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Commit | Line | Data |
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35b73a1f | 1 | /* |
37c660ff | 2 | * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project. |
35b73a1f | 3 | */ |
65e81670 | 4 | /* ==================================================================== |
19f6c524 | 5 | * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved. |
65e81670 BM |
6 | * |
7 | * Redistribution and use in source and binary forms, with or without | |
8 | * modification, are permitted provided that the following conditions | |
9 | * are met: | |
10 | * | |
11 | * 1. Redistributions of source code must retain the above copyright | |
0f113f3e | 12 | * notice, this list of conditions and the following disclaimer. |
65e81670 BM |
13 | * |
14 | * 2. Redistributions in binary form must reproduce the above copyright | |
15 | * notice, this list of conditions and the following disclaimer in | |
16 | * the documentation and/or other materials provided with the | |
17 | * distribution. | |
18 | * | |
19 | * 3. All advertising materials mentioning features or use of this | |
20 | * software must display the following acknowledgment: | |
21 | * "This product includes software developed by the OpenSSL Project | |
22 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
23 | * | |
24 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
25 | * endorse or promote products derived from this software without | |
26 | * prior written permission. For written permission, please contact | |
27 | * openssl-core@openssl.org. | |
28 | * | |
29 | * 5. Products derived from this software may not be called "OpenSSL" | |
30 | * nor may "OpenSSL" appear in their names without prior written | |
31 | * permission of the OpenSSL Project. | |
32 | * | |
33 | * 6. Redistributions of any form whatsoever must retain the following | |
34 | * acknowledgment: | |
35 | * "This product includes software developed by the OpenSSL Project | |
36 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
37 | * | |
38 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
39 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
40 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
41 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
42 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
43 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
44 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
45 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
46 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
47 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
48 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
49 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
50 | * ==================================================================== | |
51 | * | |
52 | * This product includes cryptographic software written by Eric Young | |
53 | * (eay@cryptsoft.com). This product includes software written by Tim | |
54 | * Hudson (tjh@cryptsoft.com). | |
55 | * | |
56 | */ | |
7793f30e BM |
57 | /* ==================================================================== |
58 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. | |
59 | * Portions of this software developed by SUN MICROSYSTEMS, INC., | |
60 | * and contributed to the OpenSSL project. | |
61 | */ | |
65e81670 | 62 | |
28f573a2 | 63 | #include <string.h> |
48fe4d62 BM |
64 | #include <openssl/err.h> |
65 | ||
5784a521 | 66 | #include "internal/bn_int.h" |
65e81670 | 67 | #include "ec_lcl.h" |
48fe4d62 | 68 | |
37c660ff | 69 | /* |
0d4fb843 | 70 | * This file implements the wNAF-based interleaving multi-exponentiation method |
37c660ff BM |
71 | * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>); |
72 | * for multiplication with precomputation, we use wNAF splitting | |
73 | * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp>). | |
74 | */ | |
48fe4d62 | 75 | |
37c660ff | 76 | /* structure for precomputed multiples of the generator */ |
3aef36ff | 77 | struct ec_pre_comp_st { |
0f113f3e MC |
78 | const EC_GROUP *group; /* parent EC_GROUP object */ |
79 | size_t blocksize; /* block size for wNAF splitting */ | |
80 | size_t numblocks; /* max. number of blocks for which we have | |
81 | * precomputation */ | |
82 | size_t w; /* window size */ | |
83 | EC_POINT **points; /* array with pre-calculated multiples of | |
84 | * generator: 'num' pointers to EC_POINT | |
85 | * objects followed by a NULL */ | |
86 | size_t num; /* numblocks * 2^(w-1) */ | |
87 | int references; | |
3aef36ff | 88 | }; |
37c660ff BM |
89 | |
90 | static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group) | |
0f113f3e MC |
91 | { |
92 | EC_PRE_COMP *ret = NULL; | |
93 | ||
94 | if (!group) | |
95 | return NULL; | |
96 | ||
64b25758 | 97 | ret = OPENSSL_zalloc(sizeof(*ret)); |
90945fa3 | 98 | if (ret == NULL) { |
0f113f3e MC |
99 | ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE); |
100 | return ret; | |
101 | } | |
102 | ret->group = group; | |
103 | ret->blocksize = 8; /* default */ | |
0f113f3e | 104 | ret->w = 4; /* default */ |
0f113f3e MC |
105 | ret->references = 1; |
106 | return ret; | |
107 | } | |
37c660ff | 108 | |
3aef36ff | 109 | EC_PRE_COMP *EC_ec_pre_comp_dup(EC_PRE_COMP *pre) |
0f113f3e | 110 | { |
3aef36ff RS |
111 | if (pre != NULL) |
112 | CRYPTO_add(&pre->references, 1, CRYPTO_LOCK_EC_PRE_COMP); | |
113 | return pre; | |
0f113f3e | 114 | } |
37c660ff | 115 | |
3aef36ff | 116 | void EC_ec_pre_comp_free(EC_PRE_COMP *pre) |
0f113f3e | 117 | { |
3aef36ff RS |
118 | if (pre == NULL |
119 | || CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP) > 0) | |
0f113f3e | 120 | return; |
ba729265 | 121 | |
3aef36ff RS |
122 | if (pre->points != NULL) { |
123 | EC_POINT **pts; | |
37c660ff | 124 | |
3aef36ff RS |
125 | for (pts = pre->points; *pts != NULL; pts++) |
126 | EC_POINT_free(*pts); | |
0f113f3e MC |
127 | OPENSSL_free(pre->points); |
128 | } | |
129 | OPENSSL_free(pre); | |
130 | } | |
37c660ff | 131 | |
0f113f3e MC |
132 | /* |
133 | * TODO: table should be optimised for the wNAF-based implementation, | |
134 | * sometimes smaller windows will give better performance (thus the | |
135 | * boundaries should be increased) | |
c05940ed | 136 | */ |
3ba1f111 | 137 | #define EC_window_bits_for_scalar_size(b) \ |
0f113f3e MC |
138 | ((size_t) \ |
139 | ((b) >= 2000 ? 6 : \ | |
140 | (b) >= 800 ? 5 : \ | |
141 | (b) >= 300 ? 4 : \ | |
142 | (b) >= 70 ? 3 : \ | |
143 | (b) >= 20 ? 2 : \ | |
144 | 1)) | |
3ba1f111 | 145 | |
c80fd6b2 MC |
146 | /*- |
147 | * Compute | |
3ba1f111 BM |
148 | * \sum scalars[i]*points[i], |
149 | * also including | |
150 | * scalar*generator | |
151 | * in the addition if scalar != NULL | |
152 | */ | |
7793f30e | 153 | int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, |
0f113f3e MC |
154 | size_t num, const EC_POINT *points[], const BIGNUM *scalars[], |
155 | BN_CTX *ctx) | |
156 | { | |
157 | BN_CTX *new_ctx = NULL; | |
158 | const EC_POINT *generator = NULL; | |
159 | EC_POINT *tmp = NULL; | |
160 | size_t totalnum; | |
161 | size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */ | |
162 | size_t pre_points_per_block = 0; | |
163 | size_t i, j; | |
164 | int k; | |
165 | int r_is_inverted = 0; | |
166 | int r_is_at_infinity = 1; | |
167 | size_t *wsize = NULL; /* individual window sizes */ | |
168 | signed char **wNAF = NULL; /* individual wNAFs */ | |
169 | size_t *wNAF_len = NULL; | |
170 | size_t max_len = 0; | |
171 | size_t num_val; | |
172 | EC_POINT **val = NULL; /* precomputation */ | |
173 | EC_POINT **v; | |
174 | EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or | |
175 | * 'pre_comp->points' */ | |
176 | const EC_PRE_COMP *pre_comp = NULL; | |
177 | int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be | |
178 | * treated like other scalars, i.e. | |
179 | * precomputation is not available */ | |
180 | int ret = 0; | |
181 | ||
182 | if (group->meth != r->meth) { | |
183 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
184 | return 0; | |
185 | } | |
186 | ||
187 | if ((scalar == NULL) && (num == 0)) { | |
188 | return EC_POINT_set_to_infinity(group, r); | |
189 | } | |
190 | ||
191 | for (i = 0; i < num; i++) { | |
192 | if (group->meth != points[i]->meth) { | |
193 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
194 | return 0; | |
195 | } | |
196 | } | |
197 | ||
198 | if (ctx == NULL) { | |
199 | ctx = new_ctx = BN_CTX_new(); | |
200 | if (ctx == NULL) | |
201 | goto err; | |
202 | } | |
203 | ||
204 | if (scalar != NULL) { | |
205 | generator = EC_GROUP_get0_generator(group); | |
206 | if (generator == NULL) { | |
207 | ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR); | |
208 | goto err; | |
209 | } | |
210 | ||
211 | /* look if we can use precomputed multiples of generator */ | |
212 | ||
3aef36ff | 213 | pre_comp = group->pre_comp.ec; |
0f113f3e MC |
214 | if (pre_comp && pre_comp->numblocks |
215 | && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == | |
216 | 0)) { | |
217 | blocksize = pre_comp->blocksize; | |
218 | ||
219 | /* | |
220 | * determine maximum number of blocks that wNAF splitting may | |
221 | * yield (NB: maximum wNAF length is bit length plus one) | |
222 | */ | |
223 | numblocks = (BN_num_bits(scalar) / blocksize) + 1; | |
224 | ||
225 | /* | |
226 | * we cannot use more blocks than we have precomputation for | |
227 | */ | |
228 | if (numblocks > pre_comp->numblocks) | |
229 | numblocks = pre_comp->numblocks; | |
230 | ||
231 | pre_points_per_block = (size_t)1 << (pre_comp->w - 1); | |
232 | ||
233 | /* check that pre_comp looks sane */ | |
234 | if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block)) { | |
235 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
236 | goto err; | |
237 | } | |
238 | } else { | |
239 | /* can't use precomputation */ | |
240 | pre_comp = NULL; | |
241 | numblocks = 1; | |
242 | num_scalar = 1; /* treat 'scalar' like 'num'-th element of | |
243 | * 'scalars' */ | |
244 | } | |
245 | } | |
246 | ||
247 | totalnum = num + numblocks; | |
248 | ||
249 | wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]); | |
250 | wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]); | |
251 | wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space | |
252 | * for pivot */ | |
253 | val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]); | |
254 | ||
255 | /* Ensure wNAF is initialised in case we end up going to err */ | |
90945fa3 | 256 | if (wNAF != NULL) |
0f113f3e MC |
257 | wNAF[0] = NULL; /* preliminary pivot */ |
258 | ||
90945fa3 | 259 | if (wsize == NULL || wNAF_len == NULL || wNAF == NULL || val_sub == NULL) { |
0f113f3e MC |
260 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); |
261 | goto err; | |
262 | } | |
263 | ||
264 | /* | |
265 | * num_val will be the total number of temporarily precomputed points | |
266 | */ | |
267 | num_val = 0; | |
268 | ||
269 | for (i = 0; i < num + num_scalar; i++) { | |
270 | size_t bits; | |
271 | ||
272 | bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar); | |
273 | wsize[i] = EC_window_bits_for_scalar_size(bits); | |
274 | num_val += (size_t)1 << (wsize[i] - 1); | |
275 | wNAF[i + 1] = NULL; /* make sure we always have a pivot */ | |
276 | wNAF[i] = | |
277 | bn_compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], | |
278 | &wNAF_len[i]); | |
279 | if (wNAF[i] == NULL) | |
280 | goto err; | |
281 | if (wNAF_len[i] > max_len) | |
282 | max_len = wNAF_len[i]; | |
283 | } | |
284 | ||
285 | if (numblocks) { | |
286 | /* we go here iff scalar != NULL */ | |
287 | ||
288 | if (pre_comp == NULL) { | |
289 | if (num_scalar != 1) { | |
290 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
291 | goto err; | |
292 | } | |
293 | /* we have already generated a wNAF for 'scalar' */ | |
294 | } else { | |
295 | signed char *tmp_wNAF = NULL; | |
296 | size_t tmp_len = 0; | |
297 | ||
298 | if (num_scalar != 0) { | |
299 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
300 | goto err; | |
301 | } | |
302 | ||
303 | /* | |
304 | * use the window size for which we have precomputation | |
305 | */ | |
306 | wsize[num] = pre_comp->w; | |
307 | tmp_wNAF = bn_compute_wNAF(scalar, wsize[num], &tmp_len); | |
308 | if (!tmp_wNAF) | |
309 | goto err; | |
310 | ||
311 | if (tmp_len <= max_len) { | |
312 | /* | |
313 | * One of the other wNAFs is at least as long as the wNAF | |
314 | * belonging to the generator, so wNAF splitting will not buy | |
315 | * us anything. | |
316 | */ | |
317 | ||
318 | numblocks = 1; | |
319 | totalnum = num + 1; /* don't use wNAF splitting */ | |
320 | wNAF[num] = tmp_wNAF; | |
321 | wNAF[num + 1] = NULL; | |
322 | wNAF_len[num] = tmp_len; | |
0f113f3e MC |
323 | /* |
324 | * pre_comp->points starts with the points that we need here: | |
325 | */ | |
326 | val_sub[num] = pre_comp->points; | |
327 | } else { | |
328 | /* | |
329 | * don't include tmp_wNAF directly into wNAF array - use wNAF | |
330 | * splitting and include the blocks | |
331 | */ | |
332 | ||
333 | signed char *pp; | |
334 | EC_POINT **tmp_points; | |
335 | ||
336 | if (tmp_len < numblocks * blocksize) { | |
337 | /* | |
338 | * possibly we can do with fewer blocks than estimated | |
339 | */ | |
340 | numblocks = (tmp_len + blocksize - 1) / blocksize; | |
341 | if (numblocks > pre_comp->numblocks) { | |
342 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
343 | goto err; | |
344 | } | |
345 | totalnum = num + numblocks; | |
346 | } | |
347 | ||
348 | /* split wNAF in 'numblocks' parts */ | |
349 | pp = tmp_wNAF; | |
350 | tmp_points = pre_comp->points; | |
351 | ||
352 | for (i = num; i < totalnum; i++) { | |
353 | if (i < totalnum - 1) { | |
354 | wNAF_len[i] = blocksize; | |
355 | if (tmp_len < blocksize) { | |
356 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
357 | goto err; | |
358 | } | |
359 | tmp_len -= blocksize; | |
360 | } else | |
361 | /* | |
362 | * last block gets whatever is left (this could be | |
363 | * more or less than 'blocksize'!) | |
364 | */ | |
365 | wNAF_len[i] = tmp_len; | |
366 | ||
367 | wNAF[i + 1] = NULL; | |
368 | wNAF[i] = OPENSSL_malloc(wNAF_len[i]); | |
369 | if (wNAF[i] == NULL) { | |
370 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
371 | OPENSSL_free(tmp_wNAF); | |
372 | goto err; | |
373 | } | |
374 | memcpy(wNAF[i], pp, wNAF_len[i]); | |
375 | if (wNAF_len[i] > max_len) | |
376 | max_len = wNAF_len[i]; | |
377 | ||
378 | if (*tmp_points == NULL) { | |
379 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
380 | OPENSSL_free(tmp_wNAF); | |
381 | goto err; | |
382 | } | |
383 | val_sub[i] = tmp_points; | |
384 | tmp_points += pre_points_per_block; | |
385 | pp += blocksize; | |
386 | } | |
387 | OPENSSL_free(tmp_wNAF); | |
388 | } | |
389 | } | |
390 | } | |
391 | ||
392 | /* | |
393 | * All points we precompute now go into a single array 'val'. | |
394 | * 'val_sub[i]' is a pointer to the subarray for the i-th point, or to a | |
395 | * subarray of 'pre_comp->points' if we already have precomputation. | |
396 | */ | |
397 | val = OPENSSL_malloc((num_val + 1) * sizeof val[0]); | |
398 | if (val == NULL) { | |
399 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
400 | goto err; | |
401 | } | |
402 | val[num_val] = NULL; /* pivot element */ | |
403 | ||
404 | /* allocate points for precomputation */ | |
405 | v = val; | |
406 | for (i = 0; i < num + num_scalar; i++) { | |
407 | val_sub[i] = v; | |
408 | for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
409 | *v = EC_POINT_new(group); | |
410 | if (*v == NULL) | |
411 | goto err; | |
412 | v++; | |
413 | } | |
414 | } | |
415 | if (!(v == val + num_val)) { | |
416 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
417 | goto err; | |
418 | } | |
419 | ||
75ebbd9a | 420 | if ((tmp = EC_POINT_new(group)) == NULL) |
0f113f3e MC |
421 | goto err; |
422 | ||
50e735f9 MC |
423 | /*- |
424 | * prepare precomputed values: | |
425 | * val_sub[i][0] := points[i] | |
426 | * val_sub[i][1] := 3 * points[i] | |
427 | * val_sub[i][2] := 5 * points[i] | |
428 | * ... | |
429 | */ | |
0f113f3e MC |
430 | for (i = 0; i < num + num_scalar; i++) { |
431 | if (i < num) { | |
432 | if (!EC_POINT_copy(val_sub[i][0], points[i])) | |
433 | goto err; | |
434 | } else { | |
435 | if (!EC_POINT_copy(val_sub[i][0], generator)) | |
436 | goto err; | |
437 | } | |
438 | ||
439 | if (wsize[i] > 1) { | |
440 | if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) | |
441 | goto err; | |
442 | for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
443 | if (!EC_POINT_add | |
444 | (group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) | |
445 | goto err; | |
446 | } | |
447 | } | |
448 | } | |
449 | ||
0f113f3e MC |
450 | if (!EC_POINTs_make_affine(group, num_val, val, ctx)) |
451 | goto err; | |
3ba1f111 | 452 | |
0f113f3e MC |
453 | r_is_at_infinity = 1; |
454 | ||
455 | for (k = max_len - 1; k >= 0; k--) { | |
456 | if (!r_is_at_infinity) { | |
457 | if (!EC_POINT_dbl(group, r, r, ctx)) | |
458 | goto err; | |
459 | } | |
460 | ||
461 | for (i = 0; i < totalnum; i++) { | |
462 | if (wNAF_len[i] > (size_t)k) { | |
463 | int digit = wNAF[i][k]; | |
464 | int is_neg; | |
465 | ||
466 | if (digit) { | |
467 | is_neg = digit < 0; | |
468 | ||
469 | if (is_neg) | |
470 | digit = -digit; | |
471 | ||
472 | if (is_neg != r_is_inverted) { | |
473 | if (!r_is_at_infinity) { | |
474 | if (!EC_POINT_invert(group, r, ctx)) | |
475 | goto err; | |
476 | } | |
477 | r_is_inverted = !r_is_inverted; | |
478 | } | |
479 | ||
480 | /* digit > 0 */ | |
481 | ||
482 | if (r_is_at_infinity) { | |
483 | if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) | |
484 | goto err; | |
485 | r_is_at_infinity = 0; | |
486 | } else { | |
487 | if (!EC_POINT_add | |
488 | (group, r, r, val_sub[i][digit >> 1], ctx)) | |
489 | goto err; | |
490 | } | |
491 | } | |
492 | } | |
493 | } | |
494 | } | |
495 | ||
496 | if (r_is_at_infinity) { | |
497 | if (!EC_POINT_set_to_infinity(group, r)) | |
498 | goto err; | |
499 | } else { | |
500 | if (r_is_inverted) | |
501 | if (!EC_POINT_invert(group, r, ctx)) | |
502 | goto err; | |
503 | } | |
504 | ||
505 | ret = 1; | |
3ba1f111 BM |
506 | |
507 | err: | |
23a1d5e9 | 508 | BN_CTX_free(new_ctx); |
8fdc3734 | 509 | EC_POINT_free(tmp); |
b548a1f1 RS |
510 | OPENSSL_free(wsize); |
511 | OPENSSL_free(wNAF_len); | |
0f113f3e MC |
512 | if (wNAF != NULL) { |
513 | signed char **w; | |
514 | ||
515 | for (w = wNAF; *w != NULL; w++) | |
516 | OPENSSL_free(*w); | |
517 | ||
518 | OPENSSL_free(wNAF); | |
519 | } | |
520 | if (val != NULL) { | |
521 | for (v = val; *v != NULL; v++) | |
522 | EC_POINT_clear_free(*v); | |
523 | ||
524 | OPENSSL_free(val); | |
525 | } | |
b548a1f1 | 526 | OPENSSL_free(val_sub); |
0f113f3e MC |
527 | return ret; |
528 | } | |
38374911 | 529 | |
1d97c843 TH |
530 | /*- |
531 | * ec_wNAF_precompute_mult() | |
37c660ff BM |
532 | * creates an EC_PRE_COMP object with preprecomputed multiples of the generator |
533 | * for use with wNAF splitting as implemented in ec_wNAF_mul(). | |
0f113f3e | 534 | * |
37c660ff BM |
535 | * 'pre_comp->points' is an array of multiples of the generator |
536 | * of the following form: | |
537 | * points[0] = generator; | |
538 | * points[1] = 3 * generator; | |
539 | * ... | |
540 | * points[2^(w-1)-1] = (2^(w-1)-1) * generator; | |
541 | * points[2^(w-1)] = 2^blocksize * generator; | |
542 | * points[2^(w-1)+1] = 3 * 2^blocksize * generator; | |
543 | * ... | |
544 | * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator | |
545 | * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator | |
546 | * ... | |
547 | * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator | |
548 | * points[2^(w-1)*numblocks] = NULL | |
7793f30e | 549 | */ |
7793f30e | 550 | int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx) |
0f113f3e MC |
551 | { |
552 | const EC_POINT *generator; | |
553 | EC_POINT *tmp_point = NULL, *base = NULL, **var; | |
554 | BN_CTX *new_ctx = NULL; | |
be2e334f | 555 | const BIGNUM *order; |
0f113f3e MC |
556 | size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num; |
557 | EC_POINT **points = NULL; | |
558 | EC_PRE_COMP *pre_comp; | |
559 | int ret = 0; | |
560 | ||
561 | /* if there is an old EC_PRE_COMP object, throw it away */ | |
2c52ac9b | 562 | EC_pre_comp_free(group); |
0f113f3e MC |
563 | if ((pre_comp = ec_pre_comp_new(group)) == NULL) |
564 | return 0; | |
565 | ||
566 | generator = EC_GROUP_get0_generator(group); | |
567 | if (generator == NULL) { | |
568 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); | |
569 | goto err; | |
570 | } | |
571 | ||
572 | if (ctx == NULL) { | |
573 | ctx = new_ctx = BN_CTX_new(); | |
574 | if (ctx == NULL) | |
575 | goto err; | |
576 | } | |
577 | ||
578 | BN_CTX_start(ctx); | |
0f113f3e | 579 | |
be2e334f DSH |
580 | order = EC_GROUP_get0_order(group); |
581 | if (order == NULL) | |
0f113f3e MC |
582 | goto err; |
583 | if (BN_is_zero(order)) { | |
584 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); | |
585 | goto err; | |
586 | } | |
587 | ||
588 | bits = BN_num_bits(order); | |
589 | /* | |
590 | * The following parameters mean we precompute (approximately) one point | |
591 | * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other | |
592 | * bit lengths, other parameter combinations might provide better | |
593 | * efficiency. | |
594 | */ | |
595 | blocksize = 8; | |
596 | w = 4; | |
597 | if (EC_window_bits_for_scalar_size(bits) > w) { | |
598 | /* let's not make the window too small ... */ | |
599 | w = EC_window_bits_for_scalar_size(bits); | |
600 | } | |
601 | ||
602 | numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks | |
603 | * to use for wNAF | |
604 | * splitting */ | |
605 | ||
606 | pre_points_per_block = (size_t)1 << (w - 1); | |
607 | num = pre_points_per_block * numblocks; /* number of points to compute | |
608 | * and store */ | |
609 | ||
b4faea50 | 610 | points = OPENSSL_malloc(sizeof(*points) * (num + 1)); |
90945fa3 | 611 | if (points == NULL) { |
0f113f3e MC |
612 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
613 | goto err; | |
614 | } | |
615 | ||
616 | var = points; | |
617 | var[num] = NULL; /* pivot */ | |
618 | for (i = 0; i < num; i++) { | |
619 | if ((var[i] = EC_POINT_new(group)) == NULL) { | |
620 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
621 | goto err; | |
622 | } | |
623 | } | |
624 | ||
75ebbd9a RS |
625 | if ((tmp_point = EC_POINT_new(group)) == NULL |
626 | || (base = EC_POINT_new(group)) == NULL) { | |
0f113f3e MC |
627 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
628 | goto err; | |
629 | } | |
630 | ||
631 | if (!EC_POINT_copy(base, generator)) | |
632 | goto err; | |
633 | ||
634 | /* do the precomputation */ | |
635 | for (i = 0; i < numblocks; i++) { | |
636 | size_t j; | |
637 | ||
638 | if (!EC_POINT_dbl(group, tmp_point, base, ctx)) | |
639 | goto err; | |
640 | ||
641 | if (!EC_POINT_copy(*var++, base)) | |
642 | goto err; | |
643 | ||
644 | for (j = 1; j < pre_points_per_block; j++, var++) { | |
645 | /* | |
646 | * calculate odd multiples of the current base point | |
647 | */ | |
648 | if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx)) | |
649 | goto err; | |
650 | } | |
651 | ||
652 | if (i < numblocks - 1) { | |
653 | /* | |
654 | * get the next base (multiply current one by 2^blocksize) | |
655 | */ | |
656 | size_t k; | |
657 | ||
658 | if (blocksize <= 2) { | |
659 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR); | |
660 | goto err; | |
661 | } | |
662 | ||
663 | if (!EC_POINT_dbl(group, base, tmp_point, ctx)) | |
664 | goto err; | |
665 | for (k = 2; k < blocksize; k++) { | |
666 | if (!EC_POINT_dbl(group, base, base, ctx)) | |
667 | goto err; | |
668 | } | |
669 | } | |
670 | } | |
671 | ||
672 | if (!EC_POINTs_make_affine(group, num, points, ctx)) | |
673 | goto err; | |
674 | ||
675 | pre_comp->group = group; | |
676 | pre_comp->blocksize = blocksize; | |
677 | pre_comp->numblocks = numblocks; | |
678 | pre_comp->w = w; | |
679 | pre_comp->points = points; | |
680 | points = NULL; | |
681 | pre_comp->num = num; | |
3aef36ff | 682 | SETPRECOMP(group, ec, pre_comp); |
0f113f3e | 683 | pre_comp = NULL; |
0f113f3e | 684 | ret = 1; |
3aef36ff | 685 | |
38374911 | 686 | err: |
0f113f3e MC |
687 | if (ctx != NULL) |
688 | BN_CTX_end(ctx); | |
23a1d5e9 | 689 | BN_CTX_free(new_ctx); |
3aef36ff | 690 | EC_ec_pre_comp_free(pre_comp); |
0f113f3e MC |
691 | if (points) { |
692 | EC_POINT **p; | |
693 | ||
694 | for (p = points; *p != NULL; p++) | |
695 | EC_POINT_free(*p); | |
696 | OPENSSL_free(points); | |
697 | } | |
8fdc3734 RS |
698 | EC_POINT_free(tmp_point); |
699 | EC_POINT_free(base); | |
0f113f3e MC |
700 | return ret; |
701 | } | |
7793f30e | 702 | |
37c660ff | 703 | int ec_wNAF_have_precompute_mult(const EC_GROUP *group) |
0f113f3e | 704 | { |
3aef36ff | 705 | return HAVEPRECOMP(group, ec); |
0f113f3e | 706 | } |