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ADD: a markdown file for the readme.txt file. I want to be able to show the build...
[proxmark3-svn] / armsrc / crapto1.c
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20f9a2a1
M		 1/* crapto1.c\r
2\r
3 This program is free software; you can redistribute it and/or\r
4 modify it under the terms of the GNU General Public License\r
5 as published by the Free Software Foundation; either version 2\r
6 of the License, or (at your option) any later version.\r
7\r
8 This program is distributed in the hope that it will be useful,\r
9 but WITHOUT ANY WARRANTY; without even the implied warranty of\r
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\r
11 GNU General Public License for more details.\r
12\r
13 You should have received a copy of the GNU General Public License\r
14 along with this program; if not, write to the Free Software\r
15 Foundation, Inc., 51 Franklin Street, Fifth Floor,\r
16 Boston, MA 02110-1301, US$\r
17\r
18 Copyright (C) 2008-2008 bla <blapost@gmail.com>\r
19*/\r
20#include "crapto1.h"\r
21#include <stdlib.h>\r
22\r
23#if !defined LOWMEM && defined __GNUC__\r
24static uint8_t filterlut[1 << 20];\r
25static void __attribute__((constructor)) fill_lut()\r
26{\r
27 uint32_t i;\r
28 for(i = 0; i < 1 << 20; ++i)\r
29 filterlut[i] = filter(i);\r
30}\r
31#define filter(x) (filterlut[(x) & 0xfffff])\r
32#endif\r
33\r
34static void quicksort(uint32_t* const start, uint32_t* const stop)\r
35{\r
36 uint32_t *it = start + 1, *rit = stop;\r
9cefee6f 37 uint32_t tmp;\r
20f9a2a1
M		 38\r
39 if(it > rit)\r
40 return;\r
41\r
42 while(it < rit)\r
43 if(*it <= *start)\r
44 ++it;\r
45 else if(*rit > *start)\r
46 --rit;\r
9cefee6f 47 else {\r
48 tmp = *it;\r
49 *it = *rit;\r
50 *rit = tmp;\r
51 }\r
20f9a2a1
M		 52\r
53 if(*rit >= *start)\r
54 --rit;\r
9cefee6f 55 if(rit != start) {\r
56 tmp = *rit;\r
57 *rit = *start;\r
58 *start = tmp;\r
59 }\r
20f9a2a1
M		 60\r
61 quicksort(start, rit - 1);\r
62 quicksort(rit + 1, stop);\r
63}\r
64/** binsearch\r
65 * Binary search for the first occurence of *stop's MSB in sorted [start,stop]\r
66 */\r
67static inline uint32_t* binsearch(uint32_t *start, uint32_t *stop)\r
68{\r
69 uint32_t mid, val = *stop & 0xff000000;\r
70 while(start != stop)\r
71 if(start[mid = (stop - start) >> 1] > val)\r
72 stop = &start[mid];\r
73 else\r
74 start += mid + 1;\r
75\r
76 return start;\r
77}\r
78\r
79/** update_contribution\r
80 * helper, calculates the partial linear feedback contributions and puts in MSB\r
81 */\r
82static inline void\r
83update_contribution(uint32_t *item, const uint32_t mask1, const uint32_t mask2)\r
84{\r
85 uint32_t p = *item >> 25;\r
86\r
87 p = p << 1 | parity(*item & mask1);\r
88 p = p << 1 | parity(*item & mask2);\r
89 *item = p << 24 | (*item & 0xffffff);\r
90}\r
91\r
92/** extend_table\r
93 * using a bit of the keystream extend the table of possible lfsr states\r
94 */\r
c2d2a5a6 95static inline void extend_table(uint32_t *tbl, uint32_t **end, int bit, int m1, int m2, uint32_t in)\r
20f9a2a1
M		 96{\r
97 in <<= 24;\r
98 for(*tbl <<= 1; tbl <= *end; *++tbl <<= 1)\r
99 if(filter(*tbl) ^ filter(*tbl | 1)) {\r
100 *tbl |= filter(*tbl) ^ bit;\r
101 update_contribution(tbl, m1, m2);\r
102 *tbl ^= in;\r
103 } else if(filter(*tbl) == bit) {\r
104 *++*end = tbl[1];\r
105 tbl[1] = tbl[0] | 1;\r
106 update_contribution(tbl, m1, m2);\r
107 *tbl++ ^= in;\r
108 update_contribution(tbl, m1, m2);\r
109 *tbl ^= in;\r
110 } else\r
111 *tbl-- = *(*end)--;\r
112}\r
113/** extend_table_simple\r
114 * using a bit of the keystream extend the table of possible lfsr states\r
115 */\r
116static inline void extend_table_simple(uint32_t *tbl, uint32_t **end, int bit)\r
117{\r
118 for(*tbl <<= 1; tbl <= *end; *++tbl <<= 1)\r
119 if(filter(*tbl) ^ filter(*tbl | 1))\r
120 *tbl |= filter(*tbl) ^ bit;\r
121 else if(filter(*tbl) == bit) {\r
122 *++*end = *++tbl;\r
123 *tbl = tbl[-1] | 1;\r
124 } else\r
125 *tbl-- = *(*end)--;\r
126}\r
127/** recover\r
128 * recursively narrow down the search space, 4 bits of keystream at a time\r
129 */\r
130static struct Crypto1State*\r
131recover(uint32_t *o_head, uint32_t *o_tail, uint32_t oks,\r
132 uint32_t *e_head, uint32_t *e_tail, uint32_t eks, int rem,\r
133 struct Crypto1State *sl, uint32_t in)\r
134{\r
135 uint32_t *o, *e, i;\r
136\r
137 if(rem == -1) {\r
138 for(e = e_head; e <= e_tail; ++e) {\r
139 *e = *e << 1 ^ parity(*e & LF_POLY_EVEN) ^ !!(in & 4);\r
140 for(o = o_head; o <= o_tail; ++o, ++sl) {\r
141 sl->even = *o;\r
142 sl->odd = *e ^ parity(*o & LF_POLY_ODD);\r
143 sl[1].odd = sl[1].even = 0;\r
144 }\r
145 }\r
146 return sl;\r
147 }\r
148\r
149 for(i = 0; i < 4 && rem--; i++) {\r
150 oks >>= 1;\r
151 eks >>= 1;\r
152 in >>= 2;\r
153 extend_table(o_head, &o_tail, oks & 1, LF_POLY_EVEN << 1 | 1,\r
154 LF_POLY_ODD << 1, 0);\r
155 if(o_head > o_tail)\r
156 return sl;\r
157\r
158 extend_table(e_head, &e_tail, eks & 1, LF_POLY_ODD,\r
159 LF_POLY_EVEN << 1 | 1, in & 3);\r
160 if(e_head > e_tail)\r
161 return sl;\r
162 }\r
163\r
164 quicksort(o_head, o_tail);\r
165 quicksort(e_head, e_tail);\r
166\r
167 while(o_tail >= o_head && e_tail >= e_head)\r
168 if(((*o_tail ^ *e_tail) >> 24) == 0) {\r
169 o_tail = binsearch(o_head, o = o_tail);\r
170 e_tail = binsearch(e_head, e = e_tail);\r
171 sl = recover(o_tail--, o, oks,\r
172 e_tail--, e, eks, rem, sl, in);\r
173 }\r
174 else if(*o_tail > *e_tail)\r
175 o_tail = binsearch(o_head, o_tail) - 1;\r
176 else\r
177 e_tail = binsearch(e_head, e_tail) - 1;\r
178\r
179 return sl;\r
180}\r
181/** lfsr_recovery\r
182 * recover the state of the lfsr given 32 bits of the keystream\r
183 * additionally you can use the in parameter to specify the value\r
184 * that was fed into the lfsr at the time the keystream was generated\r
185 */\r
186struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in)\r
187{\r
188 struct Crypto1State *statelist;\r
189 uint32_t *odd_head = 0, *odd_tail = 0, oks = 0;\r
190 uint32_t *even_head = 0, *even_tail = 0, eks = 0;\r
191 int i;\r
192\r
193 for(i = 31; i >= 0; i -= 2)\r
194 oks = oks << 1 | BEBIT(ks2, i);\r
195 for(i = 30; i >= 0; i -= 2)\r
196 eks = eks << 1 | BEBIT(ks2, i);\r
197\r
198 odd_head = odd_tail = malloc(sizeof(uint32_t) << 21);\r
199 even_head = even_tail = malloc(sizeof(uint32_t) << 21);\r
200 statelist = malloc(sizeof(struct Crypto1State) << 18);\r
201 if(!odd_tail-- || !even_tail-- || !statelist) {\r
202 free(statelist);\r
203 statelist = 0;\r
204 goto out;\r
205 }\r
206\r
207 statelist->odd = statelist->even = 0;\r
208\r
209 for(i = 1 << 20; i >= 0; --i) {\r
210 if(filter(i) == (oks & 1))\r
211 *++odd_tail = i;\r
212 if(filter(i) == (eks & 1))\r
213 *++even_tail = i;\r
214 }\r
215\r
216 for(i = 0; i < 4; i++) {\r
217 extend_table_simple(odd_head, &odd_tail, (oks >>= 1) & 1);\r
218 extend_table_simple(even_head, &even_tail, (eks >>= 1) & 1);\r
219 }\r
220\r
221 in = (in >> 16 & 0xff) | (in << 16) | (in & 0xff00);\r
222 recover(odd_head, odd_tail, oks,\r
223 even_head, even_tail, eks, 11, statelist, in << 1);\r
224\r
225out:\r
226 free(odd_head);\r
227 free(even_head);\r
228 return statelist;\r
229}\r
230\r
231static const uint32_t S1[] = { 0x62141, 0x310A0, 0x18850, 0x0C428, 0x06214,\r
232 0x0310A, 0x85E30, 0xC69AD, 0x634D6, 0xB5CDE, 0xDE8DA, 0x6F46D, 0xB3C83,\r
233 0x59E41, 0xA8995, 0xD027F, 0x6813F, 0x3409F, 0x9E6FA};\r
234static const uint32_t S2[] = { 0x3A557B00, 0x5D2ABD80, 0x2E955EC0, 0x174AAF60,\r
235 0x0BA557B0, 0x05D2ABD8, 0x0449DE68, 0x048464B0, 0x42423258, 0x278192A8,\r
236 0x156042D0, 0x0AB02168, 0x43F89B30, 0x61FC4D98, 0x765EAD48, 0x7D8FDD20,\r
237 0x7EC7EE90, 0x7F63F748, 0x79117020};\r
238static const uint32_t T1[] = {\r
239 0x4F37D, 0x279BE, 0x97A6A, 0x4BD35, 0x25E9A, 0x12F4D, 0x097A6, 0x80D66,\r
240 0xC4006, 0x62003, 0xB56B4, 0x5AB5A, 0xA9318, 0xD0F39, 0x6879C, 0xB057B,\r
241 0x582BD, 0x2C15E, 0x160AF, 0x8F6E2, 0xC3DC4, 0xE5857, 0x72C2B, 0x39615,\r
242 0x98DBF, 0xC806A, 0xE0680, 0x70340, 0x381A0, 0x98665, 0x4C332, 0xA272C};\r
243static const uint32_t T2[] = { 0x3C88B810, 0x5E445C08, 0x2982A580, 0x14C152C0,\r
244 0x4A60A960, 0x253054B0, 0x52982A58, 0x2FEC9EA8, 0x1156C4D0, 0x08AB6268,\r
245 0x42F53AB0, 0x217A9D58, 0x161DC528, 0x0DAE6910, 0x46D73488, 0x25CB11C0,\r
246 0x52E588E0, 0x6972C470, 0x34B96238, 0x5CFC3A98, 0x28DE96C8, 0x12CFC0E0,\r
247 0x4967E070, 0x64B3F038, 0x74F97398, 0x7CDC3248, 0x38CE92A0, 0x1C674950,\r
248 0x0E33A4A8, 0x01B959D0, 0x40DCACE8, 0x26CEDDF0};\r
249static const uint32_t C1[] = { 0x846B5, 0x4235A, 0x211AD};\r
250static const uint32_t C2[] = { 0x1A822E0, 0x21A822E0, 0x21A822E0};\r
251/** Reverse 64 bits of keystream into possible cipher states\r
252 * Variation mentioned in the paper. Somewhat optimized version\r
253 */\r
254struct Crypto1State* lfsr_recovery64(uint32_t ks2, uint32_t ks3)\r
255{\r
256 struct Crypto1State *statelist, *sl;\r
257 uint8_t oks[32], eks[32], hi[32];\r
258 uint32_t low = 0, win = 0;\r
259 uint32_t *tail, table[1 << 16];\r
260 int i, j;\r
261\r
262 sl = statelist = malloc(sizeof(struct Crypto1State) << 4);\r
263 if(!sl)\r
264 return 0;\r
265 sl->odd = sl->even = 0;\r
266\r
267 for(i = 30; i >= 0; i -= 2) {\r
268 oks[i >> 1] = BEBIT(ks2, i);\r
269 oks[16 + (i >> 1)] = BEBIT(ks3, i);\r
270 }\r
271 for(i = 31; i >= 0; i -= 2) {\r
272 eks[i >> 1] = BEBIT(ks2, i);\r
273 eks[16 + (i >> 1)] = BEBIT(ks3, i);\r
274 }\r
275\r
276 for(i = 0xfffff; i >= 0; --i) {\r
277 if (filter(i) != oks[0])\r
278 continue;\r
279\r
280 *(tail = table) = i;\r
281 for(j = 1; tail >= table && j < 29; ++j)\r
282 extend_table_simple(table, &tail, oks[j]);\r
283\r
284 if(tail < table)\r
285 continue;\r
286\r
287 for(j = 0; j < 19; ++j)\r
288 low = low << 1 | parity(i & S1[j]);\r
289 for(j = 0; j < 32; ++j)\r
290 hi[j] = parity(i & T1[j]);\r
291\r
292 for(; tail >= table; --tail) {\r
293 for(j = 0; j < 3; ++j) {\r
294 *tail = *tail << 1;\r
295 *tail |= parity((i & C1[j]) ^ (*tail & C2[j]));\r
296 if(filter(*tail) != oks[29 + j])\r
297 goto continue2;\r
298 }\r
299\r
300 for(j = 0; j < 19; ++j)\r
301 win = win << 1 | parity(*tail & S2[j]);\r
302\r
303 win ^= low;\r
304 for(j = 0; j < 32; ++j) {\r
305 win = win << 1 ^ hi[j] ^ parity(*tail & T2[j]);\r
306 if(filter(win) != eks[j])\r
307 goto continue2;\r
308 }\r
309\r
310 *tail = *tail << 1 | parity(LF_POLY_EVEN & *tail);\r
311 sl->odd = *tail ^ parity(LF_POLY_ODD & win);\r
312 sl->even = win;\r
313 ++sl;\r
314 sl->odd = sl->even = 0;\r
315 continue2:;\r
316 }\r
317 }\r
318 return statelist;\r
319}\r
320\r
321/** lfsr_rollback_bit\r
322 * Rollback the shift register in order to get previous states\r
323 */\r
324uint8_t lfsr_rollback_bit(struct Crypto1State *s, uint32_t in, int fb)\r
325{\r
326 int out;\r
327 uint8_t ret;\r
9cefee6f 328 uint32_t tmp;\r
20f9a2a1
M		 329\r
330 s->odd &= 0xffffff;\r
9cefee6f 331 tmp = s->odd;\r
332 s->odd = s->even;\r
333 s->even = tmp;\r
20f9a2a1
M		 334\r
335 out = s->even & 1;\r
336 out ^= LF_POLY_EVEN & (s->even >>= 1);\r
337 out ^= LF_POLY_ODD & s->odd;\r
338 out ^= !!in;\r
339 out ^= (ret = filter(s->odd)) & !!fb;\r
340\r
341 s->even |= parity(out) << 23;\r
342 return ret;\r
343}\r
344/** lfsr_rollback_byte\r
345 * Rollback the shift register in order to get previous states\r
346 */\r
347uint8_t lfsr_rollback_byte(struct Crypto1State *s, uint32_t in, int fb)\r
348{\r
c2d2a5a6 349/* int i, ret = 0;\r
20f9a2a1
M		 350 for (i = 7; i >= 0; --i)\r
351 ret |= lfsr_rollback_bit(s, BIT(in, i), fb) << i;\r
c2d2a5a6 352*/\r
353// unfold loop 20160112\r
354 uint8_t ret = 0;\r
355 ret |= lfsr_rollback_bit(s, BIT(in, 7), fb) << 7;\r
356 ret |= lfsr_rollback_bit(s, BIT(in, 6), fb) << 6;\r
357 ret |= lfsr_rollback_bit(s, BIT(in, 5), fb) << 5;\r
358 ret |= lfsr_rollback_bit(s, BIT(in, 4), fb) << 4;\r
359 ret |= lfsr_rollback_bit(s, BIT(in, 3), fb) << 3;\r
360 ret |= lfsr_rollback_bit(s, BIT(in, 2), fb) << 2;\r
361 ret |= lfsr_rollback_bit(s, BIT(in, 1), fb) << 1;\r
362 ret |= lfsr_rollback_bit(s, BIT(in, 0), fb) << 0;\r
20f9a2a1
M		 363 return ret;\r
364}\r
365/** lfsr_rollback_word\r
366 * Rollback the shift register in order to get previous states\r
367 */\r
368uint32_t lfsr_rollback_word(struct Crypto1State *s, uint32_t in, int fb)\r
369{\r
c2d2a5a6 370/* int i;\r
20f9a2a1
M		 371 uint32_t ret = 0;\r
372 for (i = 31; i >= 0; --i)\r
373 ret |= lfsr_rollback_bit(s, BEBIT(in, i), fb) << (i ^ 24);\r
c2d2a5a6 374*/\r
375// unfold loop 20160112\r
376 uint32_t ret = 0;\r
377 ret |= lfsr_rollback_bit(s, BEBIT(in, 31), fb) << (31 ^ 24);\r
378 ret |= lfsr_rollback_bit(s, BEBIT(in, 30), fb) << (30 ^ 24);\r
379 ret |= lfsr_rollback_bit(s, BEBIT(in, 29), fb) << (29 ^ 24);\r
380 ret |= lfsr_rollback_bit(s, BEBIT(in, 28), fb) << (28 ^ 24);\r
381 ret |= lfsr_rollback_bit(s, BEBIT(in, 27), fb) << (27 ^ 24);\r
382 ret |= lfsr_rollback_bit(s, BEBIT(in, 26), fb) << (26 ^ 24);\r
383 ret |= lfsr_rollback_bit(s, BEBIT(in, 25), fb) << (25 ^ 24);\r
384 ret |= lfsr_rollback_bit(s, BEBIT(in, 24), fb) << (24 ^ 24);\r
385\r
386 ret |= lfsr_rollback_bit(s, BEBIT(in, 23), fb) << (23 ^ 24);\r
387 ret |= lfsr_rollback_bit(s, BEBIT(in, 22), fb) << (22 ^ 24);\r
388 ret |= lfsr_rollback_bit(s, BEBIT(in, 21), fb) << (21 ^ 24);\r
389 ret |= lfsr_rollback_bit(s, BEBIT(in, 20), fb) << (20 ^ 24);\r
390 ret |= lfsr_rollback_bit(s, BEBIT(in, 19), fb) << (19 ^ 24);\r
391 ret |= lfsr_rollback_bit(s, BEBIT(in, 18), fb) << (18 ^ 24);\r
392 ret |= lfsr_rollback_bit(s, BEBIT(in, 17), fb) << (17 ^ 24);\r
393 ret |= lfsr_rollback_bit(s, BEBIT(in, 16), fb) << (16 ^ 24);\r
394\r
395 ret |= lfsr_rollback_bit(s, BEBIT(in, 15), fb) << (15 ^ 24);\r
396 ret |= lfsr_rollback_bit(s, BEBIT(in, 14), fb) << (14 ^ 24);\r
397 ret |= lfsr_rollback_bit(s, BEBIT(in, 13), fb) << (13 ^ 24);\r
398 ret |= lfsr_rollback_bit(s, BEBIT(in, 12), fb) << (12 ^ 24);\r
399 ret |= lfsr_rollback_bit(s, BEBIT(in, 11), fb) << (11 ^ 24);\r
400 ret |= lfsr_rollback_bit(s, BEBIT(in, 10), fb) << (10 ^ 24);\r
401 ret |= lfsr_rollback_bit(s, BEBIT(in, 9), fb) << (9 ^ 24);\r
402 ret |= lfsr_rollback_bit(s, BEBIT(in, 8), fb) << (8 ^ 24);\r
403\r
404 ret |= lfsr_rollback_bit(s, BEBIT(in, 7), fb) << (7 ^ 24);\r
405 ret |= lfsr_rollback_bit(s, BEBIT(in, 6), fb) << (6 ^ 24);\r
406 ret |= lfsr_rollback_bit(s, BEBIT(in, 5), fb) << (5 ^ 24);\r
407 ret |= lfsr_rollback_bit(s, BEBIT(in, 4), fb) << (4 ^ 24);\r
408 ret |= lfsr_rollback_bit(s, BEBIT(in, 3), fb) << (3 ^ 24);\r
409 ret |= lfsr_rollback_bit(s, BEBIT(in, 2), fb) << (2 ^ 24);\r
410 ret |= lfsr_rollback_bit(s, BEBIT(in, 1), fb) << (1 ^ 24);\r
411 ret |= lfsr_rollback_bit(s, BEBIT(in, 0), fb) << (0 ^ 24);\r
20f9a2a1
M		 412 return ret;\r
413}\r
414\r
415/** nonce_distance\r
416 * x,y valid tag nonces, then prng_successor(x, nonce_distance(x, y)) = y\r
417 */\r
418static uint16_t *dist = 0;\r
419int nonce_distance(uint32_t from, uint32_t to)\r
420{\r
421 uint16_t x, i;\r
422 if(!dist) {\r
423 dist = malloc(2 << 16);\r
424 if(!dist)\r
425 return -1;\r
426 for (x = i = 1; i; ++i) {\r
427 dist[(x & 0xff) << 8 | x >> 8] = i;\r
428 x = x >> 1 | (x ^ x >> 2 ^ x >> 3 ^ x >> 5) << 15;\r
429 }\r
430 }\r
431 return (65535 + dist[to >> 16] - dist[from >> 16]) % 65535;\r
432}\r
433\r
434\r
435static uint32_t fastfwd[2][8] = {\r
436 { 0, 0x4BC53, 0xECB1, 0x450E2, 0x25E29, 0x6E27A, 0x2B298, 0x60ECB},\r
437 { 0, 0x1D962, 0x4BC53, 0x56531, 0xECB1, 0x135D3, 0x450E2, 0x58980}};\r
438/** lfsr_prefix_ks\r
439 *\r
440 * Is an exported helper function from the common prefix attack\r
441 * Described in the "dark side" paper. It returns an -1 terminated array\r
442 * of possible partial(21 bit) secret state.\r
443 * The required keystream(ks) needs to contain the keystream that was used to\r
444 * encrypt the NACK which is observed when varying only the 3 last bits of Nr\r
445 * only correct iff [NR_3] ^ NR_3 does not depend on Nr_3\r
446 */\r
447uint32_t *lfsr_prefix_ks(uint8_t ks[8], int isodd)\r
448{\r
449 uint32_t c, entry, *candidates = malloc(4 << 10);\r
450 int i, size = 0, good;\r
451\r
452 if(!candidates)\r
453 return 0;\r
454\r
455 for(i = 0; i < 1 << 21; ++i) {\r
456 for(c = 0, good = 1; good && c < 8; ++c) {\r
457 entry = i ^ fastfwd[isodd][c];\r
458 good &= (BIT(ks[c], isodd) == filter(entry >> 1));\r
459 good &= (BIT(ks[c], isodd + 2) == filter(entry));\r
460 }\r
461 if(good)\r
462 candidates[size++] = i;\r
463 }\r
464\r
465 candidates[size] = -1;\r
466\r
467 return candidates;\r
468}\r
469\r
470/** check_pfx_parity\r
471 * helper function which eliminates possible secret states using parity bits\r
472 */\r
473static struct Crypto1State*\r
474check_pfx_parity(uint32_t prefix, uint32_t rresp, uint8_t parities[8][8],\r
475 uint32_t odd, uint32_t even, struct Crypto1State* sl)\r
476{\r
477 uint32_t ks1, nr, ks2, rr, ks3, c, good = 1;\r
478\r
479 for(c = 0; good && c < 8; ++c) {\r
480 sl->odd = odd ^ fastfwd[1][c];\r
481 sl->even = even ^ fastfwd[0][c];\r
482\r
483 lfsr_rollback_bit(sl, 0, 0);\r
484 lfsr_rollback_bit(sl, 0, 0);\r
485\r
486 ks3 = lfsr_rollback_bit(sl, 0, 0);\r
487 ks2 = lfsr_rollback_word(sl, 0, 0);\r
488 ks1 = lfsr_rollback_word(sl, prefix | c << 5, 1);\r
489\r
490 nr = ks1 ^ (prefix | c << 5);\r
491 rr = ks2 ^ rresp;\r
492\r
493 good &= parity(nr & 0x000000ff) ^ parities[c][3] ^ BIT(ks2, 24);\r
494 good &= parity(rr & 0xff000000) ^ parities[c][4] ^ BIT(ks2, 16);\r
495 good &= parity(rr & 0x00ff0000) ^ parities[c][5] ^ BIT(ks2, 8);\r
496 good &= parity(rr & 0x0000ff00) ^ parities[c][6] ^ BIT(ks2, 0);\r
497 good &= parity(rr & 0x000000ff) ^ parities[c][7] ^ ks3;\r
498 }\r
499\r
500 return sl + good;\r
9cefee6f 501}\r
20f9a2a1
M		 502\r
503\r
504/** lfsr_common_prefix\r
505 * Implentation of the common prefix attack.\r
506 */\r
507struct Crypto1State*\r
508lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8], uint8_t par[8][8])\r
509{\r
510 struct Crypto1State *statelist, *s;\r
511 uint32_t *odd, *even, *o, *e, top;\r
512\r
513 odd = lfsr_prefix_ks(ks, 1);\r
514 even = lfsr_prefix_ks(ks, 0);\r
f6c18637 515 \r
20f9a2a1
M		 516 s = statelist = malloc((sizeof *statelist) << 20);\r
517 if(!s || !odd || !even) {\r
518 free(statelist);\r
519 statelist = 0;\r
c2d2a5a6 520 goto out;\r
20f9a2a1
M		 521 }\r
522\r
523 for(o = odd; *o + 1; ++o)\r
524 for(e = even; *e + 1; ++e)\r
525 for(top = 0; top < 64; ++top) {\r
526 *o += 1 << 21;\r
527 *e += (!(top & 7) + 1) << 21;\r
528 s = check_pfx_parity(pfx, rr, par, *o, *e, s);\r
529 }\r
530\r
531 s->odd = s->even = 0;\r
532out:\r
533 free(odd);\r
534 free(even);\r
535 return statelist;\r
536}\r
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