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Commit | Line | Data |
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35b73a1f | 1 | /* |
4f22f405 | 2 | * Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved. |
65e81670 | 3 | * |
4f22f405 RS |
4 | * Licensed under the OpenSSL license (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy | |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
65e81670 | 8 | */ |
4f22f405 | 9 | |
7793f30e BM |
10 | /* ==================================================================== |
11 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. | |
12 | * Portions of this software developed by SUN MICROSYSTEMS, INC., | |
13 | * and contributed to the OpenSSL project. | |
14 | */ | |
65e81670 | 15 | |
28f573a2 | 16 | #include <string.h> |
48fe4d62 BM |
17 | #include <openssl/err.h> |
18 | ||
9b398ef2 | 19 | #include "internal/cryptlib.h" |
5784a521 | 20 | #include "internal/bn_int.h" |
65e81670 | 21 | #include "ec_lcl.h" |
48fe4d62 | 22 | |
37c660ff | 23 | /* |
0d4fb843 | 24 | * This file implements the wNAF-based interleaving multi-exponentiation method |
dea0eb2c RS |
25 | * Formerly at: |
26 | * http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp | |
27 | * You might now find it here: | |
28 | * http://link.springer.com/chapter/10.1007%2F3-540-45537-X_13 | |
29 | * http://www.bmoeller.de/pdf/TI-01-08.multiexp.pdf | |
30 | * For multiplication with precomputation, we use wNAF splitting, formerly at: | |
31 | * http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp | |
37c660ff | 32 | */ |
48fe4d62 | 33 | |
37c660ff | 34 | /* structure for precomputed multiples of the generator */ |
3aef36ff | 35 | struct ec_pre_comp_st { |
0f113f3e MC |
36 | const EC_GROUP *group; /* parent EC_GROUP object */ |
37 | size_t blocksize; /* block size for wNAF splitting */ | |
38 | size_t numblocks; /* max. number of blocks for which we have | |
39 | * precomputation */ | |
40 | size_t w; /* window size */ | |
41 | EC_POINT **points; /* array with pre-calculated multiples of | |
42 | * generator: 'num' pointers to EC_POINT | |
43 | * objects followed by a NULL */ | |
44 | size_t num; /* numblocks * 2^(w-1) */ | |
2f545ae4 | 45 | CRYPTO_REF_COUNT references; |
9b398ef2 | 46 | CRYPTO_RWLOCK *lock; |
3aef36ff | 47 | }; |
37c660ff BM |
48 | |
49 | static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group) | |
0f113f3e MC |
50 | { |
51 | EC_PRE_COMP *ret = NULL; | |
52 | ||
53 | if (!group) | |
54 | return NULL; | |
55 | ||
64b25758 | 56 | ret = OPENSSL_zalloc(sizeof(*ret)); |
90945fa3 | 57 | if (ret == NULL) { |
0f113f3e MC |
58 | ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE); |
59 | return ret; | |
60 | } | |
9b398ef2 | 61 | |
0f113f3e MC |
62 | ret->group = group; |
63 | ret->blocksize = 8; /* default */ | |
0f113f3e | 64 | ret->w = 4; /* default */ |
0f113f3e | 65 | ret->references = 1; |
9b398ef2 AG |
66 | |
67 | ret->lock = CRYPTO_THREAD_lock_new(); | |
68 | if (ret->lock == NULL) { | |
69 | ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE); | |
70 | OPENSSL_free(ret); | |
71 | return NULL; | |
72 | } | |
0f113f3e MC |
73 | return ret; |
74 | } | |
37c660ff | 75 | |
3aef36ff | 76 | EC_PRE_COMP *EC_ec_pre_comp_dup(EC_PRE_COMP *pre) |
0f113f3e | 77 | { |
9b398ef2 | 78 | int i; |
3aef36ff | 79 | if (pre != NULL) |
2f545ae4 | 80 | CRYPTO_UP_REF(&pre->references, &i, pre->lock); |
3aef36ff | 81 | return pre; |
0f113f3e | 82 | } |
37c660ff | 83 | |
3aef36ff | 84 | void EC_ec_pre_comp_free(EC_PRE_COMP *pre) |
0f113f3e | 85 | { |
9b398ef2 AG |
86 | int i; |
87 | ||
88 | if (pre == NULL) | |
89 | return; | |
90 | ||
2f545ae4 | 91 | CRYPTO_DOWN_REF(&pre->references, &i, pre->lock); |
9b398ef2 AG |
92 | REF_PRINT_COUNT("EC_ec", pre); |
93 | if (i > 0) | |
0f113f3e | 94 | return; |
9b398ef2 | 95 | REF_ASSERT_ISNT(i < 0); |
ba729265 | 96 | |
3aef36ff RS |
97 | if (pre->points != NULL) { |
98 | EC_POINT **pts; | |
37c660ff | 99 | |
3aef36ff RS |
100 | for (pts = pre->points; *pts != NULL; pts++) |
101 | EC_POINT_free(*pts); | |
0f113f3e MC |
102 | OPENSSL_free(pre->points); |
103 | } | |
9b398ef2 | 104 | CRYPTO_THREAD_lock_free(pre->lock); |
0f113f3e MC |
105 | OPENSSL_free(pre); |
106 | } | |
37c660ff | 107 | |
0f113f3e MC |
108 | /* |
109 | * TODO: table should be optimised for the wNAF-based implementation, | |
110 | * sometimes smaller windows will give better performance (thus the | |
111 | * boundaries should be increased) | |
c05940ed | 112 | */ |
3ba1f111 | 113 | #define EC_window_bits_for_scalar_size(b) \ |
0f113f3e MC |
114 | ((size_t) \ |
115 | ((b) >= 2000 ? 6 : \ | |
116 | (b) >= 800 ? 5 : \ | |
117 | (b) >= 300 ? 4 : \ | |
118 | (b) >= 70 ? 3 : \ | |
119 | (b) >= 20 ? 2 : \ | |
120 | 1)) | |
3ba1f111 | 121 | |
c80fd6b2 MC |
122 | /*- |
123 | * Compute | |
3ba1f111 BM |
124 | * \sum scalars[i]*points[i], |
125 | * also including | |
126 | * scalar*generator | |
127 | * in the addition if scalar != NULL | |
128 | */ | |
7793f30e | 129 | int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, |
0f113f3e MC |
130 | size_t num, const EC_POINT *points[], const BIGNUM *scalars[], |
131 | BN_CTX *ctx) | |
132 | { | |
133 | BN_CTX *new_ctx = NULL; | |
134 | const EC_POINT *generator = NULL; | |
135 | EC_POINT *tmp = NULL; | |
136 | size_t totalnum; | |
137 | size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */ | |
138 | size_t pre_points_per_block = 0; | |
139 | size_t i, j; | |
140 | int k; | |
141 | int r_is_inverted = 0; | |
142 | int r_is_at_infinity = 1; | |
143 | size_t *wsize = NULL; /* individual window sizes */ | |
144 | signed char **wNAF = NULL; /* individual wNAFs */ | |
145 | size_t *wNAF_len = NULL; | |
146 | size_t max_len = 0; | |
147 | size_t num_val; | |
148 | EC_POINT **val = NULL; /* precomputation */ | |
149 | EC_POINT **v; | |
150 | EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or | |
151 | * 'pre_comp->points' */ | |
152 | const EC_PRE_COMP *pre_comp = NULL; | |
153 | int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be | |
154 | * treated like other scalars, i.e. | |
155 | * precomputation is not available */ | |
156 | int ret = 0; | |
157 | ||
158 | if (group->meth != r->meth) { | |
159 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
160 | return 0; | |
161 | } | |
162 | ||
163 | if ((scalar == NULL) && (num == 0)) { | |
164 | return EC_POINT_set_to_infinity(group, r); | |
165 | } | |
166 | ||
167 | for (i = 0; i < num; i++) { | |
168 | if (group->meth != points[i]->meth) { | |
169 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
170 | return 0; | |
171 | } | |
172 | } | |
173 | ||
174 | if (ctx == NULL) { | |
175 | ctx = new_ctx = BN_CTX_new(); | |
176 | if (ctx == NULL) | |
177 | goto err; | |
178 | } | |
179 | ||
180 | if (scalar != NULL) { | |
181 | generator = EC_GROUP_get0_generator(group); | |
182 | if (generator == NULL) { | |
183 | ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR); | |
184 | goto err; | |
185 | } | |
186 | ||
187 | /* look if we can use precomputed multiples of generator */ | |
188 | ||
3aef36ff | 189 | pre_comp = group->pre_comp.ec; |
0f113f3e MC |
190 | if (pre_comp && pre_comp->numblocks |
191 | && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == | |
192 | 0)) { | |
193 | blocksize = pre_comp->blocksize; | |
194 | ||
195 | /* | |
196 | * determine maximum number of blocks that wNAF splitting may | |
197 | * yield (NB: maximum wNAF length is bit length plus one) | |
198 | */ | |
199 | numblocks = (BN_num_bits(scalar) / blocksize) + 1; | |
200 | ||
201 | /* | |
202 | * we cannot use more blocks than we have precomputation for | |
203 | */ | |
204 | if (numblocks > pre_comp->numblocks) | |
205 | numblocks = pre_comp->numblocks; | |
206 | ||
207 | pre_points_per_block = (size_t)1 << (pre_comp->w - 1); | |
208 | ||
209 | /* check that pre_comp looks sane */ | |
210 | if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block)) { | |
211 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
212 | goto err; | |
213 | } | |
214 | } else { | |
215 | /* can't use precomputation */ | |
216 | pre_comp = NULL; | |
217 | numblocks = 1; | |
218 | num_scalar = 1; /* treat 'scalar' like 'num'-th element of | |
219 | * 'scalars' */ | |
220 | } | |
221 | } | |
222 | ||
223 | totalnum = num + numblocks; | |
224 | ||
225 | wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]); | |
226 | wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]); | |
227 | wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space | |
228 | * for pivot */ | |
229 | val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]); | |
230 | ||
231 | /* Ensure wNAF is initialised in case we end up going to err */ | |
90945fa3 | 232 | if (wNAF != NULL) |
0f113f3e MC |
233 | wNAF[0] = NULL; /* preliminary pivot */ |
234 | ||
90945fa3 | 235 | if (wsize == NULL || wNAF_len == NULL || wNAF == NULL || val_sub == NULL) { |
0f113f3e MC |
236 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); |
237 | goto err; | |
238 | } | |
239 | ||
240 | /* | |
241 | * num_val will be the total number of temporarily precomputed points | |
242 | */ | |
243 | num_val = 0; | |
244 | ||
245 | for (i = 0; i < num + num_scalar; i++) { | |
246 | size_t bits; | |
247 | ||
248 | bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar); | |
249 | wsize[i] = EC_window_bits_for_scalar_size(bits); | |
250 | num_val += (size_t)1 << (wsize[i] - 1); | |
251 | wNAF[i + 1] = NULL; /* make sure we always have a pivot */ | |
252 | wNAF[i] = | |
253 | bn_compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], | |
254 | &wNAF_len[i]); | |
255 | if (wNAF[i] == NULL) | |
256 | goto err; | |
257 | if (wNAF_len[i] > max_len) | |
258 | max_len = wNAF_len[i]; | |
259 | } | |
260 | ||
261 | if (numblocks) { | |
262 | /* we go here iff scalar != NULL */ | |
263 | ||
264 | if (pre_comp == NULL) { | |
265 | if (num_scalar != 1) { | |
266 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
267 | goto err; | |
268 | } | |
269 | /* we have already generated a wNAF for 'scalar' */ | |
270 | } else { | |
271 | signed char *tmp_wNAF = NULL; | |
272 | size_t tmp_len = 0; | |
273 | ||
274 | if (num_scalar != 0) { | |
275 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
276 | goto err; | |
277 | } | |
278 | ||
279 | /* | |
280 | * use the window size for which we have precomputation | |
281 | */ | |
282 | wsize[num] = pre_comp->w; | |
283 | tmp_wNAF = bn_compute_wNAF(scalar, wsize[num], &tmp_len); | |
284 | if (!tmp_wNAF) | |
285 | goto err; | |
286 | ||
287 | if (tmp_len <= max_len) { | |
288 | /* | |
289 | * One of the other wNAFs is at least as long as the wNAF | |
290 | * belonging to the generator, so wNAF splitting will not buy | |
291 | * us anything. | |
292 | */ | |
293 | ||
294 | numblocks = 1; | |
295 | totalnum = num + 1; /* don't use wNAF splitting */ | |
296 | wNAF[num] = tmp_wNAF; | |
297 | wNAF[num + 1] = NULL; | |
298 | wNAF_len[num] = tmp_len; | |
0f113f3e MC |
299 | /* |
300 | * pre_comp->points starts with the points that we need here: | |
301 | */ | |
302 | val_sub[num] = pre_comp->points; | |
303 | } else { | |
304 | /* | |
305 | * don't include tmp_wNAF directly into wNAF array - use wNAF | |
306 | * splitting and include the blocks | |
307 | */ | |
308 | ||
309 | signed char *pp; | |
310 | EC_POINT **tmp_points; | |
311 | ||
312 | if (tmp_len < numblocks * blocksize) { | |
313 | /* | |
314 | * possibly we can do with fewer blocks than estimated | |
315 | */ | |
316 | numblocks = (tmp_len + blocksize - 1) / blocksize; | |
317 | if (numblocks > pre_comp->numblocks) { | |
318 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
0e9eb1a5 | 319 | OPENSSL_free(tmp_wNAF); |
0f113f3e MC |
320 | goto err; |
321 | } | |
322 | totalnum = num + numblocks; | |
323 | } | |
324 | ||
325 | /* split wNAF in 'numblocks' parts */ | |
326 | pp = tmp_wNAF; | |
327 | tmp_points = pre_comp->points; | |
328 | ||
329 | for (i = num; i < totalnum; i++) { | |
330 | if (i < totalnum - 1) { | |
331 | wNAF_len[i] = blocksize; | |
332 | if (tmp_len < blocksize) { | |
333 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
0e9eb1a5 | 334 | OPENSSL_free(tmp_wNAF); |
0f113f3e MC |
335 | goto err; |
336 | } | |
337 | tmp_len -= blocksize; | |
338 | } else | |
339 | /* | |
340 | * last block gets whatever is left (this could be | |
341 | * more or less than 'blocksize'!) | |
342 | */ | |
343 | wNAF_len[i] = tmp_len; | |
344 | ||
345 | wNAF[i + 1] = NULL; | |
346 | wNAF[i] = OPENSSL_malloc(wNAF_len[i]); | |
347 | if (wNAF[i] == NULL) { | |
348 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
349 | OPENSSL_free(tmp_wNAF); | |
350 | goto err; | |
351 | } | |
352 | memcpy(wNAF[i], pp, wNAF_len[i]); | |
353 | if (wNAF_len[i] > max_len) | |
354 | max_len = wNAF_len[i]; | |
355 | ||
356 | if (*tmp_points == NULL) { | |
357 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
358 | OPENSSL_free(tmp_wNAF); | |
359 | goto err; | |
360 | } | |
361 | val_sub[i] = tmp_points; | |
362 | tmp_points += pre_points_per_block; | |
363 | pp += blocksize; | |
364 | } | |
365 | OPENSSL_free(tmp_wNAF); | |
366 | } | |
367 | } | |
368 | } | |
369 | ||
370 | /* | |
371 | * All points we precompute now go into a single array 'val'. | |
372 | * 'val_sub[i]' is a pointer to the subarray for the i-th point, or to a | |
373 | * subarray of 'pre_comp->points' if we already have precomputation. | |
374 | */ | |
375 | val = OPENSSL_malloc((num_val + 1) * sizeof val[0]); | |
376 | if (val == NULL) { | |
377 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
378 | goto err; | |
379 | } | |
380 | val[num_val] = NULL; /* pivot element */ | |
381 | ||
382 | /* allocate points for precomputation */ | |
383 | v = val; | |
384 | for (i = 0; i < num + num_scalar; i++) { | |
385 | val_sub[i] = v; | |
386 | for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
387 | *v = EC_POINT_new(group); | |
388 | if (*v == NULL) | |
389 | goto err; | |
390 | v++; | |
391 | } | |
392 | } | |
393 | if (!(v == val + num_val)) { | |
394 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
395 | goto err; | |
396 | } | |
397 | ||
75ebbd9a | 398 | if ((tmp = EC_POINT_new(group)) == NULL) |
0f113f3e MC |
399 | goto err; |
400 | ||
50e735f9 MC |
401 | /*- |
402 | * prepare precomputed values: | |
403 | * val_sub[i][0] := points[i] | |
404 | * val_sub[i][1] := 3 * points[i] | |
405 | * val_sub[i][2] := 5 * points[i] | |
406 | * ... | |
407 | */ | |
0f113f3e MC |
408 | for (i = 0; i < num + num_scalar; i++) { |
409 | if (i < num) { | |
410 | if (!EC_POINT_copy(val_sub[i][0], points[i])) | |
411 | goto err; | |
412 | } else { | |
413 | if (!EC_POINT_copy(val_sub[i][0], generator)) | |
414 | goto err; | |
415 | } | |
416 | ||
417 | if (wsize[i] > 1) { | |
418 | if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) | |
419 | goto err; | |
420 | for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
421 | if (!EC_POINT_add | |
422 | (group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) | |
423 | goto err; | |
424 | } | |
425 | } | |
426 | } | |
427 | ||
0f113f3e MC |
428 | if (!EC_POINTs_make_affine(group, num_val, val, ctx)) |
429 | goto err; | |
3ba1f111 | 430 | |
0f113f3e MC |
431 | r_is_at_infinity = 1; |
432 | ||
433 | for (k = max_len - 1; k >= 0; k--) { | |
434 | if (!r_is_at_infinity) { | |
435 | if (!EC_POINT_dbl(group, r, r, ctx)) | |
436 | goto err; | |
437 | } | |
438 | ||
439 | for (i = 0; i < totalnum; i++) { | |
440 | if (wNAF_len[i] > (size_t)k) { | |
441 | int digit = wNAF[i][k]; | |
442 | int is_neg; | |
443 | ||
444 | if (digit) { | |
445 | is_neg = digit < 0; | |
446 | ||
447 | if (is_neg) | |
448 | digit = -digit; | |
449 | ||
450 | if (is_neg != r_is_inverted) { | |
451 | if (!r_is_at_infinity) { | |
452 | if (!EC_POINT_invert(group, r, ctx)) | |
453 | goto err; | |
454 | } | |
455 | r_is_inverted = !r_is_inverted; | |
456 | } | |
457 | ||
458 | /* digit > 0 */ | |
459 | ||
460 | if (r_is_at_infinity) { | |
461 | if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) | |
462 | goto err; | |
463 | r_is_at_infinity = 0; | |
464 | } else { | |
465 | if (!EC_POINT_add | |
466 | (group, r, r, val_sub[i][digit >> 1], ctx)) | |
467 | goto err; | |
468 | } | |
469 | } | |
470 | } | |
471 | } | |
472 | } | |
473 | ||
474 | if (r_is_at_infinity) { | |
475 | if (!EC_POINT_set_to_infinity(group, r)) | |
476 | goto err; | |
477 | } else { | |
478 | if (r_is_inverted) | |
479 | if (!EC_POINT_invert(group, r, ctx)) | |
480 | goto err; | |
481 | } | |
482 | ||
483 | ret = 1; | |
3ba1f111 BM |
484 | |
485 | err: | |
23a1d5e9 | 486 | BN_CTX_free(new_ctx); |
8fdc3734 | 487 | EC_POINT_free(tmp); |
b548a1f1 RS |
488 | OPENSSL_free(wsize); |
489 | OPENSSL_free(wNAF_len); | |
0f113f3e MC |
490 | if (wNAF != NULL) { |
491 | signed char **w; | |
492 | ||
493 | for (w = wNAF; *w != NULL; w++) | |
494 | OPENSSL_free(*w); | |
495 | ||
496 | OPENSSL_free(wNAF); | |
497 | } | |
498 | if (val != NULL) { | |
499 | for (v = val; *v != NULL; v++) | |
500 | EC_POINT_clear_free(*v); | |
501 | ||
502 | OPENSSL_free(val); | |
503 | } | |
b548a1f1 | 504 | OPENSSL_free(val_sub); |
0f113f3e MC |
505 | return ret; |
506 | } | |
38374911 | 507 | |
1d97c843 TH |
508 | /*- |
509 | * ec_wNAF_precompute_mult() | |
37c660ff BM |
510 | * creates an EC_PRE_COMP object with preprecomputed multiples of the generator |
511 | * for use with wNAF splitting as implemented in ec_wNAF_mul(). | |
0f113f3e | 512 | * |
37c660ff BM |
513 | * 'pre_comp->points' is an array of multiples of the generator |
514 | * of the following form: | |
515 | * points[0] = generator; | |
516 | * points[1] = 3 * generator; | |
517 | * ... | |
518 | * points[2^(w-1)-1] = (2^(w-1)-1) * generator; | |
519 | * points[2^(w-1)] = 2^blocksize * generator; | |
520 | * points[2^(w-1)+1] = 3 * 2^blocksize * generator; | |
521 | * ... | |
522 | * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator | |
523 | * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator | |
524 | * ... | |
525 | * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator | |
526 | * points[2^(w-1)*numblocks] = NULL | |
7793f30e | 527 | */ |
7793f30e | 528 | int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx) |
0f113f3e MC |
529 | { |
530 | const EC_POINT *generator; | |
531 | EC_POINT *tmp_point = NULL, *base = NULL, **var; | |
532 | BN_CTX *new_ctx = NULL; | |
be2e334f | 533 | const BIGNUM *order; |
0f113f3e MC |
534 | size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num; |
535 | EC_POINT **points = NULL; | |
536 | EC_PRE_COMP *pre_comp; | |
537 | int ret = 0; | |
538 | ||
539 | /* if there is an old EC_PRE_COMP object, throw it away */ | |
2c52ac9b | 540 | EC_pre_comp_free(group); |
0f113f3e MC |
541 | if ((pre_comp = ec_pre_comp_new(group)) == NULL) |
542 | return 0; | |
543 | ||
544 | generator = EC_GROUP_get0_generator(group); | |
545 | if (generator == NULL) { | |
546 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); | |
547 | goto err; | |
548 | } | |
549 | ||
550 | if (ctx == NULL) { | |
551 | ctx = new_ctx = BN_CTX_new(); | |
552 | if (ctx == NULL) | |
553 | goto err; | |
554 | } | |
555 | ||
556 | BN_CTX_start(ctx); | |
0f113f3e | 557 | |
be2e334f DSH |
558 | order = EC_GROUP_get0_order(group); |
559 | if (order == NULL) | |
0f113f3e MC |
560 | goto err; |
561 | if (BN_is_zero(order)) { | |
562 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); | |
563 | goto err; | |
564 | } | |
565 | ||
566 | bits = BN_num_bits(order); | |
567 | /* | |
568 | * The following parameters mean we precompute (approximately) one point | |
569 | * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other | |
570 | * bit lengths, other parameter combinations might provide better | |
571 | * efficiency. | |
572 | */ | |
573 | blocksize = 8; | |
574 | w = 4; | |
575 | if (EC_window_bits_for_scalar_size(bits) > w) { | |
576 | /* let's not make the window too small ... */ | |
577 | w = EC_window_bits_for_scalar_size(bits); | |
578 | } | |
579 | ||
580 | numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks | |
581 | * to use for wNAF | |
582 | * splitting */ | |
583 | ||
584 | pre_points_per_block = (size_t)1 << (w - 1); | |
585 | num = pre_points_per_block * numblocks; /* number of points to compute | |
586 | * and store */ | |
587 | ||
b4faea50 | 588 | points = OPENSSL_malloc(sizeof(*points) * (num + 1)); |
90945fa3 | 589 | if (points == NULL) { |
0f113f3e MC |
590 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
591 | goto err; | |
592 | } | |
593 | ||
594 | var = points; | |
595 | var[num] = NULL; /* pivot */ | |
596 | for (i = 0; i < num; i++) { | |
597 | if ((var[i] = EC_POINT_new(group)) == NULL) { | |
598 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
599 | goto err; | |
600 | } | |
601 | } | |
602 | ||
75ebbd9a RS |
603 | if ((tmp_point = EC_POINT_new(group)) == NULL |
604 | || (base = EC_POINT_new(group)) == NULL) { | |
0f113f3e MC |
605 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
606 | goto err; | |
607 | } | |
608 | ||
609 | if (!EC_POINT_copy(base, generator)) | |
610 | goto err; | |
611 | ||
612 | /* do the precomputation */ | |
613 | for (i = 0; i < numblocks; i++) { | |
614 | size_t j; | |
615 | ||
616 | if (!EC_POINT_dbl(group, tmp_point, base, ctx)) | |
617 | goto err; | |
618 | ||
619 | if (!EC_POINT_copy(*var++, base)) | |
620 | goto err; | |
621 | ||
622 | for (j = 1; j < pre_points_per_block; j++, var++) { | |
623 | /* | |
624 | * calculate odd multiples of the current base point | |
625 | */ | |
626 | if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx)) | |
627 | goto err; | |
628 | } | |
629 | ||
630 | if (i < numblocks - 1) { | |
631 | /* | |
632 | * get the next base (multiply current one by 2^blocksize) | |
633 | */ | |
634 | size_t k; | |
635 | ||
636 | if (blocksize <= 2) { | |
637 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR); | |
638 | goto err; | |
639 | } | |
640 | ||
641 | if (!EC_POINT_dbl(group, base, tmp_point, ctx)) | |
642 | goto err; | |
643 | for (k = 2; k < blocksize; k++) { | |
644 | if (!EC_POINT_dbl(group, base, base, ctx)) | |
645 | goto err; | |
646 | } | |
647 | } | |
648 | } | |
649 | ||
650 | if (!EC_POINTs_make_affine(group, num, points, ctx)) | |
651 | goto err; | |
652 | ||
653 | pre_comp->group = group; | |
654 | pre_comp->blocksize = blocksize; | |
655 | pre_comp->numblocks = numblocks; | |
656 | pre_comp->w = w; | |
657 | pre_comp->points = points; | |
658 | points = NULL; | |
659 | pre_comp->num = num; | |
3aef36ff | 660 | SETPRECOMP(group, ec, pre_comp); |
0f113f3e | 661 | pre_comp = NULL; |
0f113f3e | 662 | ret = 1; |
3aef36ff | 663 | |
38374911 | 664 | err: |
0f113f3e MC |
665 | if (ctx != NULL) |
666 | BN_CTX_end(ctx); | |
23a1d5e9 | 667 | BN_CTX_free(new_ctx); |
3aef36ff | 668 | EC_ec_pre_comp_free(pre_comp); |
0f113f3e MC |
669 | if (points) { |
670 | EC_POINT **p; | |
671 | ||
672 | for (p = points; *p != NULL; p++) | |
673 | EC_POINT_free(*p); | |
674 | OPENSSL_free(points); | |
675 | } | |
8fdc3734 RS |
676 | EC_POINT_free(tmp_point); |
677 | EC_POINT_free(base); | |
0f113f3e MC |
678 | return ret; |
679 | } | |
7793f30e | 680 | |
37c660ff | 681 | int ec_wNAF_have_precompute_mult(const EC_GROUP *group) |
0f113f3e | 682 | { |
3aef36ff | 683 | return HAVEPRECOMP(group, ec); |
0f113f3e | 684 | } |