(GPIO_SSC_DOUT);
449 // Wait for 4-10 times the carrier period
450 while(AT91C_BASE_TC0->TC_CV < T0*6);
451 // Disable modulation, just activates the field again
452 LOW(GPIO_SSC_DOUT);
453 }
454
455 size_t blocknr;
456
457 bool hitag2_password(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
458 // Reset the transmission frame length
459 *txlen = 0;
460
461 // Try to find out which command was send by selecting on length (in bits)
462 switch (rxlen) {
463 // No answer, try to resurrect
464 case 0: {
465 // Stop if there is no answer (after sending password)
466 if (bPwd) {
467 DbpString("Password failed!");
468 return false;
469 }
470 *txlen = 5;
471 memcpy(tx,"\xc0",nbytes(*txlen));
472 } break;
473
474 // Received UID, tag password
475 case 32: {
476 if (!bPwd) {
477 *txlen = 32;
478 memcpy(tx,password,4);
479 bPwd = true;
480 } else {
481 if (blocknr > 7) {
482 DbpString("Read succesful!");
483 // We are done... for now
484 return false;
485 }
486 *txlen = 10;
487 tx[0] = 0xc0 | (blocknr << 3) | ((blocknr^7) >> 2);
488 tx[1] = ((blocknr^7) << 6);
489 blocknr++;
490 }
491 } break;
492
493 // Unexpected response
494 default: {
495 Dbprintf("Uknown frame length: %d",rxlen);
496 return false;
497 } break;
498 }
499 return true;
500 }
501
502 bool hitag2_crypto(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
503 // Reset the transmission frame length
504 *txlen = 0;
505
506 if(bCrypto) {
507 hitag2_cipher_transcrypt(&cipher_state,rx,rxlen/8,rxlen%8);
508 }
509
510 // Try to find out which command was send by selecting on length (in bits)
511 switch (rxlen) {
512 // No answer, try to resurrect
513 case 0: {
514 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
515 if (bCrypto) {
516 DbpString("Authentication failed!");
517 return false;
518 }
519 *txlen = 5;
520 memcpy(tx,"\xc0",nbytes(*txlen));
521 } break;
522
523 // Received UID, crypto tag answer
524 case 32: {
525 if (!bCrypto) {
526 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;
527 uint32_t ui32uid = rx[0] | ((uint32_t)rx[1]) << 8 | ((uint32_t)rx[2]) << 16 | ((uint32_t)rx[3]) << 24;
528 cipher_state = _hitag2_init(rev64(ui64key), rev32(ui32uid), 0);
529 memset(tx,0x00,4);
530 memset(tx+4,0xff,4);
531 hitag2_cipher_transcrypt(&cipher_state,tx+4,4,0);
532 *txlen = 64;
533 bCrypto = true;
534 bAuthenticating = true;
535 } else {
536 // Check if we received answer tag (at)
537 if (bAuthenticating) {
538 bAuthenticating = false;
539 } else {
540 // Store the received block
541 memcpy(tag.sectors[blocknr],rx,4);
542 blocknr++;
543 }
544 if (blocknr > 7) {
545 DbpString("Read succesful!");
546 // We are done... for now
547 return false;
548 }
549 *txlen = 10;
550 tx[0] = 0xc0 | (blocknr << 3) | ((blocknr^7) >> 2);
551 tx[1] = ((blocknr^7) << 6);
552 }
553 } break;
554
555 // Unexpected response
556 default: {
557 Dbprintf("Uknown frame length: %d",rxlen);
558 return false;
559 } break;
560 }
561
562
563 if(bCrypto) {
564 // We have to return now to avoid double encryption
565 if (!bAuthenticating) {
566 hitag2_cipher_transcrypt(&cipher_state,tx,*txlen/8,*txlen%8);
567 }
568 }
569
570 return true;
571 }
572
573
574 bool hitag2_authenticate(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
575 // Reset the transmission frame length
576 *txlen = 0;
577
578 // Try to find out which command was send by selecting on length (in bits)
579 switch (rxlen) {
580 // No answer, try to resurrect
581 case 0: {
582 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
583 if (bCrypto) {
584 DbpString("Authentication failed!");
585 return false;
586 }
587 *txlen = 5;
588 memcpy(tx,"\xc0",nbytes(*txlen));
589 } break;
590
591 // Received UID, crypto tag answer
592 case 32: {
593 if (!bCrypto) {
594 *txlen = 64;
595 memcpy(tx,NrAr,8);
596 bCrypto = true;
597 } else {
598 DbpString("Authentication succesful!");
599 // We are done... for now
600 return false;
601 }
602 } break;
603
604 // Unexpected response
605 default: {
606 Dbprintf("Uknown frame length: %d",rxlen);
607 return false;
608 } break;
609 }
610
611 return true;
612 }
613
614 bool hitag2_test_auth_attempts(byte_t* rx, const size_t rxlen, byte_t* tx, size_t* txlen) {
615 // Reset the transmission frame length
616 *txlen = 0;
617
618 // Try to find out which command was send by selecting on length (in bits)
619 switch (rxlen) {
620 // No answer, try to resurrect
621 case 0: {
622 // Stop if there is no answer while we are in crypto mode (after sending NrAr)
623 if (bCrypto) {
624 Dbprintf("auth: %02x%02x%02x%02x%02x%02x%02x%02x Failed!",NrAr[0],NrAr[1],NrAr[2],NrAr[3],NrAr[4],NrAr[5],NrAr[6],NrAr[7]);
625 bCrypto = false;
626 if ((auth_table_pos+8) == auth_table_len) {
627 return false;
628 }
629 auth_table_pos += 8;
630 memcpy(NrAr,auth_table+auth_table_pos,8);
631 }
632 *txlen = 5;
633 memcpy(tx,"\xc0",nbytes(*txlen));
634 } break;
635
636 // Received UID, crypto tag answer, or read block response
637 case 32: {
638 if (!bCrypto) {
639 *txlen = 64;
640 memcpy(tx,NrAr,8);
641 bCrypto = true;
642 } else {
643 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]);
644 bCrypto = false;
645 if ((auth_table_pos+8) == auth_table_len) {
646 return false;
647 }
648 auth_table_pos += 8;
649 memcpy(NrAr,auth_table+auth_table_pos,8);
650 }
651 } break;
652
653 default: {
654 Dbprintf("Uknown frame length: %d",rxlen);
655 return false;
656 } break;
657 }
658
659 return true;
660 }
661
662 void SnoopHitag(uint32_t type) {
663 int frame_count;
664 int response;
665 int overflow;
666 bool rising_edge;
667 bool reader_frame;
668 int lastbit;
669 bool bSkip;
670 int tag_sof;
671 byte_t rx[HITAG_FRAME_LEN];
672 size_t rxlen=0;
673
674 // Clean up trace and prepare it for storing frames
675 iso14a_set_tracing(TRUE);
676 iso14a_clear_trace();
677
678 auth_table_len = 0;
679 auth_table_pos = 0;
680 memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
681
682 DbpString("Starting Hitag2 snoop");
683 LED_D_ON();
684
685 // Set up eavesdropping mode, frequency divisor which will drive the FPGA
686 // and analog mux selection.
687 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
688 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
689 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
690 RELAY_OFF();
691
692 // Configure output pin that is connected to the FPGA (for modulating)
693 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
694 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
695
696 // Disable modulation, we are going to eavesdrop, not modulate ;)
697 LOW(GPIO_SSC_DOUT);
698
699 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
700 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
701 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
702
703 // Disable timer during configuration
704 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
705
706 // Capture mode, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
707 // external trigger rising edge, load RA on rising edge of TIOA.
708 uint32_t t1_channel_mode = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_BOTH | AT91C_TC_ABETRG | AT91C_TC_LDRA_BOTH;
709 AT91C_BASE_TC1->TC_CMR = t1_channel_mode;
710
711 // Enable and reset counter
712 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
713
714 // Reset the received frame, frame count and timing info
715 memset(rx,0x00,sizeof(rx));
716 frame_count = 0;
717 response = 0;
718 overflow = 0;
719 reader_frame = false;
720 lastbit = 1;
721 bSkip = true;
722 tag_sof = 4;
723
724 while(!BUTTON_PRESS()) {
725 // Watchdog hit
726 WDT_HIT();
727
728 // Receive frame, watch for at most T0*EOF periods
729 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_EOF) {
730 // Check if rising edge in modulation is detected
731 if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
732 // Retrieve the new timing values
733 int ra = (AT91C_BASE_TC1->TC_RA/T0);
734
735 // Find out if we are dealing with a rising or falling edge
736 rising_edge = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME) > 0;
737
738 // Shorter periods will only happen with reader frames
739 if (!reader_frame && rising_edge && ra < HITAG_T_TAG_CAPTURE_ONE_HALF) {
740 // Switch from tag to reader capture
741 LED_C_OFF();
742 reader_frame = true;
743 memset(rx,0x00,sizeof(rx));
744 rxlen = 0;
745 }
746
747 // Only handle if reader frame and rising edge, or tag frame and falling edge
748 if (reader_frame != rising_edge) {
749 overflow += ra;
750 continue;
751 }
752
753 // Add the buffered timing values of earlier captured edges which were skipped
754 ra += overflow;
755 overflow = 0;
756
757 if (reader_frame) {
758 LED_B_ON();
759 // Capture reader frame
760 if(ra >= HITAG_T_STOP) {
761 if (rxlen != 0) {
762 //DbpString("wierd0?");
763 }
764 // Capture the T0 periods that have passed since last communication or field drop (reset)
765 response = (ra - HITAG_T_LOW);
766 } else if(ra >= HITAG_T_1_MIN ) {
767 // '1' bit
768 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
769 rxlen++;
770 } else if(ra >= HITAG_T_0_MIN) {
771 // '0' bit
772 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
773 rxlen++;
774 } else {
775 // Ignore wierd value, is to small to mean anything
776 }
777 } else {
778 LED_C_ON();
779 // Capture tag frame (manchester decoding using only falling edges)
780 if(ra >= HITAG_T_EOF) {
781 if (rxlen != 0) {
782 //DbpString("wierd1?");
783 }
784 // Capture the T0 periods that have passed since last communication or field drop (reset)
785 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
786 response = ra-HITAG_T_TAG_HALF_PERIOD;
787 } else if(ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
788 // Manchester coding example |-_|_-|-_| (101)
789 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
790 rxlen++;
791 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
792 rxlen++;
793 } else if(ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
794 // Manchester coding example |_-|...|_-|-_| (0...01)
795 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
796 rxlen++;
797 // We have to skip this half period at start and add the 'one' the second time
798 if (!bSkip) {
799 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
800 rxlen++;
801 }
802 lastbit = !lastbit;
803 bSkip = !bSkip;
804 } else if(ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
805 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
806 if (tag_sof) {
807 // Ignore bits that are transmitted during SOF
808 tag_sof--;
809 } else {
810 // bit is same as last bit
811 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
812 rxlen++;
813 }
814 } else {
815 // Ignore wierd value, is to small to mean anything
816 }
817 }
818 }
819 }
820
821 // Check if frame was captured
822 if(rxlen > 0) {
823 frame_count++;
824 if (!LogTrace(rx,nbytes(rxlen),response,0,reader_frame)) {
825 DbpString("Trace full");
826 break;
827 }
828
829 // Check if we recognize a valid authentication attempt
830 if (nbytes(rxlen) == 8) {
831 // Store the authentication attempt
832 if (auth_table_len < (AUTH_TABLE_LENGTH-8)) {
833 memcpy(auth_table+auth_table_len,rx,8);
834 auth_table_len += 8;
835 }
836 }
837
838 // Reset the received frame and response timing info
839 memset(rx,0x00,sizeof(rx));
840 response = 0;
841 reader_frame = false;
842 lastbit = 1;
843 bSkip = true;
844 tag_sof = 4;
845 overflow = 0;
846
847 LED_B_OFF();
848 LED_C_OFF();
849 } else {
850 // Save the timer overflow, will be 0 when frame was received
851 overflow += (AT91C_BASE_TC1->TC_CV/T0);
852 }
853 // Reset the frame length
854 rxlen = 0;
855 // Reset the timer to restart while-loop that receives frames
856 AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
857 }
858 LED_A_ON();
859 LED_B_OFF();
860 LED_C_OFF();
861 LED_D_OFF();
862 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
863 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
864 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
865 LED_A_OFF();
866
867 // Dbprintf("frame received: %d",frame_count);
868 // Dbprintf("Authentication Attempts: %d",(auth_table_len/8));
869 // DbpString("All done");
870 }
871
872 void SimulateHitagTag(bool tag_mem_supplied, byte_t* data) {
873 int frame_count;
874 int response;
875 int overflow;
876 byte_t rx[HITAG_FRAME_LEN];
877 size_t rxlen=0;
878 byte_t tx[HITAG_FRAME_LEN];
879 size_t txlen=0;
880 bool bQuitTraceFull = false;
881 bQuiet = false;
882
883 // Clean up trace and prepare it for storing frames
884 iso14a_set_tracing(TRUE);
885 iso14a_clear_trace();
886 auth_table_len = 0;
887 auth_table_pos = 0;
888 memset(auth_table, 0x00, AUTH_TABLE_LENGTH);
889
890 DbpString("Starting Hitag2 simulation");
891 LED_D_ON();
892 hitag2_init();
893
894 if (tag_mem_supplied) {
895 DbpString("Loading hitag2 memory...");
896 memcpy((byte_t*)tag.sectors,data,48);
897 }
898
899 uint32_t block = 0;
900 for (size_t i=0; i<12; i++) {
901 for (size_t j=0; j<4; j++) {
902 block <<= 8;
903 block |= tag.sectors[i][j];
904 }
905 Dbprintf("| %d | %08x |",i,block);
906 }
907
908 // Set up simulator mode, frequency divisor which will drive the FPGA
909 // and analog mux selection.
910 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
911 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
912 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
913 RELAY_OFF();
914
915 // Configure output pin that is connected to the FPGA (for modulating)
916 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
917 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
918
919 // Disable modulation at default, which means release resistance
920 LOW(GPIO_SSC_DOUT);
921
922 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
923 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
924
925 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the reader frames
926 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
927 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
928
929 // Disable timer during configuration
930 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
931
932 // Capture mode, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
933 // external trigger rising edge, load RA on rising edge of TIOA.
934 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_RISING | AT91C_TC_ABETRG | AT91C_TC_LDRA_RISING;
935
936 // Enable and reset counter
937 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
938
939 // Reset the received frame, frame count and timing info
940 memset(rx,0x00,sizeof(rx));
941 frame_count = 0;
942 response = 0;
943 overflow = 0;
944
945 while(!BUTTON_PRESS()) {
946 // Watchdog hit
947 WDT_HIT();
948
949 // Receive frame, watch for at most T0*EOF periods
950 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_EOF) {
951 // Check if rising edge in modulation is detected
952 if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
953 // Retrieve the new timing values
954 int ra = (AT91C_BASE_TC1->TC_RA/T0) + overflow;
955 overflow = 0;
956
957 // Reset timer every frame, we have to capture the last edge for timing
958 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
959
960 LED_B_ON();
961
962 // Capture reader frame
963 if(ra >= HITAG_T_STOP) {
964 if (rxlen != 0) {
965 //DbpString("wierd0?");
966 }
967 // Capture the T0 periods that have passed since last communication or field drop (reset)
968 response = (ra - HITAG_T_LOW);
969 } else if(ra >= HITAG_T_1_MIN ) {
970 // '1' bit
971 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
972 rxlen++;
973 } else if(ra >= HITAG_T_0_MIN) {
974 // '0' bit
975 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
976 rxlen++;
977 } else {
978 // Ignore wierd value, is to small to mean anything
979 }
980 }
981 }
982
983 // Check if frame was captured
984 if(rxlen > 4) {
985 frame_count++;
986 if (!bQuiet) {
987 if (!LogTrace(rx,nbytes(rxlen),response,0,true)) {
988 DbpString("Trace full");
989 if (bQuitTraceFull) {
990 break;
991 } else {
992 bQuiet = true;
993 }
994 }
995 }
996
997 // Disable timer 1 with external trigger to avoid triggers during our own modulation
998 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
999
1000 // Process the incoming frame (rx) and prepare the outgoing frame (tx)
1001 hitag2_handle_reader_command(rx,rxlen,tx,&txlen);
1002
1003 // Wait for HITAG_T_WAIT_1 carrier periods after the last reader bit,
1004 // not that since the clock counts since the rising edge, but T_Wait1 is
1005 // with respect to the falling edge, we need to wait actually (T_Wait1 - T_Low)
1006 // periods. The gap time T_Low varies (4..10). All timer values are in
1007 // terms of T0 units
1008 while(AT91C_BASE_TC0->TC_CV < T0*(HITAG_T_WAIT_1-HITAG_T_LOW));
1009
1010 // Send and store the tag answer (if there is any)
1011 if (txlen) {
1012 // Transmit the tag frame
1013 hitag_send_frame(tx,txlen);
1014 // Store the frame in the trace
1015 if (!bQuiet) {
1016 if (!LogTrace(tx,nbytes(txlen),0,0,false)) {
1017 DbpString("Trace full");
1018 if (bQuitTraceFull) {
1019 break;
1020 } else {
1021 bQuiet = true;
1022 }
1023 }
1024 }
1025 }
1026
1027 // Reset the received frame and response timing info
1028 memset(rx,0x00,sizeof(rx));
1029 response = 0;
1030
1031 // Enable and reset external trigger in timer for capturing future frames
1032 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1033 LED_B_OFF();
1034 }
1035 // Reset the frame length
1036 rxlen = 0;
1037 // Save the timer overflow, will be 0 when frame was received
1038 overflow += (AT91C_BASE_TC1->TC_CV/T0);
1039 // Reset the timer to restart while-loop that receives frames
1040 AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
1041 }
1042 LED_B_OFF();
1043 LED_D_OFF();
1044 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1045 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1046 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1047 // Dbprintf("frame received: %d",frame_count);
1048 // Dbprintf("Authentication Attempts: %d",(auth_table_len/8));
1049 // DbpString("All done");
1050 }
1051
1052 void ReaderHitag(hitag_function htf, hitag_data* htd) {
1053 int frame_count;
1054 int response;
1055 byte_t rx[HITAG_FRAME_LEN];
1056 size_t rxlen=0;
1057 byte_t txbuf[HITAG_FRAME_LEN];
1058 byte_t* tx = txbuf;
1059 size_t txlen=0;
1060 int lastbit;
1061 bool bSkip;
1062 int reset_sof;
1063 int tag_sof;
1064 int t_wait = HITAG_T_WAIT_MAX;
1065 bool bStop;
1066 bool bQuitTraceFull = false;
1067
1068 // Clean up trace and prepare it for storing frames
1069 iso14a_set_tracing(TRUE);
1070 iso14a_clear_trace();
1071 DbpString("Starting Hitag reader family");
1072
1073 // Check configuration
1074 switch(htf) {
1075 case RHT2F_PASSWORD: {
1076 Dbprintf("List identifier in password mode");
1077 memcpy(password,htd->pwd.password,4);
1078 blocknr = 0;
1079 bQuitTraceFull = false;
1080 bQuiet = false;
1081 bPwd = false;
1082 } break;
1083
1084 case RHT2F_AUTHENTICATE: {
1085 DbpString("Authenticating using nr,ar pair:");
1086 memcpy(NrAr,htd->auth.NrAr,8);
1087 Dbhexdump(8,NrAr,false);
1088 bQuiet = false;
1089 bCrypto = false;
1090 bAuthenticating = false;
1091 bQuitTraceFull = true;
1092 } break;
1093
1094 case RHT2F_CRYPTO: {
1095 DbpString("Authenticating using key:");
1096 memcpy(key,htd->crypto.key,6);
1097 Dbhexdump(6,key,false);
1098 blocknr = 0;
1099 bQuiet = false;
1100 bCrypto = false;
1101 bAuthenticating = false;
1102 bQuitTraceFull = true;
1103 } break;
1104
1105 case RHT2F_TEST_AUTH_ATTEMPTS: {
1106 Dbprintf("Testing %d authentication attempts",(auth_table_len/8));
1107 auth_table_pos = 0;
1108 memcpy(NrAr,auth_table,8);
1109 bQuitTraceFull = false;
1110 bQuiet = false;
1111 bCrypto = false;
1112 } break;
1113
1114 default: {
1115 Dbprintf("Error, unknown function: %d",htf);
1116 return;
1117 } break;
1118 }
1119
1120 LED_D_ON();
1121 hitag2_init();
1122
1123 // Configure output and enable pin that is connected to the FPGA (for modulating)
1124 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
1125 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
1126
1127 // Set fpga in edge detect with reader field, we can modulate as reader now
1128 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
1129
1130 // Set Frequency divisor which will drive the FPGA and analog mux selection
1131 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
1132 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
1133 RELAY_OFF();
1134
1135 // Disable modulation at default, which means enable the field
1136 LOW(GPIO_SSC_DOUT);
1137
1138 // Give it a bit of time for the resonant antenna to settle.
1139 SpinDelay(30);
1140
1141 // Enable Peripheral Clock for TIMER_CLOCK0, used to measure exact timing before answering
1142 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
1143
1144 // Enable Peripheral Clock for TIMER_CLOCK1, used to capture edges of the tag frames
1145 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
1146 AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
1147
1148 // Disable timer during configuration
1149 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1150
1151 // Capture mode, defaul timer source = MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
1152 // external trigger rising edge, load RA on falling edge of TIOA.
1153 AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK | AT91C_TC_ETRGEDG_FALLING | AT91C_TC_ABETRG | AT91C_TC_LDRA_FALLING;
1154
1155 // Enable and reset counters
1156 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1157 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1158
1159 // Reset the received frame, frame count and timing info
1160 frame_count = 0;
1161 response = 0;
1162 lastbit = 1;
1163 bStop = false;
1164
1165 // Tag specific configuration settings (sof, timings, etc.)
1166 if (htf < 10){
1167 // hitagS settings
1168 reset_sof = 1;
1169 t_wait = 200;
1170 DbpString("Configured for hitagS reader");
1171 } else if (htf < 20) {
1172 // hitag1 settings
1173 reset_sof = 1;
1174 t_wait = 200;
1175 DbpString("Configured for hitag1 reader");
1176 } else if (htf < 30) {
1177 // hitag2 settings
1178 reset_sof = 4;
1179 t_wait = HITAG_T_WAIT_2;
1180 DbpString("Configured for hitag2 reader");
1181 } else {
1182 Dbprintf("Error, unknown hitag reader type: %d",htf);
1183 return;
1184 }
1185
1186 while(!bStop && !BUTTON_PRESS()) {
1187 // Watchdog hit
1188 WDT_HIT();
1189
1190 // Check if frame was captured and store it
1191 if(rxlen > 0) {
1192 frame_count++;
1193 if (!bQuiet) {
1194 if (!LogTrace(rx,nbytes(rxlen),response,0,false)) {
1195 DbpString("Trace full");
1196 if (bQuitTraceFull) {
1197 break;
1198 } else {
1199 bQuiet = true;
1200 }
1201 }
1202 }
1203 }
1204
1205 // By default reset the transmission buffer
1206 tx = txbuf;
1207 switch(htf) {
1208 case RHT2F_PASSWORD: {
1209 bStop = !hitag2_password(rx,rxlen,tx,&txlen);
1210 } break;
1211 case RHT2F_AUTHENTICATE: {
1212 bStop = !hitag2_authenticate(rx,rxlen,tx,&txlen);
1213 } break;
1214 case RHT2F_CRYPTO: {
1215 bStop = !hitag2_crypto(rx,rxlen,tx,&txlen);
1216 } break;
1217 case RHT2F_TEST_AUTH_ATTEMPTS: {
1218 bStop = !hitag2_test_auth_attempts(rx,rxlen,tx,&txlen);
1219 } break;
1220 default: {
1221 Dbprintf("Error, unknown function: %d",htf);
1222 return;
1223 } break;
1224 }
1225
1226 // Send and store the reader command
1227 // Disable timer 1 with external trigger to avoid triggers during our own modulation
1228 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1229
1230 // Wait for HITAG_T_WAIT_2 carrier periods after the last tag bit before transmitting,
1231 // Since the clock counts since the last falling edge, a 'one' means that the
1232 // falling edge occured halfway the period. with respect to this falling edge,
1233 // we need to wait (T_Wait2 + half_tag_period) when the last was a 'one'.
1234 // All timer values are in terms of T0 units
1235 while(AT91C_BASE_TC0->TC_CV < T0*(t_wait+(HITAG_T_TAG_HALF_PERIOD*lastbit)));
1236
1237 // Transmit the reader frame
1238 hitag_reader_send_frame(tx,txlen);
1239
1240 // Enable and reset external trigger in timer for capturing future frames
1241 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
1242
1243 // Add transmitted frame to total count
1244 if(txlen > 0) {
1245 frame_count++;
1246 if (!bQuiet) {
1247 // Store the frame in the trace
1248 if (!LogTrace(tx,nbytes(txlen),HITAG_T_WAIT_2,0,true)) {
1249 if (bQuitTraceFull) {
1250 break;
1251 } else {
1252 bQuiet = true;
1253 }
1254 }
1255 }
1256 }
1257
1258 // Reset values for receiving frames
1259 memset(rx,0x00,sizeof(rx));
1260 rxlen = 0;
1261 lastbit = 1;
1262 bSkip = true;
1263 tag_sof = reset_sof;
1264 response = 0;
1265
1266 // Receive frame, watch for at most T0*EOF periods
1267 while (AT91C_BASE_TC1->TC_CV < T0*HITAG_T_WAIT_MAX) {
1268 // Check if falling edge in tag modulation is detected
1269 if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
1270 // Retrieve the new timing values
1271 int ra = (AT91C_BASE_TC1->TC_RA/T0);
1272
1273 // Reset timer every frame, we have to capture the last edge for timing
1274 AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
1275
1276 LED_B_ON();
1277
1278 // Capture tag frame (manchester decoding using only falling edges)
1279 if(ra >= HITAG_T_EOF) {
1280 if (rxlen != 0) {
1281 //DbpString("wierd1?");
1282 }
1283 // Capture the T0 periods that have passed since last communication or field drop (reset)
1284 // We always recieve a 'one' first, which has the falling edge after a half period |-_|
1285 response = ra-HITAG_T_TAG_HALF_PERIOD;
1286 } else if(ra >= HITAG_T_TAG_CAPTURE_FOUR_HALF) {
1287 // Manchester coding example |-_|_-|-_| (101)
1288 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1289 rxlen++;
1290 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1291 rxlen++;
1292 } else if(ra >= HITAG_T_TAG_CAPTURE_THREE_HALF) {
1293 // Manchester coding example |_-|...|_-|-_| (0...01)
1294 rx[rxlen / 8] |= 0 << (7-(rxlen%8));
1295 rxlen++;
1296 // We have to skip this half period at start and add the 'one' the second time
1297 if (!bSkip) {
1298 rx[rxlen / 8] |= 1 << (7-(rxlen%8));
1299 rxlen++;
1300 }
1301 lastbit = !lastbit;
1302 bSkip = !bSkip;
1303 } else if(ra >= HITAG_T_TAG_CAPTURE_TWO_HALF) {
1304 // Manchester coding example |_-|_-| (00) or |-_|-_| (11)
1305 if (tag_sof) {
1306 // Ignore bits that are transmitted during SOF
1307 tag_sof--;
1308 } else {
1309 // bit is same as last bit
1310 rx[rxlen / 8] |= lastbit << (7-(rxlen%8));
1311 rxlen++;
1312 }
1313 } else {
1314 // Ignore wierd value, is to small to mean anything
1315 }
1316 }
1317
1318 // We can break this loop if we received the last bit from a frame
1319 if (AT91C_BASE_TC1->TC_CV > T0*HITAG_T_EOF) {
1320 if (rxlen>0) break;
1321 }
1322 }
1323 }
1324 LED_B_OFF();
1325 LED_D_OFF();
1326 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
1327 AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
1328 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1329
1330 // Dbprintf("frame received: %d",frame_count);
1331 // DbpString("All done");
1332 }
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