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Commit | Line | Data |
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65e81670 | 1 | /* crypto/ec/ec_mult.c */ |
35b73a1f | 2 | /* |
37c660ff | 3 | * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project. |
35b73a1f | 4 | */ |
65e81670 | 5 | /* ==================================================================== |
19f6c524 | 6 | * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved. |
65e81670 BM |
7 | * |
8 | * Redistribution and use in source and binary forms, with or without | |
9 | * modification, are permitted provided that the following conditions | |
10 | * are met: | |
11 | * | |
12 | * 1. Redistributions of source code must retain the above copyright | |
0f113f3e | 13 | * notice, this list of conditions and the following disclaimer. |
65e81670 BM |
14 | * |
15 | * 2. Redistributions in binary form must reproduce the above copyright | |
16 | * notice, this list of conditions and the following disclaimer in | |
17 | * the documentation and/or other materials provided with the | |
18 | * distribution. | |
19 | * | |
20 | * 3. All advertising materials mentioning features or use of this | |
21 | * software must display the following acknowledgment: | |
22 | * "This product includes software developed by the OpenSSL Project | |
23 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
24 | * | |
25 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
26 | * endorse or promote products derived from this software without | |
27 | * prior written permission. For written permission, please contact | |
28 | * openssl-core@openssl.org. | |
29 | * | |
30 | * 5. Products derived from this software may not be called "OpenSSL" | |
31 | * nor may "OpenSSL" appear in their names without prior written | |
32 | * permission of the OpenSSL Project. | |
33 | * | |
34 | * 6. Redistributions of any form whatsoever must retain the following | |
35 | * acknowledgment: | |
36 | * "This product includes software developed by the OpenSSL Project | |
37 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
38 | * | |
39 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
40 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
41 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
42 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
43 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
44 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
45 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
46 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
47 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
48 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
49 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
50 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
51 | * ==================================================================== | |
52 | * | |
53 | * This product includes cryptographic software written by Eric Young | |
54 | * (eay@cryptsoft.com). This product includes software written by Tim | |
55 | * Hudson (tjh@cryptsoft.com). | |
56 | * | |
57 | */ | |
7793f30e BM |
58 | /* ==================================================================== |
59 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. | |
60 | * Portions of this software developed by SUN MICROSYSTEMS, INC., | |
61 | * and contributed to the OpenSSL project. | |
62 | */ | |
65e81670 | 63 | |
28f573a2 | 64 | #include <string.h> |
48fe4d62 BM |
65 | #include <openssl/err.h> |
66 | ||
5784a521 | 67 | #include "internal/bn_int.h" |
65e81670 | 68 | #include "ec_lcl.h" |
48fe4d62 | 69 | |
37c660ff BM |
70 | /* |
71 | * This file implements the wNAF-based interleaving multi-exponentation method | |
72 | * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>); | |
73 | * for multiplication with precomputation, we use wNAF splitting | |
74 | * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp>). | |
75 | */ | |
48fe4d62 | 76 | |
37c660ff | 77 | /* structure for precomputed multiples of the generator */ |
3aef36ff | 78 | struct ec_pre_comp_st { |
0f113f3e MC |
79 | const EC_GROUP *group; /* parent EC_GROUP object */ |
80 | size_t blocksize; /* block size for wNAF splitting */ | |
81 | size_t numblocks; /* max. number of blocks for which we have | |
82 | * precomputation */ | |
83 | size_t w; /* window size */ | |
84 | EC_POINT **points; /* array with pre-calculated multiples of | |
85 | * generator: 'num' pointers to EC_POINT | |
86 | * objects followed by a NULL */ | |
87 | size_t num; /* numblocks * 2^(w-1) */ | |
88 | int references; | |
3aef36ff | 89 | }; |
37c660ff BM |
90 | |
91 | static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group) | |
0f113f3e MC |
92 | { |
93 | EC_PRE_COMP *ret = NULL; | |
94 | ||
95 | if (!group) | |
96 | return NULL; | |
97 | ||
64b25758 | 98 | ret = OPENSSL_zalloc(sizeof(*ret)); |
90945fa3 | 99 | if (ret == NULL) { |
0f113f3e MC |
100 | ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE); |
101 | return ret; | |
102 | } | |
103 | ret->group = group; | |
104 | ret->blocksize = 8; /* default */ | |
0f113f3e | 105 | ret->w = 4; /* default */ |
0f113f3e MC |
106 | ret->references = 1; |
107 | return ret; | |
108 | } | |
37c660ff | 109 | |
3aef36ff | 110 | EC_PRE_COMP *EC_ec_pre_comp_dup(EC_PRE_COMP *pre) |
0f113f3e | 111 | { |
3aef36ff RS |
112 | if (pre != NULL) |
113 | CRYPTO_add(&pre->references, 1, CRYPTO_LOCK_EC_PRE_COMP); | |
114 | return pre; | |
0f113f3e | 115 | } |
37c660ff | 116 | |
3aef36ff | 117 | void EC_ec_pre_comp_free(EC_PRE_COMP *pre) |
0f113f3e | 118 | { |
3aef36ff RS |
119 | if (pre == NULL |
120 | || CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP) > 0) | |
0f113f3e | 121 | return; |
ba729265 | 122 | |
3aef36ff RS |
123 | if (pre->points != NULL) { |
124 | EC_POINT **pts; | |
37c660ff | 125 | |
3aef36ff RS |
126 | for (pts = pre->points; *pts != NULL; pts++) |
127 | EC_POINT_free(*pts); | |
0f113f3e MC |
128 | OPENSSL_free(pre->points); |
129 | } | |
130 | OPENSSL_free(pre); | |
131 | } | |
37c660ff | 132 | |
0f113f3e MC |
133 | /* |
134 | * TODO: table should be optimised for the wNAF-based implementation, | |
135 | * sometimes smaller windows will give better performance (thus the | |
136 | * boundaries should be increased) | |
c05940ed | 137 | */ |
3ba1f111 | 138 | #define EC_window_bits_for_scalar_size(b) \ |
0f113f3e MC |
139 | ((size_t) \ |
140 | ((b) >= 2000 ? 6 : \ | |
141 | (b) >= 800 ? 5 : \ | |
142 | (b) >= 300 ? 4 : \ | |
143 | (b) >= 70 ? 3 : \ | |
144 | (b) >= 20 ? 2 : \ | |
145 | 1)) | |
3ba1f111 | 146 | |
c80fd6b2 MC |
147 | /*- |
148 | * Compute | |
3ba1f111 BM |
149 | * \sum scalars[i]*points[i], |
150 | * also including | |
151 | * scalar*generator | |
152 | * in the addition if scalar != NULL | |
153 | */ | |
7793f30e | 154 | int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, |
0f113f3e MC |
155 | size_t num, const EC_POINT *points[], const BIGNUM *scalars[], |
156 | BN_CTX *ctx) | |
157 | { | |
158 | BN_CTX *new_ctx = NULL; | |
159 | const EC_POINT *generator = NULL; | |
160 | EC_POINT *tmp = NULL; | |
161 | size_t totalnum; | |
162 | size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */ | |
163 | size_t pre_points_per_block = 0; | |
164 | size_t i, j; | |
165 | int k; | |
166 | int r_is_inverted = 0; | |
167 | int r_is_at_infinity = 1; | |
168 | size_t *wsize = NULL; /* individual window sizes */ | |
169 | signed char **wNAF = NULL; /* individual wNAFs */ | |
170 | size_t *wNAF_len = NULL; | |
171 | size_t max_len = 0; | |
172 | size_t num_val; | |
173 | EC_POINT **val = NULL; /* precomputation */ | |
174 | EC_POINT **v; | |
175 | EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or | |
176 | * 'pre_comp->points' */ | |
177 | const EC_PRE_COMP *pre_comp = NULL; | |
178 | int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be | |
179 | * treated like other scalars, i.e. | |
180 | * precomputation is not available */ | |
181 | int ret = 0; | |
182 | ||
183 | if (group->meth != r->meth) { | |
184 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
185 | return 0; | |
186 | } | |
187 | ||
188 | if ((scalar == NULL) && (num == 0)) { | |
189 | return EC_POINT_set_to_infinity(group, r); | |
190 | } | |
191 | ||
192 | for (i = 0; i < num; i++) { | |
193 | if (group->meth != points[i]->meth) { | |
194 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
195 | return 0; | |
196 | } | |
197 | } | |
198 | ||
199 | if (ctx == NULL) { | |
200 | ctx = new_ctx = BN_CTX_new(); | |
201 | if (ctx == NULL) | |
202 | goto err; | |
203 | } | |
204 | ||
205 | if (scalar != NULL) { | |
206 | generator = EC_GROUP_get0_generator(group); | |
207 | if (generator == NULL) { | |
208 | ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR); | |
209 | goto err; | |
210 | } | |
211 | ||
212 | /* look if we can use precomputed multiples of generator */ | |
213 | ||
3aef36ff | 214 | pre_comp = group->pre_comp.ec; |
0f113f3e MC |
215 | if (pre_comp && pre_comp->numblocks |
216 | && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == | |
217 | 0)) { | |
218 | blocksize = pre_comp->blocksize; | |
219 | ||
220 | /* | |
221 | * determine maximum number of blocks that wNAF splitting may | |
222 | * yield (NB: maximum wNAF length is bit length plus one) | |
223 | */ | |
224 | numblocks = (BN_num_bits(scalar) / blocksize) + 1; | |
225 | ||
226 | /* | |
227 | * we cannot use more blocks than we have precomputation for | |
228 | */ | |
229 | if (numblocks > pre_comp->numblocks) | |
230 | numblocks = pre_comp->numblocks; | |
231 | ||
232 | pre_points_per_block = (size_t)1 << (pre_comp->w - 1); | |
233 | ||
234 | /* check that pre_comp looks sane */ | |
235 | if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block)) { | |
236 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
237 | goto err; | |
238 | } | |
239 | } else { | |
240 | /* can't use precomputation */ | |
241 | pre_comp = NULL; | |
242 | numblocks = 1; | |
243 | num_scalar = 1; /* treat 'scalar' like 'num'-th element of | |
244 | * 'scalars' */ | |
245 | } | |
246 | } | |
247 | ||
248 | totalnum = num + numblocks; | |
249 | ||
250 | wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]); | |
251 | wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]); | |
252 | wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space | |
253 | * for pivot */ | |
254 | val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]); | |
255 | ||
256 | /* Ensure wNAF is initialised in case we end up going to err */ | |
90945fa3 | 257 | if (wNAF != NULL) |
0f113f3e MC |
258 | wNAF[0] = NULL; /* preliminary pivot */ |
259 | ||
90945fa3 | 260 | if (wsize == NULL || wNAF_len == NULL || wNAF == NULL || val_sub == NULL) { |
0f113f3e MC |
261 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); |
262 | goto err; | |
263 | } | |
264 | ||
265 | /* | |
266 | * num_val will be the total number of temporarily precomputed points | |
267 | */ | |
268 | num_val = 0; | |
269 | ||
270 | for (i = 0; i < num + num_scalar; i++) { | |
271 | size_t bits; | |
272 | ||
273 | bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar); | |
274 | wsize[i] = EC_window_bits_for_scalar_size(bits); | |
275 | num_val += (size_t)1 << (wsize[i] - 1); | |
276 | wNAF[i + 1] = NULL; /* make sure we always have a pivot */ | |
277 | wNAF[i] = | |
278 | bn_compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], | |
279 | &wNAF_len[i]); | |
280 | if (wNAF[i] == NULL) | |
281 | goto err; | |
282 | if (wNAF_len[i] > max_len) | |
283 | max_len = wNAF_len[i]; | |
284 | } | |
285 | ||
286 | if (numblocks) { | |
287 | /* we go here iff scalar != NULL */ | |
288 | ||
289 | if (pre_comp == NULL) { | |
290 | if (num_scalar != 1) { | |
291 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
292 | goto err; | |
293 | } | |
294 | /* we have already generated a wNAF for 'scalar' */ | |
295 | } else { | |
296 | signed char *tmp_wNAF = NULL; | |
297 | size_t tmp_len = 0; | |
298 | ||
299 | if (num_scalar != 0) { | |
300 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
301 | goto err; | |
302 | } | |
303 | ||
304 | /* | |
305 | * use the window size for which we have precomputation | |
306 | */ | |
307 | wsize[num] = pre_comp->w; | |
308 | tmp_wNAF = bn_compute_wNAF(scalar, wsize[num], &tmp_len); | |
309 | if (!tmp_wNAF) | |
310 | goto err; | |
311 | ||
312 | if (tmp_len <= max_len) { | |
313 | /* | |
314 | * One of the other wNAFs is at least as long as the wNAF | |
315 | * belonging to the generator, so wNAF splitting will not buy | |
316 | * us anything. | |
317 | */ | |
318 | ||
319 | numblocks = 1; | |
320 | totalnum = num + 1; /* don't use wNAF splitting */ | |
321 | wNAF[num] = tmp_wNAF; | |
322 | wNAF[num + 1] = NULL; | |
323 | wNAF_len[num] = tmp_len; | |
324 | if (tmp_len > max_len) | |
325 | max_len = tmp_len; | |
326 | /* | |
327 | * pre_comp->points starts with the points that we need here: | |
328 | */ | |
329 | val_sub[num] = pre_comp->points; | |
330 | } else { | |
331 | /* | |
332 | * don't include tmp_wNAF directly into wNAF array - use wNAF | |
333 | * splitting and include the blocks | |
334 | */ | |
335 | ||
336 | signed char *pp; | |
337 | EC_POINT **tmp_points; | |
338 | ||
339 | if (tmp_len < numblocks * blocksize) { | |
340 | /* | |
341 | * possibly we can do with fewer blocks than estimated | |
342 | */ | |
343 | numblocks = (tmp_len + blocksize - 1) / blocksize; | |
344 | if (numblocks > pre_comp->numblocks) { | |
345 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
346 | goto err; | |
347 | } | |
348 | totalnum = num + numblocks; | |
349 | } | |
350 | ||
351 | /* split wNAF in 'numblocks' parts */ | |
352 | pp = tmp_wNAF; | |
353 | tmp_points = pre_comp->points; | |
354 | ||
355 | for (i = num; i < totalnum; i++) { | |
356 | if (i < totalnum - 1) { | |
357 | wNAF_len[i] = blocksize; | |
358 | if (tmp_len < blocksize) { | |
359 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
360 | goto err; | |
361 | } | |
362 | tmp_len -= blocksize; | |
363 | } else | |
364 | /* | |
365 | * last block gets whatever is left (this could be | |
366 | * more or less than 'blocksize'!) | |
367 | */ | |
368 | wNAF_len[i] = tmp_len; | |
369 | ||
370 | wNAF[i + 1] = NULL; | |
371 | wNAF[i] = OPENSSL_malloc(wNAF_len[i]); | |
372 | if (wNAF[i] == NULL) { | |
373 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
374 | OPENSSL_free(tmp_wNAF); | |
375 | goto err; | |
376 | } | |
377 | memcpy(wNAF[i], pp, wNAF_len[i]); | |
378 | if (wNAF_len[i] > max_len) | |
379 | max_len = wNAF_len[i]; | |
380 | ||
381 | if (*tmp_points == NULL) { | |
382 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
383 | OPENSSL_free(tmp_wNAF); | |
384 | goto err; | |
385 | } | |
386 | val_sub[i] = tmp_points; | |
387 | tmp_points += pre_points_per_block; | |
388 | pp += blocksize; | |
389 | } | |
390 | OPENSSL_free(tmp_wNAF); | |
391 | } | |
392 | } | |
393 | } | |
394 | ||
395 | /* | |
396 | * All points we precompute now go into a single array 'val'. | |
397 | * 'val_sub[i]' is a pointer to the subarray for the i-th point, or to a | |
398 | * subarray of 'pre_comp->points' if we already have precomputation. | |
399 | */ | |
400 | val = OPENSSL_malloc((num_val + 1) * sizeof val[0]); | |
401 | if (val == NULL) { | |
402 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
403 | goto err; | |
404 | } | |
405 | val[num_val] = NULL; /* pivot element */ | |
406 | ||
407 | /* allocate points for precomputation */ | |
408 | v = val; | |
409 | for (i = 0; i < num + num_scalar; i++) { | |
410 | val_sub[i] = v; | |
411 | for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
412 | *v = EC_POINT_new(group); | |
413 | if (*v == NULL) | |
414 | goto err; | |
415 | v++; | |
416 | } | |
417 | } | |
418 | if (!(v == val + num_val)) { | |
419 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
420 | goto err; | |
421 | } | |
422 | ||
75ebbd9a | 423 | if ((tmp = EC_POINT_new(group)) == NULL) |
0f113f3e MC |
424 | goto err; |
425 | ||
50e735f9 MC |
426 | /*- |
427 | * prepare precomputed values: | |
428 | * val_sub[i][0] := points[i] | |
429 | * val_sub[i][1] := 3 * points[i] | |
430 | * val_sub[i][2] := 5 * points[i] | |
431 | * ... | |
432 | */ | |
0f113f3e MC |
433 | for (i = 0; i < num + num_scalar; i++) { |
434 | if (i < num) { | |
435 | if (!EC_POINT_copy(val_sub[i][0], points[i])) | |
436 | goto err; | |
437 | } else { | |
438 | if (!EC_POINT_copy(val_sub[i][0], generator)) | |
439 | goto err; | |
440 | } | |
441 | ||
442 | if (wsize[i] > 1) { | |
443 | if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) | |
444 | goto err; | |
445 | for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
446 | if (!EC_POINT_add | |
447 | (group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) | |
448 | goto err; | |
449 | } | |
450 | } | |
451 | } | |
452 | ||
0f113f3e MC |
453 | if (!EC_POINTs_make_affine(group, num_val, val, ctx)) |
454 | goto err; | |
3ba1f111 | 455 | |
0f113f3e MC |
456 | r_is_at_infinity = 1; |
457 | ||
458 | for (k = max_len - 1; k >= 0; k--) { | |
459 | if (!r_is_at_infinity) { | |
460 | if (!EC_POINT_dbl(group, r, r, ctx)) | |
461 | goto err; | |
462 | } | |
463 | ||
464 | for (i = 0; i < totalnum; i++) { | |
465 | if (wNAF_len[i] > (size_t)k) { | |
466 | int digit = wNAF[i][k]; | |
467 | int is_neg; | |
468 | ||
469 | if (digit) { | |
470 | is_neg = digit < 0; | |
471 | ||
472 | if (is_neg) | |
473 | digit = -digit; | |
474 | ||
475 | if (is_neg != r_is_inverted) { | |
476 | if (!r_is_at_infinity) { | |
477 | if (!EC_POINT_invert(group, r, ctx)) | |
478 | goto err; | |
479 | } | |
480 | r_is_inverted = !r_is_inverted; | |
481 | } | |
482 | ||
483 | /* digit > 0 */ | |
484 | ||
485 | if (r_is_at_infinity) { | |
486 | if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) | |
487 | goto err; | |
488 | r_is_at_infinity = 0; | |
489 | } else { | |
490 | if (!EC_POINT_add | |
491 | (group, r, r, val_sub[i][digit >> 1], ctx)) | |
492 | goto err; | |
493 | } | |
494 | } | |
495 | } | |
496 | } | |
497 | } | |
498 | ||
499 | if (r_is_at_infinity) { | |
500 | if (!EC_POINT_set_to_infinity(group, r)) | |
501 | goto err; | |
502 | } else { | |
503 | if (r_is_inverted) | |
504 | if (!EC_POINT_invert(group, r, ctx)) | |
505 | goto err; | |
506 | } | |
507 | ||
508 | ret = 1; | |
3ba1f111 BM |
509 | |
510 | err: | |
23a1d5e9 | 511 | BN_CTX_free(new_ctx); |
8fdc3734 | 512 | EC_POINT_free(tmp); |
b548a1f1 RS |
513 | OPENSSL_free(wsize); |
514 | OPENSSL_free(wNAF_len); | |
0f113f3e MC |
515 | if (wNAF != NULL) { |
516 | signed char **w; | |
517 | ||
518 | for (w = wNAF; *w != NULL; w++) | |
519 | OPENSSL_free(*w); | |
520 | ||
521 | OPENSSL_free(wNAF); | |
522 | } | |
523 | if (val != NULL) { | |
524 | for (v = val; *v != NULL; v++) | |
525 | EC_POINT_clear_free(*v); | |
526 | ||
527 | OPENSSL_free(val); | |
528 | } | |
b548a1f1 | 529 | OPENSSL_free(val_sub); |
0f113f3e MC |
530 | return ret; |
531 | } | |
38374911 | 532 | |
1d97c843 TH |
533 | /*- |
534 | * ec_wNAF_precompute_mult() | |
37c660ff BM |
535 | * creates an EC_PRE_COMP object with preprecomputed multiples of the generator |
536 | * for use with wNAF splitting as implemented in ec_wNAF_mul(). | |
0f113f3e | 537 | * |
37c660ff BM |
538 | * 'pre_comp->points' is an array of multiples of the generator |
539 | * of the following form: | |
540 | * points[0] = generator; | |
541 | * points[1] = 3 * generator; | |
542 | * ... | |
543 | * points[2^(w-1)-1] = (2^(w-1)-1) * generator; | |
544 | * points[2^(w-1)] = 2^blocksize * generator; | |
545 | * points[2^(w-1)+1] = 3 * 2^blocksize * generator; | |
546 | * ... | |
547 | * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator | |
548 | * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator | |
549 | * ... | |
550 | * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator | |
551 | * points[2^(w-1)*numblocks] = NULL | |
7793f30e | 552 | */ |
7793f30e | 553 | int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx) |
0f113f3e MC |
554 | { |
555 | const EC_POINT *generator; | |
556 | EC_POINT *tmp_point = NULL, *base = NULL, **var; | |
557 | BN_CTX *new_ctx = NULL; | |
558 | BIGNUM *order; | |
559 | size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num; | |
560 | EC_POINT **points = NULL; | |
561 | EC_PRE_COMP *pre_comp; | |
562 | int ret = 0; | |
563 | ||
564 | /* if there is an old EC_PRE_COMP object, throw it away */ | |
2c52ac9b | 565 | EC_pre_comp_free(group); |
0f113f3e MC |
566 | if ((pre_comp = ec_pre_comp_new(group)) == NULL) |
567 | return 0; | |
568 | ||
569 | generator = EC_GROUP_get0_generator(group); | |
570 | if (generator == NULL) { | |
571 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); | |
572 | goto err; | |
573 | } | |
574 | ||
575 | if (ctx == NULL) { | |
576 | ctx = new_ctx = BN_CTX_new(); | |
577 | if (ctx == NULL) | |
578 | goto err; | |
579 | } | |
580 | ||
581 | BN_CTX_start(ctx); | |
582 | order = BN_CTX_get(ctx); | |
583 | if (order == NULL) | |
584 | goto err; | |
585 | ||
586 | if (!EC_GROUP_get_order(group, order, ctx)) | |
587 | goto err; | |
588 | if (BN_is_zero(order)) { | |
589 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); | |
590 | goto err; | |
591 | } | |
592 | ||
593 | bits = BN_num_bits(order); | |
594 | /* | |
595 | * The following parameters mean we precompute (approximately) one point | |
596 | * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other | |
597 | * bit lengths, other parameter combinations might provide better | |
598 | * efficiency. | |
599 | */ | |
600 | blocksize = 8; | |
601 | w = 4; | |
602 | if (EC_window_bits_for_scalar_size(bits) > w) { | |
603 | /* let's not make the window too small ... */ | |
604 | w = EC_window_bits_for_scalar_size(bits); | |
605 | } | |
606 | ||
607 | numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks | |
608 | * to use for wNAF | |
609 | * splitting */ | |
610 | ||
611 | pre_points_per_block = (size_t)1 << (w - 1); | |
612 | num = pre_points_per_block * numblocks; /* number of points to compute | |
613 | * and store */ | |
614 | ||
b4faea50 | 615 | points = OPENSSL_malloc(sizeof(*points) * (num + 1)); |
90945fa3 | 616 | if (points == NULL) { |
0f113f3e MC |
617 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
618 | goto err; | |
619 | } | |
620 | ||
621 | var = points; | |
622 | var[num] = NULL; /* pivot */ | |
623 | for (i = 0; i < num; i++) { | |
624 | if ((var[i] = EC_POINT_new(group)) == NULL) { | |
625 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
626 | goto err; | |
627 | } | |
628 | } | |
629 | ||
75ebbd9a RS |
630 | if ((tmp_point = EC_POINT_new(group)) == NULL |
631 | || (base = EC_POINT_new(group)) == NULL) { | |
0f113f3e MC |
632 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
633 | goto err; | |
634 | } | |
635 | ||
636 | if (!EC_POINT_copy(base, generator)) | |
637 | goto err; | |
638 | ||
639 | /* do the precomputation */ | |
640 | for (i = 0; i < numblocks; i++) { | |
641 | size_t j; | |
642 | ||
643 | if (!EC_POINT_dbl(group, tmp_point, base, ctx)) | |
644 | goto err; | |
645 | ||
646 | if (!EC_POINT_copy(*var++, base)) | |
647 | goto err; | |
648 | ||
649 | for (j = 1; j < pre_points_per_block; j++, var++) { | |
650 | /* | |
651 | * calculate odd multiples of the current base point | |
652 | */ | |
653 | if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx)) | |
654 | goto err; | |
655 | } | |
656 | ||
657 | if (i < numblocks - 1) { | |
658 | /* | |
659 | * get the next base (multiply current one by 2^blocksize) | |
660 | */ | |
661 | size_t k; | |
662 | ||
663 | if (blocksize <= 2) { | |
664 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR); | |
665 | goto err; | |
666 | } | |
667 | ||
668 | if (!EC_POINT_dbl(group, base, tmp_point, ctx)) | |
669 | goto err; | |
670 | for (k = 2; k < blocksize; k++) { | |
671 | if (!EC_POINT_dbl(group, base, base, ctx)) | |
672 | goto err; | |
673 | } | |
674 | } | |
675 | } | |
676 | ||
677 | if (!EC_POINTs_make_affine(group, num, points, ctx)) | |
678 | goto err; | |
679 | ||
680 | pre_comp->group = group; | |
681 | pre_comp->blocksize = blocksize; | |
682 | pre_comp->numblocks = numblocks; | |
683 | pre_comp->w = w; | |
684 | pre_comp->points = points; | |
685 | points = NULL; | |
686 | pre_comp->num = num; | |
3aef36ff | 687 | SETPRECOMP(group, ec, pre_comp); |
0f113f3e | 688 | pre_comp = NULL; |
0f113f3e | 689 | ret = 1; |
3aef36ff | 690 | |
38374911 | 691 | err: |
0f113f3e MC |
692 | if (ctx != NULL) |
693 | BN_CTX_end(ctx); | |
23a1d5e9 | 694 | BN_CTX_free(new_ctx); |
3aef36ff | 695 | EC_ec_pre_comp_free(pre_comp); |
0f113f3e MC |
696 | if (points) { |
697 | EC_POINT **p; | |
698 | ||
699 | for (p = points; *p != NULL; p++) | |
700 | EC_POINT_free(*p); | |
701 | OPENSSL_free(points); | |
702 | } | |
8fdc3734 RS |
703 | EC_POINT_free(tmp_point); |
704 | EC_POINT_free(base); | |
0f113f3e MC |
705 | return ret; |
706 | } | |
7793f30e | 707 | |
37c660ff | 708 | int ec_wNAF_have_precompute_mult(const EC_GROUP *group) |
0f113f3e | 709 | { |
3aef36ff | 710 | return HAVEPRECOMP(group, ec); |
0f113f3e | 711 | } |