| 1 | /* crapto1.c |
| 2 | |
| 3 | This program is free software; you can redistribute it and/or |
| 4 | modify it under the terms of the GNU General Public License |
| 5 | as published by the Free Software Foundation; either version 2 |
| 6 | of the License, or (at your option) any later version. |
| 7 | |
| 8 | This program is distributed in the hope that it will be useful, |
| 9 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | GNU General Public License for more details. |
| 12 | |
| 13 | You should have received a copy of the GNU General Public License |
| 14 | along with this program; if not, write to the Free Software |
| 15 | Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 16 | Boston, MA 02110-1301, US$ |
| 17 | |
| 18 | Copyright (C) 2008-2014 bla <blapost@gmail.com> |
| 19 | */ |
| 20 | #include "crapto1.h" |
| 21 | |
| 22 | #include <stdlib.h> |
| 23 | #include "parity.h" |
| 24 | |
| 25 | #if !defined LOWMEM && defined __GNUC__ |
| 26 | static uint8_t filterlut[1 << 20]; |
| 27 | static void __attribute__((constructor)) fill_lut() |
| 28 | { |
| 29 | uint32_t i; |
| 30 | for(i = 0; i < 1 << 20; ++i) |
| 31 | filterlut[i] = filter(i); |
| 32 | } |
| 33 | #define filter(x) (filterlut[(x) & 0xfffff]) |
| 34 | #endif |
| 35 | |
| 36 | |
| 37 | |
| 38 | typedef struct bucket { |
| 39 | uint32_t *head; |
| 40 | uint32_t *bp; |
| 41 | } bucket_t; |
| 42 | |
| 43 | typedef bucket_t bucket_array_t[2][0x100]; |
| 44 | |
| 45 | typedef struct bucket_info { |
| 46 | struct { |
| 47 | uint32_t *head, *tail; |
| 48 | } bucket_info[2][0x100]; |
| 49 | uint32_t numbuckets; |
| 50 | } bucket_info_t; |
| 51 | |
| 52 | |
| 53 | static void bucket_sort_intersect(uint32_t* const estart, uint32_t* const estop, |
| 54 | uint32_t* const ostart, uint32_t* const ostop, |
| 55 | bucket_info_t *bucket_info, bucket_array_t bucket) |
| 56 | { |
| 57 | uint32_t *p1, *p2; |
| 58 | uint32_t *start[2]; |
| 59 | uint32_t *stop[2]; |
| 60 | |
| 61 | start[0] = estart; |
| 62 | stop[0] = estop; |
| 63 | start[1] = ostart; |
| 64 | stop[1] = ostop; |
| 65 | |
| 66 | // init buckets to be empty |
| 67 | for (uint32_t i = 0; i < 2; i++) { |
| 68 | for (uint32_t j = 0x00; j <= 0xff; j++) { |
| 69 | bucket[i][j].bp = bucket[i][j].head; |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | // sort the lists into the buckets based on the MSB (contribution bits) |
| 74 | for (uint32_t i = 0; i < 2; i++) { |
| 75 | for (p1 = start[i]; p1 <= stop[i]; p1++) { |
| 76 | uint32_t bucket_index = (*p1 & 0xff000000) >> 24; |
| 77 | *(bucket[i][bucket_index].bp++) = *p1; |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | |
| 82 | // write back intersecting buckets as sorted list. |
| 83 | // fill in bucket_info with head and tail of the bucket contents in the list and number of non-empty buckets. |
| 84 | uint32_t nonempty_bucket; |
| 85 | for (uint32_t i = 0; i < 2; i++) { |
| 86 | p1 = start[i]; |
| 87 | nonempty_bucket = 0; |
| 88 | for (uint32_t j = 0x00; j <= 0xff; j++) { |
| 89 | if (bucket[0][j].bp != bucket[0][j].head && bucket[1][j].bp != bucket[1][j].head) { // non-empty intersecting buckets only |
| 90 | bucket_info->bucket_info[i][nonempty_bucket].head = p1; |
| 91 | for (p2 = bucket[i][j].head; p2 < bucket[i][j].bp; *p1++ = *p2++); |
| 92 | bucket_info->bucket_info[i][nonempty_bucket].tail = p1 - 1; |
| 93 | nonempty_bucket++; |
| 94 | } |
| 95 | } |
| 96 | bucket_info->numbuckets = nonempty_bucket; |
| 97 | } |
| 98 | } |
| 99 | /** binsearch |
| 100 | * Binary search for the first occurence of *stop's MSB in sorted [start,stop] |
| 101 | */ |
| 102 | /* static inline uint32_t* binsearch(uint32_t *start, uint32_t *stop) |
| 103 | { |
| 104 | uint32_t mid, val = *stop & 0xff000000; |
| 105 | while(start != stop) |
| 106 | if(start[mid = (stop - start) >> 1] > val) |
| 107 | stop = &start[mid]; |
| 108 | else |
| 109 | start += mid + 1; |
| 110 | |
| 111 | return start; |
| 112 | } |
| 113 | */ |
| 114 | /** update_contribution |
| 115 | * helper, calculates the partial linear feedback contributions and puts in MSB |
| 116 | */ |
| 117 | static inline void |
| 118 | update_contribution(uint32_t *item, const uint32_t mask1, const uint32_t mask2) |
| 119 | { |
| 120 | uint32_t p = *item >> 25; |
| 121 | |
| 122 | p = p << 1 | evenparity32(*item & mask1); |
| 123 | p = p << 1 | evenparity32(*item & mask2); |
| 124 | *item = p << 24 | (*item & 0xffffff); |
| 125 | } |
| 126 | |
| 127 | /** extend_table |
| 128 | * using a bit of the keystream extend the table of possible lfsr states |
| 129 | */ |
| 130 | static inline void |
| 131 | extend_table(uint32_t *tbl, uint32_t **end, int bit, int m1, int m2, uint32_t in) |
| 132 | { |
| 133 | in <<= 24; |
| 134 | for(*tbl <<= 1; tbl <= *end; *++tbl <<= 1) |
| 135 | if(filter(*tbl) ^ filter(*tbl | 1)) { |
| 136 | *tbl |= filter(*tbl) ^ bit; |
| 137 | update_contribution(tbl, m1, m2); |
| 138 | *tbl ^= in; |
| 139 | } else if(filter(*tbl) == bit) { |
| 140 | *++*end = tbl[1]; |
| 141 | tbl[1] = tbl[0] | 1; |
| 142 | update_contribution(tbl, m1, m2); |
| 143 | *tbl++ ^= in; |
| 144 | update_contribution(tbl, m1, m2); |
| 145 | *tbl ^= in; |
| 146 | } else |
| 147 | *tbl-- = *(*end)--; |
| 148 | } |
| 149 | /** extend_table_simple |
| 150 | * using a bit of the keystream extend the table of possible lfsr states |
| 151 | */ |
| 152 | static inline void extend_table_simple(uint32_t *tbl, uint32_t **end, int bit) |
| 153 | { |
| 154 | for(*tbl <<= 1; tbl <= *end; *++tbl <<= 1) |
| 155 | if(filter(*tbl) ^ filter(*tbl | 1)) |
| 156 | *tbl |= filter(*tbl) ^ bit; |
| 157 | else if(filter(*tbl) == bit) { |
| 158 | *++*end = *++tbl; |
| 159 | *tbl = tbl[-1] | 1; |
| 160 | |
| 161 | } else |
| 162 | *tbl-- = *(*end)--; |
| 163 | } |
| 164 | |
| 165 | |
| 166 | /** recover |
| 167 | * recursively narrow down the search space, 4 bits of keystream at a time |
| 168 | */ |
| 169 | static struct Crypto1State* |
| 170 | recover(uint32_t *o_head, uint32_t *o_tail, uint32_t oks, |
| 171 | uint32_t *e_head, uint32_t *e_tail, uint32_t eks, int rem, |
| 172 | struct Crypto1State *sl, uint32_t in, bucket_array_t bucket) |
| 173 | { |
| 174 | uint32_t *o, *e, i; |
| 175 | bucket_info_t bucket_info; |
| 176 | |
| 177 | if(rem == -1) { |
| 178 | for(e = e_head; e <= e_tail; ++e) { |
| 179 | *e = *e << 1 ^ evenparity32(*e & LF_POLY_EVEN) ^ !!(in & 4); |
| 180 | for(o = o_head; o <= o_tail; ++o, ++sl) { |
| 181 | sl->even = *o; |
| 182 | sl->odd = *e ^ evenparity32(*o & LF_POLY_ODD); |
| 183 | sl[1].odd = sl[1].even = 0; |
| 184 | } |
| 185 | } |
| 186 | return sl; |
| 187 | } |
| 188 | |
| 189 | for(i = 0; i < 4 && rem--; i++) { |
| 190 | oks >>= 1; |
| 191 | eks >>= 1; |
| 192 | in >>= 2; |
| 193 | extend_table(o_head, &o_tail, oks & 1, LF_POLY_EVEN << 1 | 1, |
| 194 | LF_POLY_ODD << 1, 0); |
| 195 | if(o_head > o_tail) |
| 196 | return sl; |
| 197 | |
| 198 | extend_table(e_head, &e_tail, eks & 1, LF_POLY_ODD, |
| 199 | LF_POLY_EVEN << 1 | 1, in & 3); |
| 200 | if(e_head > e_tail) |
| 201 | return sl; |
| 202 | } |
| 203 | bucket_sort_intersect(e_head, e_tail, o_head, o_tail, &bucket_info, bucket); |
| 204 | |
| 205 | for (int i = bucket_info.numbuckets - 1; i >= 0; i--) { |
| 206 | sl = recover(bucket_info.bucket_info[1][i].head, bucket_info.bucket_info[1][i].tail, oks, |
| 207 | bucket_info.bucket_info[0][i].head, bucket_info.bucket_info[0][i].tail, eks, |
| 208 | rem, sl, in, bucket); |
| 209 | } |
| 210 | |
| 211 | return sl; |
| 212 | } |
| 213 | /** lfsr_recovery |
| 214 | * recover the state of the lfsr given 32 bits of the keystream |
| 215 | * additionally you can use the in parameter to specify the value |
| 216 | * that was fed into the lfsr at the time the keystream was generated |
| 217 | */ |
| 218 | struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in) |
| 219 | { |
| 220 | struct Crypto1State *statelist; |
| 221 | uint32_t *odd_head = 0, *odd_tail = 0, oks = 0; |
| 222 | uint32_t *even_head = 0, *even_tail = 0, eks = 0; |
| 223 | int i; |
| 224 | |
| 225 | for(i = 31; i >= 0; i -= 2) |
| 226 | oks = oks << 1 | BEBIT(ks2, i); |
| 227 | for(i = 30; i >= 0; i -= 2) |
| 228 | eks = eks << 1 | BEBIT(ks2, i); |
| 229 | |
| 230 | odd_head = odd_tail = malloc(sizeof(uint32_t) << 21); |
| 231 | even_head = even_tail = malloc(sizeof(uint32_t) << 21); |
| 232 | statelist = malloc(sizeof(struct Crypto1State) << 18); |
| 233 | if(!odd_tail-- || !even_tail-- || !statelist) { |
| 234 | free(statelist); |
| 235 | statelist = 0; |
| 236 | goto out; |
| 237 | } |
| 238 | statelist->odd = statelist->even = 0; |
| 239 | |
| 240 | // allocate memory for out of place bucket_sort |
| 241 | bucket_array_t bucket; |
| 242 | for (uint32_t i = 0; i < 2; i++) |
| 243 | for (uint32_t j = 0; j <= 0xff; j++) { |
| 244 | bucket[i][j].head = malloc(sizeof(uint32_t)<<14); |
| 245 | if (!bucket[i][j].head) { |
| 246 | goto out; |
| 247 | } |
| 248 | } |
| 249 | |
| 250 | |
| 251 | for(i = 1 << 20; i >= 0; --i) { |
| 252 | if(filter(i) == (oks & 1)) |
| 253 | *++odd_tail = i; |
| 254 | if(filter(i) == (eks & 1)) |
| 255 | *++even_tail = i; |
| 256 | } |
| 257 | |
| 258 | for(i = 0; i < 4; i++) { |
| 259 | extend_table_simple(odd_head, &odd_tail, (oks >>= 1) & 1); |
| 260 | extend_table_simple(even_head, &even_tail, (eks >>= 1) & 1); |
| 261 | } |
| 262 | |
| 263 | in = (in >> 16 & 0xff) | (in << 16) | (in & 0xff00); |
| 264 | recover(odd_head, odd_tail, oks, |
| 265 | even_head, even_tail, eks, 11, statelist, in << 1, bucket); |
| 266 | |
| 267 | out: |
| 268 | free(odd_head); |
| 269 | free(even_head); |
| 270 | for (uint32_t i = 0; i < 2; i++) |
| 271 | for (uint32_t j = 0; j <= 0xff; j++) |
| 272 | free(bucket[i][j].head); |
| 273 | |
| 274 | return statelist; |
| 275 | } |
| 276 | |
| 277 | static const uint32_t S1[] = { 0x62141, 0x310A0, 0x18850, 0x0C428, 0x06214, |
| 278 | 0x0310A, 0x85E30, 0xC69AD, 0x634D6, 0xB5CDE, 0xDE8DA, 0x6F46D, 0xB3C83, |
| 279 | 0x59E41, 0xA8995, 0xD027F, 0x6813F, 0x3409F, 0x9E6FA}; |
| 280 | static const uint32_t S2[] = { 0x3A557B00, 0x5D2ABD80, 0x2E955EC0, 0x174AAF60, |
| 281 | 0x0BA557B0, 0x05D2ABD8, 0x0449DE68, 0x048464B0, 0x42423258, 0x278192A8, |
| 282 | 0x156042D0, 0x0AB02168, 0x43F89B30, 0x61FC4D98, 0x765EAD48, 0x7D8FDD20, |
| 283 | 0x7EC7EE90, 0x7F63F748, 0x79117020}; |
| 284 | static const uint32_t T1[] = { |
| 285 | 0x4F37D, 0x279BE, 0x97A6A, 0x4BD35, 0x25E9A, 0x12F4D, 0x097A6, 0x80D66, |
| 286 | 0xC4006, 0x62003, 0xB56B4, 0x5AB5A, 0xA9318, 0xD0F39, 0x6879C, 0xB057B, |
| 287 | 0x582BD, 0x2C15E, 0x160AF, 0x8F6E2, 0xC3DC4, 0xE5857, 0x72C2B, 0x39615, |
| 288 | 0x98DBF, 0xC806A, 0xE0680, 0x70340, 0x381A0, 0x98665, 0x4C332, 0xA272C}; |
| 289 | static const uint32_t T2[] = { 0x3C88B810, 0x5E445C08, 0x2982A580, 0x14C152C0, |
| 290 | 0x4A60A960, 0x253054B0, 0x52982A58, 0x2FEC9EA8, 0x1156C4D0, 0x08AB6268, |
| 291 | 0x42F53AB0, 0x217A9D58, 0x161DC528, 0x0DAE6910, 0x46D73488, 0x25CB11C0, |
| 292 | 0x52E588E0, 0x6972C470, 0x34B96238, 0x5CFC3A98, 0x28DE96C8, 0x12CFC0E0, |
| 293 | 0x4967E070, 0x64B3F038, 0x74F97398, 0x7CDC3248, 0x38CE92A0, 0x1C674950, |
| 294 | 0x0E33A4A8, 0x01B959D0, 0x40DCACE8, 0x26CEDDF0}; |
| 295 | static const uint32_t C1[] = { 0x846B5, 0x4235A, 0x211AD}; |
| 296 | static const uint32_t C2[] = { 0x1A822E0, 0x21A822E0, 0x21A822E0}; |
| 297 | /** Reverse 64 bits of keystream into possible cipher states |
| 298 | * Variation mentioned in the paper. Somewhat optimized version |
| 299 | */ |
| 300 | struct Crypto1State* lfsr_recovery64(uint32_t ks2, uint32_t ks3) |
| 301 | { |
| 302 | struct Crypto1State *statelist, *sl; |
| 303 | uint8_t oks[32], eks[32], hi[32]; |
| 304 | uint32_t low = 0, win = 0; |
| 305 | uint32_t *tail, table[1 << 16]; |
| 306 | int i, j; |
| 307 | |
| 308 | sl = statelist = malloc(sizeof(struct Crypto1State) << 4); |
| 309 | if(!sl) |
| 310 | return 0; |
| 311 | sl->odd = sl->even = 0; |
| 312 | |
| 313 | for(i = 30; i >= 0; i -= 2) { |
| 314 | oks[i >> 1] = BEBIT(ks2, i); |
| 315 | oks[16 + (i >> 1)] = BEBIT(ks3, i); |
| 316 | } |
| 317 | for(i = 31; i >= 0; i -= 2) { |
| 318 | eks[i >> 1] = BEBIT(ks2, i); |
| 319 | eks[16 + (i >> 1)] = BEBIT(ks3, i); |
| 320 | } |
| 321 | |
| 322 | for(i = 0xfffff; i >= 0; --i) { |
| 323 | if (filter(i) != oks[0]) |
| 324 | continue; |
| 325 | |
| 326 | *(tail = table) = i; |
| 327 | for(j = 1; tail >= table && j < 29; ++j) |
| 328 | extend_table_simple(table, &tail, oks[j]); |
| 329 | |
| 330 | if(tail < table) |
| 331 | continue; |
| 332 | |
| 333 | for(j = 0; j < 19; ++j) |
| 334 | low = low << 1 | evenparity32(i & S1[j]); |
| 335 | for(j = 0; j < 32; ++j) |
| 336 | hi[j] = evenparity32(i & T1[j]); |
| 337 | |
| 338 | for(; tail >= table; --tail) { |
| 339 | for(j = 0; j < 3; ++j) { |
| 340 | *tail = *tail << 1; |
| 341 | *tail |= evenparity32((i & C1[j]) ^ (*tail & C2[j])); |
| 342 | if(filter(*tail) != oks[29 + j]) |
| 343 | goto continue2; |
| 344 | } |
| 345 | |
| 346 | for(j = 0; j < 19; ++j) |
| 347 | win = win << 1 | evenparity32(*tail & S2[j]); |
| 348 | |
| 349 | win ^= low; |
| 350 | for(j = 0; j < 32; ++j) { |
| 351 | win = win << 1 ^ hi[j] ^ evenparity32(*tail & T2[j]); |
| 352 | if(filter(win) != eks[j]) |
| 353 | goto continue2; |
| 354 | } |
| 355 | |
| 356 | *tail = *tail << 1 | evenparity32(LF_POLY_EVEN & *tail); |
| 357 | sl->odd = *tail ^ evenparity32(LF_POLY_ODD & win); |
| 358 | sl->even = win; |
| 359 | ++sl; |
| 360 | sl->odd = sl->even = 0; |
| 361 | continue2:; |
| 362 | } |
| 363 | } |
| 364 | return statelist; |
| 365 | } |
| 366 | |
| 367 | /** lfsr_rollback_bit |
| 368 | * Rollback the shift register in order to get previous states |
| 369 | */ |
| 370 | uint8_t lfsr_rollback_bit(struct Crypto1State *s, uint32_t in, int fb) |
| 371 | { |
| 372 | int out; |
| 373 | uint8_t ret; |
| 374 | uint32_t t; |
| 375 | |
| 376 | s->odd &= 0xffffff; |
| 377 | t = s->odd, s->odd = s->even, s->even = t; |
| 378 | |
| 379 | out = s->even & 1; |
| 380 | out ^= LF_POLY_EVEN & (s->even >>= 1); |
| 381 | out ^= LF_POLY_ODD & s->odd; |
| 382 | out ^= !!in; |
| 383 | out ^= (ret = filter(s->odd)) & !!fb; |
| 384 | |
| 385 | s->even |= evenparity32(out) << 23; |
| 386 | return ret; |
| 387 | } |
| 388 | /** lfsr_rollback_byte |
| 389 | * Rollback the shift register in order to get previous states |
| 390 | */ |
| 391 | uint8_t lfsr_rollback_byte(struct Crypto1State *s, uint32_t in, int fb) |
| 392 | { |
| 393 | int i, ret=0; |
| 394 | for (i = 7; i >= 0; --i) |
| 395 | ret |= lfsr_rollback_bit(s, BIT(in, i), fb) << i; |
| 396 | return ret; |
| 397 | } |
| 398 | /** lfsr_rollback_word |
| 399 | * Rollback the shift register in order to get previous states |
| 400 | */ |
| 401 | uint32_t lfsr_rollback_word(struct Crypto1State *s, uint32_t in, int fb) |
| 402 | { |
| 403 | int i; |
| 404 | uint32_t ret = 0; |
| 405 | for (i = 31; i >= 0; --i) |
| 406 | ret |= lfsr_rollback_bit(s, BEBIT(in, i), fb) << (i ^ 24); |
| 407 | return ret; |
| 408 | } |
| 409 | |
| 410 | /** nonce_distance |
| 411 | * x,y valid tag nonces, then prng_successor(x, nonce_distance(x, y)) = y |
| 412 | */ |
| 413 | static uint16_t *dist = 0; |
| 414 | int nonce_distance(uint32_t from, uint32_t to) |
| 415 | { |
| 416 | uint16_t x, i; |
| 417 | if(!dist) { |
| 418 | dist = malloc(2 << 16); |
| 419 | if(!dist) |
| 420 | return -1; |
| 421 | for (x = i = 1; i; ++i) { |
| 422 | dist[(x & 0xff) << 8 | x >> 8] = i; |
| 423 | x = x >> 1 | (x ^ x >> 2 ^ x >> 3 ^ x >> 5) << 15; |
| 424 | } |
| 425 | } |
| 426 | return (65535 + dist[to >> 16] - dist[from >> 16]) % 65535; |
| 427 | } |
| 428 | |
| 429 | static uint32_t fastfwd[2][8] = { |
| 430 | { 0, 0x4BC53, 0xECB1, 0x450E2, 0x25E29, 0x6E27A, 0x2B298, 0x60ECB}, |
| 431 | { 0, 0x1D962, 0x4BC53, 0x56531, 0xECB1, 0x135D3, 0x450E2, 0x58980}}; |
| 432 | /** lfsr_prefix_ks |
| 433 | * |
| 434 | * Is an exported helper function from the common prefix attack |
| 435 | * Described in the "dark side" paper. It returns an -1 terminated array |
| 436 | * of possible partial(21 bit) secret state. |
| 437 | * The required keystream(ks) needs to contain the keystream that was used to |
| 438 | * encrypt the NACK which is observed when varying only the 3 last bits of Nr |
| 439 | * only correct iff [NR_3] ^ NR_3 does not depend on Nr_3 |
| 440 | */ |
| 441 | uint32_t *lfsr_prefix_ks(uint8_t ks[8], int isodd) |
| 442 | { |
| 443 | uint32_t c, entry, *candidates = malloc(4 << 10); |
| 444 | int i, size = 0, good; |
| 445 | |
| 446 | if(!candidates) |
| 447 | return 0; |
| 448 | |
| 449 | for(i = 0; i < 1 << 21; ++i) { |
| 450 | for(c = 0, good = 1; good && c < 8; ++c) { |
| 451 | entry = i ^ fastfwd[isodd][c]; |
| 452 | good &= (BIT(ks[c], isodd) == filter(entry >> 1)); |
| 453 | good &= (BIT(ks[c], isodd + 2) == filter(entry)); |
| 454 | } |
| 455 | if(good) |
| 456 | candidates[size++] = i; |
| 457 | } |
| 458 | |
| 459 | candidates[size] = -1; |
| 460 | |
| 461 | return candidates; |
| 462 | } |
| 463 | |
| 464 | /** check_pfx_parity |
| 465 | * helper function which eliminates possible secret states using parity bits |
| 466 | */ |
| 467 | static struct Crypto1State* |
| 468 | check_pfx_parity(uint32_t prefix, uint32_t rresp, uint8_t parities[8][8], |
| 469 | uint32_t odd, uint32_t even, struct Crypto1State* sl, uint32_t no_par) |
| 470 | { |
| 471 | uint32_t ks1, nr, ks2, rr, ks3, c, good = 1; |
| 472 | |
| 473 | for(c = 0; good && c < 8; ++c) { |
| 474 | sl->odd = odd ^ fastfwd[1][c]; |
| 475 | sl->even = even ^ fastfwd[0][c]; |
| 476 | |
| 477 | lfsr_rollback_bit(sl, 0, 0); |
| 478 | lfsr_rollback_bit(sl, 0, 0); |
| 479 | |
| 480 | ks3 = lfsr_rollback_bit(sl, 0, 0); |
| 481 | ks2 = lfsr_rollback_word(sl, 0, 0); |
| 482 | ks1 = lfsr_rollback_word(sl, prefix | c << 5, 1); |
| 483 | |
| 484 | if (no_par) |
| 485 | break; |
| 486 | |
| 487 | nr = ks1 ^ (prefix | c << 5); |
| 488 | rr = ks2 ^ rresp; |
| 489 | |
| 490 | good &= evenparity32(nr & 0x000000ff) ^ parities[c][3] ^ BIT(ks2, 24); |
| 491 | good &= evenparity32(rr & 0xff000000) ^ parities[c][4] ^ BIT(ks2, 16); |
| 492 | good &= evenparity32(rr & 0x00ff0000) ^ parities[c][5] ^ BIT(ks2, 8); |
| 493 | good &= evenparity32(rr & 0x0000ff00) ^ parities[c][6] ^ BIT(ks2, 0); |
| 494 | good &= evenparity32(rr & 0x000000ff) ^ parities[c][7] ^ ks3; |
| 495 | } |
| 496 | |
| 497 | return sl + good; |
| 498 | } |
| 499 | |
| 500 | |
| 501 | /** lfsr_common_prefix |
| 502 | * Implentation of the common prefix attack. |
| 503 | */ |
| 504 | struct Crypto1State* |
| 505 | lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8], uint8_t par[8][8], uint32_t no_par) |
| 506 | { |
| 507 | struct Crypto1State *statelist, *s; |
| 508 | uint32_t *odd, *even, *o, *e, top; |
| 509 | |
| 510 | odd = lfsr_prefix_ks(ks, 1); |
| 511 | even = lfsr_prefix_ks(ks, 0); |
| 512 | |
| 513 | s = statelist = malloc((sizeof *statelist) << 22); // was << 20. Need more for no_par special attack. Enough??? |
| 514 | if(!s || !odd || !even) { |
| 515 | free(statelist); |
| 516 | statelist = 0; |
| 517 | goto out; |
| 518 | } |
| 519 | |
| 520 | for(o = odd; *o + 1; ++o) |
| 521 | for(e = even; *e + 1; ++e) |
| 522 | for(top = 0; top < 64; ++top) { |
| 523 | *o += 1 << 21; |
| 524 | *e += (!(top & 7) + 1) << 21; |
| 525 | s = check_pfx_parity(pfx, rr, par, *o, *e, s, no_par); |
| 526 | } |
| 527 | |
| 528 | s->odd = s->even = 0; |
| 529 | out: |
| 530 | free(odd); |
| 531 | free(even); |
| 532 | return statelist; |
| 533 | } |