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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 BM |
77 | /* structure for precomputed multiples of the generator */ |
78 | typedef 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; | |
37c660ff | 89 | } EC_PRE_COMP; |
0f113f3e | 90 | |
37c660ff BM |
91 | /* functions to manage EC_PRE_COMP within the EC_GROUP extra_data framework */ |
92 | static void *ec_pre_comp_dup(void *); | |
93 | static void ec_pre_comp_free(void *); | |
94 | static void ec_pre_comp_clear_free(void *); | |
95 | ||
96 | static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group) | |
0f113f3e MC |
97 | { |
98 | EC_PRE_COMP *ret = NULL; | |
99 | ||
100 | if (!group) | |
101 | return NULL; | |
102 | ||
64b25758 | 103 | ret = OPENSSL_zalloc(sizeof(*ret)); |
0f113f3e MC |
104 | if (!ret) { |
105 | ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE); | |
106 | return ret; | |
107 | } | |
108 | ret->group = group; | |
109 | ret->blocksize = 8; /* default */ | |
0f113f3e | 110 | ret->w = 4; /* default */ |
0f113f3e MC |
111 | ret->references = 1; |
112 | return ret; | |
113 | } | |
37c660ff BM |
114 | |
115 | static void *ec_pre_comp_dup(void *src_) | |
0f113f3e MC |
116 | { |
117 | EC_PRE_COMP *src = src_; | |
37c660ff | 118 | |
0f113f3e | 119 | /* no need to actually copy, these objects never change! */ |
37c660ff | 120 | |
0f113f3e | 121 | CRYPTO_add(&src->references, 1, CRYPTO_LOCK_EC_PRE_COMP); |
37c660ff | 122 | |
0f113f3e MC |
123 | return src_; |
124 | } | |
37c660ff BM |
125 | |
126 | static void ec_pre_comp_free(void *pre_) | |
0f113f3e MC |
127 | { |
128 | int i; | |
129 | EC_PRE_COMP *pre = pre_; | |
37c660ff | 130 | |
0f113f3e MC |
131 | if (!pre) |
132 | return; | |
ba729265 | 133 | |
0f113f3e MC |
134 | i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP); |
135 | if (i > 0) | |
136 | return; | |
ba729265 | 137 | |
0f113f3e MC |
138 | if (pre->points) { |
139 | EC_POINT **p; | |
37c660ff | 140 | |
0f113f3e MC |
141 | for (p = pre->points; *p != NULL; p++) |
142 | EC_POINT_free(*p); | |
143 | OPENSSL_free(pre->points); | |
144 | } | |
145 | OPENSSL_free(pre); | |
146 | } | |
37c660ff BM |
147 | |
148 | static void ec_pre_comp_clear_free(void *pre_) | |
0f113f3e MC |
149 | { |
150 | int i; | |
151 | EC_PRE_COMP *pre = pre_; | |
152 | ||
153 | if (!pre) | |
154 | return; | |
155 | ||
156 | i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP); | |
157 | if (i > 0) | |
158 | return; | |
159 | ||
160 | if (pre->points) { | |
161 | EC_POINT **p; | |
162 | ||
163 | for (p = pre->points; *p != NULL; p++) { | |
164 | EC_POINT_clear_free(*p); | |
b4faea50 | 165 | OPENSSL_cleanse(p, sizeof(*p)); |
0f113f3e MC |
166 | } |
167 | OPENSSL_free(pre->points); | |
168 | } | |
b4faea50 | 169 | OPENSSL_clear_free(pre, sizeof(*pre)); |
0f113f3e MC |
170 | } |
171 | ||
172 | /* | |
173 | * TODO: table should be optimised for the wNAF-based implementation, | |
174 | * sometimes smaller windows will give better performance (thus the | |
175 | * boundaries should be increased) | |
c05940ed | 176 | */ |
3ba1f111 | 177 | #define EC_window_bits_for_scalar_size(b) \ |
0f113f3e MC |
178 | ((size_t) \ |
179 | ((b) >= 2000 ? 6 : \ | |
180 | (b) >= 800 ? 5 : \ | |
181 | (b) >= 300 ? 4 : \ | |
182 | (b) >= 70 ? 3 : \ | |
183 | (b) >= 20 ? 2 : \ | |
184 | 1)) | |
3ba1f111 | 185 | |
c80fd6b2 MC |
186 | /*- |
187 | * Compute | |
3ba1f111 BM |
188 | * \sum scalars[i]*points[i], |
189 | * also including | |
190 | * scalar*generator | |
191 | * in the addition if scalar != NULL | |
192 | */ | |
7793f30e | 193 | int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, |
0f113f3e MC |
194 | size_t num, const EC_POINT *points[], const BIGNUM *scalars[], |
195 | BN_CTX *ctx) | |
196 | { | |
197 | BN_CTX *new_ctx = NULL; | |
198 | const EC_POINT *generator = NULL; | |
199 | EC_POINT *tmp = NULL; | |
200 | size_t totalnum; | |
201 | size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */ | |
202 | size_t pre_points_per_block = 0; | |
203 | size_t i, j; | |
204 | int k; | |
205 | int r_is_inverted = 0; | |
206 | int r_is_at_infinity = 1; | |
207 | size_t *wsize = NULL; /* individual window sizes */ | |
208 | signed char **wNAF = NULL; /* individual wNAFs */ | |
209 | size_t *wNAF_len = NULL; | |
210 | size_t max_len = 0; | |
211 | size_t num_val; | |
212 | EC_POINT **val = NULL; /* precomputation */ | |
213 | EC_POINT **v; | |
214 | EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or | |
215 | * 'pre_comp->points' */ | |
216 | const EC_PRE_COMP *pre_comp = NULL; | |
217 | int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be | |
218 | * treated like other scalars, i.e. | |
219 | * precomputation is not available */ | |
220 | int ret = 0; | |
221 | ||
222 | if (group->meth != r->meth) { | |
223 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
224 | return 0; | |
225 | } | |
226 | ||
227 | if ((scalar == NULL) && (num == 0)) { | |
228 | return EC_POINT_set_to_infinity(group, r); | |
229 | } | |
230 | ||
231 | for (i = 0; i < num; i++) { | |
232 | if (group->meth != points[i]->meth) { | |
233 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
234 | return 0; | |
235 | } | |
236 | } | |
237 | ||
238 | if (ctx == NULL) { | |
239 | ctx = new_ctx = BN_CTX_new(); | |
240 | if (ctx == NULL) | |
241 | goto err; | |
242 | } | |
243 | ||
244 | if (scalar != NULL) { | |
245 | generator = EC_GROUP_get0_generator(group); | |
246 | if (generator == NULL) { | |
247 | ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR); | |
248 | goto err; | |
249 | } | |
250 | ||
251 | /* look if we can use precomputed multiples of generator */ | |
252 | ||
253 | pre_comp = | |
254 | EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, | |
255 | ec_pre_comp_free, ec_pre_comp_clear_free); | |
256 | ||
257 | if (pre_comp && pre_comp->numblocks | |
258 | && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == | |
259 | 0)) { | |
260 | blocksize = pre_comp->blocksize; | |
261 | ||
262 | /* | |
263 | * determine maximum number of blocks that wNAF splitting may | |
264 | * yield (NB: maximum wNAF length is bit length plus one) | |
265 | */ | |
266 | numblocks = (BN_num_bits(scalar) / blocksize) + 1; | |
267 | ||
268 | /* | |
269 | * we cannot use more blocks than we have precomputation for | |
270 | */ | |
271 | if (numblocks > pre_comp->numblocks) | |
272 | numblocks = pre_comp->numblocks; | |
273 | ||
274 | pre_points_per_block = (size_t)1 << (pre_comp->w - 1); | |
275 | ||
276 | /* check that pre_comp looks sane */ | |
277 | if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block)) { | |
278 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
279 | goto err; | |
280 | } | |
281 | } else { | |
282 | /* can't use precomputation */ | |
283 | pre_comp = NULL; | |
284 | numblocks = 1; | |
285 | num_scalar = 1; /* treat 'scalar' like 'num'-th element of | |
286 | * 'scalars' */ | |
287 | } | |
288 | } | |
289 | ||
290 | totalnum = num + numblocks; | |
291 | ||
292 | wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]); | |
293 | wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]); | |
294 | wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space | |
295 | * for pivot */ | |
296 | val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]); | |
297 | ||
298 | /* Ensure wNAF is initialised in case we end up going to err */ | |
299 | if (wNAF) | |
300 | wNAF[0] = NULL; /* preliminary pivot */ | |
301 | ||
302 | if (!wsize || !wNAF_len || !wNAF || !val_sub) { | |
303 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
304 | goto err; | |
305 | } | |
306 | ||
307 | /* | |
308 | * num_val will be the total number of temporarily precomputed points | |
309 | */ | |
310 | num_val = 0; | |
311 | ||
312 | for (i = 0; i < num + num_scalar; i++) { | |
313 | size_t bits; | |
314 | ||
315 | bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar); | |
316 | wsize[i] = EC_window_bits_for_scalar_size(bits); | |
317 | num_val += (size_t)1 << (wsize[i] - 1); | |
318 | wNAF[i + 1] = NULL; /* make sure we always have a pivot */ | |
319 | wNAF[i] = | |
320 | bn_compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], | |
321 | &wNAF_len[i]); | |
322 | if (wNAF[i] == NULL) | |
323 | goto err; | |
324 | if (wNAF_len[i] > max_len) | |
325 | max_len = wNAF_len[i]; | |
326 | } | |
327 | ||
328 | if (numblocks) { | |
329 | /* we go here iff scalar != NULL */ | |
330 | ||
331 | if (pre_comp == NULL) { | |
332 | if (num_scalar != 1) { | |
333 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
334 | goto err; | |
335 | } | |
336 | /* we have already generated a wNAF for 'scalar' */ | |
337 | } else { | |
338 | signed char *tmp_wNAF = NULL; | |
339 | size_t tmp_len = 0; | |
340 | ||
341 | if (num_scalar != 0) { | |
342 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
343 | goto err; | |
344 | } | |
345 | ||
346 | /* | |
347 | * use the window size for which we have precomputation | |
348 | */ | |
349 | wsize[num] = pre_comp->w; | |
350 | tmp_wNAF = bn_compute_wNAF(scalar, wsize[num], &tmp_len); | |
351 | if (!tmp_wNAF) | |
352 | goto err; | |
353 | ||
354 | if (tmp_len <= max_len) { | |
355 | /* | |
356 | * One of the other wNAFs is at least as long as the wNAF | |
357 | * belonging to the generator, so wNAF splitting will not buy | |
358 | * us anything. | |
359 | */ | |
360 | ||
361 | numblocks = 1; | |
362 | totalnum = num + 1; /* don't use wNAF splitting */ | |
363 | wNAF[num] = tmp_wNAF; | |
364 | wNAF[num + 1] = NULL; | |
365 | wNAF_len[num] = tmp_len; | |
366 | if (tmp_len > max_len) | |
367 | max_len = tmp_len; | |
368 | /* | |
369 | * pre_comp->points starts with the points that we need here: | |
370 | */ | |
371 | val_sub[num] = pre_comp->points; | |
372 | } else { | |
373 | /* | |
374 | * don't include tmp_wNAF directly into wNAF array - use wNAF | |
375 | * splitting and include the blocks | |
376 | */ | |
377 | ||
378 | signed char *pp; | |
379 | EC_POINT **tmp_points; | |
380 | ||
381 | if (tmp_len < numblocks * blocksize) { | |
382 | /* | |
383 | * possibly we can do with fewer blocks than estimated | |
384 | */ | |
385 | numblocks = (tmp_len + blocksize - 1) / blocksize; | |
386 | if (numblocks > pre_comp->numblocks) { | |
387 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
388 | goto err; | |
389 | } | |
390 | totalnum = num + numblocks; | |
391 | } | |
392 | ||
393 | /* split wNAF in 'numblocks' parts */ | |
394 | pp = tmp_wNAF; | |
395 | tmp_points = pre_comp->points; | |
396 | ||
397 | for (i = num; i < totalnum; i++) { | |
398 | if (i < totalnum - 1) { | |
399 | wNAF_len[i] = blocksize; | |
400 | if (tmp_len < blocksize) { | |
401 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
402 | goto err; | |
403 | } | |
404 | tmp_len -= blocksize; | |
405 | } else | |
406 | /* | |
407 | * last block gets whatever is left (this could be | |
408 | * more or less than 'blocksize'!) | |
409 | */ | |
410 | wNAF_len[i] = tmp_len; | |
411 | ||
412 | wNAF[i + 1] = NULL; | |
413 | wNAF[i] = OPENSSL_malloc(wNAF_len[i]); | |
414 | if (wNAF[i] == NULL) { | |
415 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
416 | OPENSSL_free(tmp_wNAF); | |
417 | goto err; | |
418 | } | |
419 | memcpy(wNAF[i], pp, wNAF_len[i]); | |
420 | if (wNAF_len[i] > max_len) | |
421 | max_len = wNAF_len[i]; | |
422 | ||
423 | if (*tmp_points == NULL) { | |
424 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
425 | OPENSSL_free(tmp_wNAF); | |
426 | goto err; | |
427 | } | |
428 | val_sub[i] = tmp_points; | |
429 | tmp_points += pre_points_per_block; | |
430 | pp += blocksize; | |
431 | } | |
432 | OPENSSL_free(tmp_wNAF); | |
433 | } | |
434 | } | |
435 | } | |
436 | ||
437 | /* | |
438 | * All points we precompute now go into a single array 'val'. | |
439 | * 'val_sub[i]' is a pointer to the subarray for the i-th point, or to a | |
440 | * subarray of 'pre_comp->points' if we already have precomputation. | |
441 | */ | |
442 | val = OPENSSL_malloc((num_val + 1) * sizeof val[0]); | |
443 | if (val == NULL) { | |
444 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
445 | goto err; | |
446 | } | |
447 | val[num_val] = NULL; /* pivot element */ | |
448 | ||
449 | /* allocate points for precomputation */ | |
450 | v = val; | |
451 | for (i = 0; i < num + num_scalar; i++) { | |
452 | val_sub[i] = v; | |
453 | for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
454 | *v = EC_POINT_new(group); | |
455 | if (*v == NULL) | |
456 | goto err; | |
457 | v++; | |
458 | } | |
459 | } | |
460 | if (!(v == val + num_val)) { | |
461 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
462 | goto err; | |
463 | } | |
464 | ||
75ebbd9a | 465 | if ((tmp = EC_POINT_new(group)) == NULL) |
0f113f3e MC |
466 | goto err; |
467 | ||
50e735f9 MC |
468 | /*- |
469 | * prepare precomputed values: | |
470 | * val_sub[i][0] := points[i] | |
471 | * val_sub[i][1] := 3 * points[i] | |
472 | * val_sub[i][2] := 5 * points[i] | |
473 | * ... | |
474 | */ | |
0f113f3e MC |
475 | for (i = 0; i < num + num_scalar; i++) { |
476 | if (i < num) { | |
477 | if (!EC_POINT_copy(val_sub[i][0], points[i])) | |
478 | goto err; | |
479 | } else { | |
480 | if (!EC_POINT_copy(val_sub[i][0], generator)) | |
481 | goto err; | |
482 | } | |
483 | ||
484 | if (wsize[i] > 1) { | |
485 | if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) | |
486 | goto err; | |
487 | for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
488 | if (!EC_POINT_add | |
489 | (group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) | |
490 | goto err; | |
491 | } | |
492 | } | |
493 | } | |
494 | ||
0f113f3e MC |
495 | if (!EC_POINTs_make_affine(group, num_val, val, ctx)) |
496 | goto err; | |
3ba1f111 | 497 | |
0f113f3e MC |
498 | r_is_at_infinity = 1; |
499 | ||
500 | for (k = max_len - 1; k >= 0; k--) { | |
501 | if (!r_is_at_infinity) { | |
502 | if (!EC_POINT_dbl(group, r, r, ctx)) | |
503 | goto err; | |
504 | } | |
505 | ||
506 | for (i = 0; i < totalnum; i++) { | |
507 | if (wNAF_len[i] > (size_t)k) { | |
508 | int digit = wNAF[i][k]; | |
509 | int is_neg; | |
510 | ||
511 | if (digit) { | |
512 | is_neg = digit < 0; | |
513 | ||
514 | if (is_neg) | |
515 | digit = -digit; | |
516 | ||
517 | if (is_neg != r_is_inverted) { | |
518 | if (!r_is_at_infinity) { | |
519 | if (!EC_POINT_invert(group, r, ctx)) | |
520 | goto err; | |
521 | } | |
522 | r_is_inverted = !r_is_inverted; | |
523 | } | |
524 | ||
525 | /* digit > 0 */ | |
526 | ||
527 | if (r_is_at_infinity) { | |
528 | if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) | |
529 | goto err; | |
530 | r_is_at_infinity = 0; | |
531 | } else { | |
532 | if (!EC_POINT_add | |
533 | (group, r, r, val_sub[i][digit >> 1], ctx)) | |
534 | goto err; | |
535 | } | |
536 | } | |
537 | } | |
538 | } | |
539 | } | |
540 | ||
541 | if (r_is_at_infinity) { | |
542 | if (!EC_POINT_set_to_infinity(group, r)) | |
543 | goto err; | |
544 | } else { | |
545 | if (r_is_inverted) | |
546 | if (!EC_POINT_invert(group, r, ctx)) | |
547 | goto err; | |
548 | } | |
549 | ||
550 | ret = 1; | |
3ba1f111 BM |
551 | |
552 | err: | |
23a1d5e9 | 553 | BN_CTX_free(new_ctx); |
8fdc3734 | 554 | EC_POINT_free(tmp); |
b548a1f1 RS |
555 | OPENSSL_free(wsize); |
556 | OPENSSL_free(wNAF_len); | |
0f113f3e MC |
557 | if (wNAF != NULL) { |
558 | signed char **w; | |
559 | ||
560 | for (w = wNAF; *w != NULL; w++) | |
561 | OPENSSL_free(*w); | |
562 | ||
563 | OPENSSL_free(wNAF); | |
564 | } | |
565 | if (val != NULL) { | |
566 | for (v = val; *v != NULL; v++) | |
567 | EC_POINT_clear_free(*v); | |
568 | ||
569 | OPENSSL_free(val); | |
570 | } | |
b548a1f1 | 571 | OPENSSL_free(val_sub); |
0f113f3e MC |
572 | return ret; |
573 | } | |
38374911 | 574 | |
1d97c843 TH |
575 | /*- |
576 | * ec_wNAF_precompute_mult() | |
37c660ff BM |
577 | * creates an EC_PRE_COMP object with preprecomputed multiples of the generator |
578 | * for use with wNAF splitting as implemented in ec_wNAF_mul(). | |
0f113f3e | 579 | * |
37c660ff BM |
580 | * 'pre_comp->points' is an array of multiples of the generator |
581 | * of the following form: | |
582 | * points[0] = generator; | |
583 | * points[1] = 3 * generator; | |
584 | * ... | |
585 | * points[2^(w-1)-1] = (2^(w-1)-1) * generator; | |
586 | * points[2^(w-1)] = 2^blocksize * generator; | |
587 | * points[2^(w-1)+1] = 3 * 2^blocksize * generator; | |
588 | * ... | |
589 | * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator | |
590 | * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator | |
591 | * ... | |
592 | * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator | |
593 | * points[2^(w-1)*numblocks] = NULL | |
7793f30e | 594 | */ |
7793f30e | 595 | int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx) |
0f113f3e MC |
596 | { |
597 | const EC_POINT *generator; | |
598 | EC_POINT *tmp_point = NULL, *base = NULL, **var; | |
599 | BN_CTX *new_ctx = NULL; | |
600 | BIGNUM *order; | |
601 | size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num; | |
602 | EC_POINT **points = NULL; | |
603 | EC_PRE_COMP *pre_comp; | |
604 | int ret = 0; | |
605 | ||
606 | /* if there is an old EC_PRE_COMP object, throw it away */ | |
607 | EC_EX_DATA_free_data(&group->extra_data, ec_pre_comp_dup, | |
608 | ec_pre_comp_free, ec_pre_comp_clear_free); | |
609 | ||
610 | if ((pre_comp = ec_pre_comp_new(group)) == NULL) | |
611 | return 0; | |
612 | ||
613 | generator = EC_GROUP_get0_generator(group); | |
614 | if (generator == NULL) { | |
615 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); | |
616 | goto err; | |
617 | } | |
618 | ||
619 | if (ctx == NULL) { | |
620 | ctx = new_ctx = BN_CTX_new(); | |
621 | if (ctx == NULL) | |
622 | goto err; | |
623 | } | |
624 | ||
625 | BN_CTX_start(ctx); | |
626 | order = BN_CTX_get(ctx); | |
627 | if (order == NULL) | |
628 | goto err; | |
629 | ||
630 | if (!EC_GROUP_get_order(group, order, ctx)) | |
631 | goto err; | |
632 | if (BN_is_zero(order)) { | |
633 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); | |
634 | goto err; | |
635 | } | |
636 | ||
637 | bits = BN_num_bits(order); | |
638 | /* | |
639 | * The following parameters mean we precompute (approximately) one point | |
640 | * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other | |
641 | * bit lengths, other parameter combinations might provide better | |
642 | * efficiency. | |
643 | */ | |
644 | blocksize = 8; | |
645 | w = 4; | |
646 | if (EC_window_bits_for_scalar_size(bits) > w) { | |
647 | /* let's not make the window too small ... */ | |
648 | w = EC_window_bits_for_scalar_size(bits); | |
649 | } | |
650 | ||
651 | numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks | |
652 | * to use for wNAF | |
653 | * splitting */ | |
654 | ||
655 | pre_points_per_block = (size_t)1 << (w - 1); | |
656 | num = pre_points_per_block * numblocks; /* number of points to compute | |
657 | * and store */ | |
658 | ||
b4faea50 | 659 | points = OPENSSL_malloc(sizeof(*points) * (num + 1)); |
0f113f3e MC |
660 | if (!points) { |
661 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
662 | goto err; | |
663 | } | |
664 | ||
665 | var = points; | |
666 | var[num] = NULL; /* pivot */ | |
667 | for (i = 0; i < num; i++) { | |
668 | if ((var[i] = EC_POINT_new(group)) == NULL) { | |
669 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
670 | goto err; | |
671 | } | |
672 | } | |
673 | ||
75ebbd9a RS |
674 | if ((tmp_point = EC_POINT_new(group)) == NULL |
675 | || (base = EC_POINT_new(group)) == NULL) { | |
0f113f3e MC |
676 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); |
677 | goto err; | |
678 | } | |
679 | ||
680 | if (!EC_POINT_copy(base, generator)) | |
681 | goto err; | |
682 | ||
683 | /* do the precomputation */ | |
684 | for (i = 0; i < numblocks; i++) { | |
685 | size_t j; | |
686 | ||
687 | if (!EC_POINT_dbl(group, tmp_point, base, ctx)) | |
688 | goto err; | |
689 | ||
690 | if (!EC_POINT_copy(*var++, base)) | |
691 | goto err; | |
692 | ||
693 | for (j = 1; j < pre_points_per_block; j++, var++) { | |
694 | /* | |
695 | * calculate odd multiples of the current base point | |
696 | */ | |
697 | if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx)) | |
698 | goto err; | |
699 | } | |
700 | ||
701 | if (i < numblocks - 1) { | |
702 | /* | |
703 | * get the next base (multiply current one by 2^blocksize) | |
704 | */ | |
705 | size_t k; | |
706 | ||
707 | if (blocksize <= 2) { | |
708 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR); | |
709 | goto err; | |
710 | } | |
711 | ||
712 | if (!EC_POINT_dbl(group, base, tmp_point, ctx)) | |
713 | goto err; | |
714 | for (k = 2; k < blocksize; k++) { | |
715 | if (!EC_POINT_dbl(group, base, base, ctx)) | |
716 | goto err; | |
717 | } | |
718 | } | |
719 | } | |
720 | ||
721 | if (!EC_POINTs_make_affine(group, num, points, ctx)) | |
722 | goto err; | |
723 | ||
724 | pre_comp->group = group; | |
725 | pre_comp->blocksize = blocksize; | |
726 | pre_comp->numblocks = numblocks; | |
727 | pre_comp->w = w; | |
728 | pre_comp->points = points; | |
729 | points = NULL; | |
730 | pre_comp->num = num; | |
731 | ||
732 | if (!EC_EX_DATA_set_data(&group->extra_data, pre_comp, | |
733 | ec_pre_comp_dup, ec_pre_comp_free, | |
734 | ec_pre_comp_clear_free)) | |
735 | goto err; | |
736 | pre_comp = NULL; | |
737 | ||
738 | ret = 1; | |
38374911 | 739 | err: |
0f113f3e MC |
740 | if (ctx != NULL) |
741 | BN_CTX_end(ctx); | |
23a1d5e9 | 742 | BN_CTX_free(new_ctx); |
25aaa98a | 743 | ec_pre_comp_free(pre_comp); |
0f113f3e MC |
744 | if (points) { |
745 | EC_POINT **p; | |
746 | ||
747 | for (p = points; *p != NULL; p++) | |
748 | EC_POINT_free(*p); | |
749 | OPENSSL_free(points); | |
750 | } | |
8fdc3734 RS |
751 | EC_POINT_free(tmp_point); |
752 | EC_POINT_free(base); | |
0f113f3e MC |
753 | return ret; |
754 | } | |
7793f30e | 755 | |
37c660ff | 756 | int ec_wNAF_have_precompute_mult(const EC_GROUP *group) |
0f113f3e MC |
757 | { |
758 | if (EC_EX_DATA_get_data | |
759 | (group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, | |
760 | ec_pre_comp_clear_free) != NULL) | |
761 | return 1; | |
762 | else | |
763 | return 0; | |
764 | } |