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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 | /* ==================================================================== |
8ea16720 | 6 | * Copyright (c) 1998-2018 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 | |
ae5c8664 | 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 RL |
64 | #include <string.h> |
65 | ||
48fe4d62 BM |
66 | #include <openssl/err.h> |
67 | ||
65e81670 | 68 | #include "ec_lcl.h" |
48fe4d62 | 69 | |
37c660ff | 70 | /* |
54538204 RS |
71 | * This file implements the wNAF-based interleaving multi-exponentiation method |
72 | * Formerly at: | |
73 | * http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp | |
74 | * You might now find it here: | |
75 | * http://link.springer.com/chapter/10.1007%2F3-540-45537-X_13 | |
76 | * http://www.bmoeller.de/pdf/TI-01-08.multiexp.pdf | |
77 | * For multiplication with precomputation, we use wNAF splitting, formerly at: | |
78 | * http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp | |
37c660ff | 79 | */ |
48fe4d62 | 80 | |
37c660ff BM |
81 | /* structure for precomputed multiples of the generator */ |
82 | typedef struct ec_pre_comp_st { | |
ae5c8664 MC |
83 | const EC_GROUP *group; /* parent EC_GROUP object */ |
84 | size_t blocksize; /* block size for wNAF splitting */ | |
85 | size_t numblocks; /* max. number of blocks for which we have | |
86 | * precomputation */ | |
87 | size_t w; /* window size */ | |
88 | EC_POINT **points; /* array with pre-calculated multiples of | |
89 | * generator: 'num' pointers to EC_POINT | |
90 | * objects followed by a NULL */ | |
91 | size_t num; /* numblocks * 2^(w-1) */ | |
92 | int references; | |
37c660ff | 93 | } EC_PRE_COMP; |
ae5c8664 | 94 | |
37c660ff BM |
95 | /* functions to manage EC_PRE_COMP within the EC_GROUP extra_data framework */ |
96 | static void *ec_pre_comp_dup(void *); | |
97 | static void ec_pre_comp_free(void *); | |
98 | static void ec_pre_comp_clear_free(void *); | |
99 | ||
100 | static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group) | |
ae5c8664 MC |
101 | { |
102 | EC_PRE_COMP *ret = NULL; | |
103 | ||
104 | if (!group) | |
105 | return NULL; | |
106 | ||
107 | ret = (EC_PRE_COMP *)OPENSSL_malloc(sizeof(EC_PRE_COMP)); | |
108 | if (!ret) { | |
109 | ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE); | |
110 | return ret; | |
111 | } | |
112 | ret->group = group; | |
113 | ret->blocksize = 8; /* default */ | |
114 | ret->numblocks = 0; | |
115 | ret->w = 4; /* default */ | |
116 | ret->points = NULL; | |
117 | ret->num = 0; | |
118 | ret->references = 1; | |
119 | return ret; | |
120 | } | |
37c660ff BM |
121 | |
122 | static void *ec_pre_comp_dup(void *src_) | |
ae5c8664 MC |
123 | { |
124 | EC_PRE_COMP *src = src_; | |
37c660ff | 125 | |
ae5c8664 | 126 | /* no need to actually copy, these objects never change! */ |
37c660ff | 127 | |
ae5c8664 | 128 | CRYPTO_add(&src->references, 1, CRYPTO_LOCK_EC_PRE_COMP); |
37c660ff | 129 | |
ae5c8664 MC |
130 | return src_; |
131 | } | |
37c660ff BM |
132 | |
133 | static void ec_pre_comp_free(void *pre_) | |
ae5c8664 MC |
134 | { |
135 | int i; | |
136 | EC_PRE_COMP *pre = pre_; | |
37c660ff | 137 | |
ae5c8664 MC |
138 | if (!pre) |
139 | return; | |
ba729265 | 140 | |
ae5c8664 MC |
141 | i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP); |
142 | if (i > 0) | |
143 | return; | |
ba729265 | 144 | |
ae5c8664 MC |
145 | if (pre->points) { |
146 | EC_POINT **p; | |
37c660ff | 147 | |
ae5c8664 MC |
148 | for (p = pre->points; *p != NULL; p++) |
149 | EC_POINT_free(*p); | |
150 | OPENSSL_free(pre->points); | |
151 | } | |
152 | OPENSSL_free(pre); | |
153 | } | |
37c660ff BM |
154 | |
155 | static void ec_pre_comp_clear_free(void *pre_) | |
ae5c8664 MC |
156 | { |
157 | int i; | |
158 | EC_PRE_COMP *pre = pre_; | |
159 | ||
160 | if (!pre) | |
161 | return; | |
162 | ||
163 | i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP); | |
164 | if (i > 0) | |
165 | return; | |
166 | ||
167 | if (pre->points) { | |
168 | EC_POINT **p; | |
169 | ||
170 | for (p = pre->points; *p != NULL; p++) { | |
171 | EC_POINT_clear_free(*p); | |
c6738fd2 | 172 | OPENSSL_cleanse(p, sizeof(*p)); |
ae5c8664 MC |
173 | } |
174 | OPENSSL_free(pre->points); | |
175 | } | |
c6738fd2 | 176 | OPENSSL_cleanse(pre, sizeof(*pre)); |
ae5c8664 MC |
177 | OPENSSL_free(pre); |
178 | } | |
3ba1f111 | 179 | |
c695ebe2 MC |
180 | /*- |
181 | * Determine the modified width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'. | |
3ba1f111 BM |
182 | * This is an array r[] of values that are either zero or odd with an |
183 | * absolute value less than 2^w satisfying | |
184 | * scalar = \sum_j r[j]*2^j | |
2c8d0dcc BM |
185 | * where at most one of any w+1 consecutive digits is non-zero |
186 | * with the exception that the most significant digit may be only | |
187 | * w-1 zeros away from that next non-zero digit. | |
3ba1f111 | 188 | */ |
2c8d0dcc | 189 | static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len) |
ae5c8664 MC |
190 | { |
191 | int window_val; | |
192 | int ok = 0; | |
193 | signed char *r = NULL; | |
194 | int sign = 1; | |
195 | int bit, next_bit, mask; | |
196 | size_t len = 0, j; | |
197 | ||
198 | if (BN_is_zero(scalar)) { | |
199 | r = OPENSSL_malloc(1); | |
200 | if (!r) { | |
201 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE); | |
202 | goto err; | |
203 | } | |
204 | r[0] = 0; | |
205 | *ret_len = 1; | |
206 | return r; | |
207 | } | |
208 | ||
209 | if (w <= 0 || w > 7) { /* 'signed char' can represent integers with | |
210 | * absolute values less than 2^7 */ | |
211 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); | |
212 | goto err; | |
213 | } | |
214 | bit = 1 << w; /* at most 128 */ | |
215 | next_bit = bit << 1; /* at most 256 */ | |
216 | mask = next_bit - 1; /* at most 255 */ | |
217 | ||
218 | if (BN_is_negative(scalar)) { | |
219 | sign = -1; | |
220 | } | |
221 | ||
222 | if (scalar->d == NULL || scalar->top == 0) { | |
223 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); | |
224 | goto err; | |
225 | } | |
226 | ||
227 | len = BN_num_bits(scalar); | |
228 | r = OPENSSL_malloc(len + 1); /* modified wNAF may be one digit longer | |
229 | * than binary representation (*ret_len will | |
230 | * be set to the actual length, i.e. at most | |
231 | * BN_num_bits(scalar) + 1) */ | |
232 | if (r == NULL) { | |
233 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE); | |
234 | goto err; | |
235 | } | |
236 | window_val = scalar->d[0] & mask; | |
237 | j = 0; | |
238 | while ((window_val != 0) || (j + w + 1 < len)) { /* if j+w+1 >= len, | |
239 | * window_val will not | |
240 | * increase */ | |
241 | int digit = 0; | |
242 | ||
243 | /* 0 <= window_val <= 2^(w+1) */ | |
244 | ||
245 | if (window_val & 1) { | |
246 | /* 0 < window_val < 2^(w+1) */ | |
247 | ||
248 | if (window_val & bit) { | |
249 | digit = window_val - next_bit; /* -2^w < digit < 0 */ | |
250 | ||
251 | #if 1 /* modified wNAF */ | |
252 | if (j + w + 1 >= len) { | |
253 | /* | |
254 | * special case for generating modified wNAFs: no new | |
255 | * bits will be added into window_val, so using a | |
256 | * positive digit here will decrease the total length of | |
257 | * the representation | |
258 | */ | |
259 | ||
260 | digit = window_val & (mask >> 1); /* 0 < digit < 2^w */ | |
261 | } | |
2c8d0dcc | 262 | #endif |
ae5c8664 MC |
263 | } else { |
264 | digit = window_val; /* 0 < digit < 2^w */ | |
265 | } | |
266 | ||
267 | if (digit <= -bit || digit >= bit || !(digit & 1)) { | |
268 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); | |
269 | goto err; | |
270 | } | |
271 | ||
272 | window_val -= digit; | |
273 | ||
274 | /* | |
275 | * now window_val is 0 or 2^(w+1) in standard wNAF generation; | |
276 | * for modified window NAFs, it may also be 2^w | |
277 | */ | |
278 | if (window_val != 0 && window_val != next_bit | |
279 | && window_val != bit) { | |
280 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); | |
281 | goto err; | |
282 | } | |
283 | } | |
284 | ||
285 | r[j++] = sign * digit; | |
286 | ||
287 | window_val >>= 1; | |
288 | window_val += bit * BN_is_bit_set(scalar, j + w); | |
289 | ||
290 | if (window_val > next_bit) { | |
291 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); | |
292 | goto err; | |
293 | } | |
294 | } | |
295 | ||
296 | if (j > len + 1) { | |
297 | ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); | |
298 | goto err; | |
299 | } | |
300 | len = j; | |
301 | ok = 1; | |
3ba1f111 BM |
302 | |
303 | err: | |
ae5c8664 MC |
304 | if (!ok) { |
305 | OPENSSL_free(r); | |
306 | r = NULL; | |
307 | } | |
308 | if (ok) | |
309 | *ret_len = len; | |
310 | return r; | |
311 | } | |
312 | ||
b18162a7 BB |
313 | #define EC_POINT_BN_set_flags(P, flags) do { \ |
314 | BN_set_flags(&(P)->X, (flags)); \ | |
315 | BN_set_flags(&(P)->Y, (flags)); \ | |
316 | BN_set_flags(&(P)->Z, (flags)); \ | |
317 | } while(0) | |
318 | ||
319 | /*- | |
320 | * This functions computes (in constant time) a point multiplication over the | |
321 | * EC group. | |
322 | * | |
323 | * At a high level, it is Montgomery ladder with conditional swaps. | |
324 | * | |
325 | * It performs either a fixed scalar point multiplication | |
326 | * (scalar * generator) | |
327 | * when point is NULL, or a generic scalar point multiplication | |
328 | * (scalar * point) | |
329 | * when point is not NULL. | |
330 | * | |
331 | * scalar should be in the range [0,n) otherwise all constant time bets are off. | |
332 | * | |
333 | * NB: This says nothing about EC_POINT_add and EC_POINT_dbl, | |
334 | * which of course are not constant time themselves. | |
335 | * | |
336 | * The product is stored in r. | |
337 | * | |
338 | * Returns 1 on success, 0 otherwise. | |
339 | */ | |
340 | static int ec_mul_consttime(const EC_GROUP *group, EC_POINT *r, | |
341 | const BIGNUM *scalar, const EC_POINT *point, | |
342 | BN_CTX *ctx) | |
343 | { | |
344 | int i, cardinality_bits, group_top, kbit, pbit, Z_is_one; | |
345 | EC_POINT *s = NULL; | |
346 | BIGNUM *k = NULL; | |
347 | BIGNUM *lambda = NULL; | |
348 | BIGNUM *cardinality = NULL; | |
349 | BN_CTX *new_ctx = NULL; | |
350 | int ret = 0; | |
351 | ||
352 | if (ctx == NULL && (ctx = new_ctx = BN_CTX_new()) == NULL) | |
353 | return 0; | |
354 | ||
355 | BN_CTX_start(ctx); | |
356 | ||
357 | s = EC_POINT_new(group); | |
358 | if (s == NULL) | |
359 | goto err; | |
360 | ||
361 | if (point == NULL) { | |
362 | if (!EC_POINT_copy(s, group->generator)) | |
363 | goto err; | |
364 | } else { | |
365 | if (!EC_POINT_copy(s, point)) | |
366 | goto err; | |
367 | } | |
368 | ||
369 | EC_POINT_BN_set_flags(s, BN_FLG_CONSTTIME); | |
370 | ||
371 | cardinality = BN_CTX_get(ctx); | |
372 | lambda = BN_CTX_get(ctx); | |
373 | k = BN_CTX_get(ctx); | |
374 | if (k == NULL || !BN_mul(cardinality, &group->order, &group->cofactor, ctx)) | |
375 | goto err; | |
376 | ||
377 | /* | |
378 | * Group cardinalities are often on a word boundary. | |
379 | * So when we pad the scalar, some timing diff might | |
380 | * pop if it needs to be expanded due to carries. | |
381 | * So expand ahead of time. | |
382 | */ | |
383 | cardinality_bits = BN_num_bits(cardinality); | |
384 | group_top = cardinality->top; | |
385 | if ((bn_wexpand(k, group_top + 2) == NULL) | |
386 | || (bn_wexpand(lambda, group_top + 2) == NULL)) | |
387 | goto err; | |
388 | ||
389 | if (!BN_copy(k, scalar)) | |
390 | goto err; | |
391 | ||
392 | BN_set_flags(k, BN_FLG_CONSTTIME); | |
393 | ||
394 | if ((BN_num_bits(k) > cardinality_bits) || (BN_is_negative(k))) { | |
395 | /*- | |
396 | * this is an unusual input, and we don't guarantee | |
397 | * constant-timeness | |
398 | */ | |
399 | if (!BN_nnmod(k, k, cardinality, ctx)) | |
400 | goto err; | |
401 | } | |
402 | ||
403 | if (!BN_add(lambda, k, cardinality)) | |
404 | goto err; | |
405 | BN_set_flags(lambda, BN_FLG_CONSTTIME); | |
406 | if (!BN_add(k, lambda, cardinality)) | |
407 | goto err; | |
408 | /* | |
409 | * lambda := scalar + cardinality | |
410 | * k := scalar + 2*cardinality | |
411 | */ | |
412 | kbit = BN_is_bit_set(lambda, cardinality_bits); | |
413 | BN_consttime_swap(kbit, k, lambda, group_top + 2); | |
414 | ||
415 | group_top = group->field.top; | |
416 | if ((bn_wexpand(&s->X, group_top) == NULL) | |
417 | || (bn_wexpand(&s->Y, group_top) == NULL) | |
418 | || (bn_wexpand(&s->Z, group_top) == NULL) | |
419 | || (bn_wexpand(&r->X, group_top) == NULL) | |
420 | || (bn_wexpand(&r->Y, group_top) == NULL) | |
421 | || (bn_wexpand(&r->Z, group_top) == NULL)) | |
422 | goto err; | |
423 | ||
424 | /* top bit is a 1, in a fixed pos */ | |
425 | if (!EC_POINT_copy(r, s)) | |
426 | goto err; | |
427 | ||
428 | EC_POINT_BN_set_flags(r, BN_FLG_CONSTTIME); | |
429 | ||
430 | if (!EC_POINT_dbl(group, s, s, ctx)) | |
431 | goto err; | |
432 | ||
433 | pbit = 0; | |
434 | ||
435 | #define EC_POINT_CSWAP(c, a, b, w, t) do { \ | |
436 | BN_consttime_swap(c, &(a)->X, &(b)->X, w); \ | |
437 | BN_consttime_swap(c, &(a)->Y, &(b)->Y, w); \ | |
438 | BN_consttime_swap(c, &(a)->Z, &(b)->Z, w); \ | |
439 | t = ((a)->Z_is_one ^ (b)->Z_is_one) & (c); \ | |
440 | (a)->Z_is_one ^= (t); \ | |
441 | (b)->Z_is_one ^= (t); \ | |
442 | } while(0) | |
443 | ||
444 | /*- | |
445 | * The ladder step, with branches, is | |
446 | * | |
447 | * k[i] == 0: S = add(R, S), R = dbl(R) | |
448 | * k[i] == 1: R = add(S, R), S = dbl(S) | |
449 | * | |
450 | * Swapping R, S conditionally on k[i] leaves you with state | |
451 | * | |
452 | * k[i] == 0: T, U = R, S | |
453 | * k[i] == 1: T, U = S, R | |
454 | * | |
455 | * Then perform the ECC ops. | |
456 | * | |
457 | * U = add(T, U) | |
458 | * T = dbl(T) | |
459 | * | |
460 | * Which leaves you with state | |
461 | * | |
462 | * k[i] == 0: U = add(R, S), T = dbl(R) | |
463 | * k[i] == 1: U = add(S, R), T = dbl(S) | |
464 | * | |
465 | * Swapping T, U conditionally on k[i] leaves you with state | |
466 | * | |
467 | * k[i] == 0: R, S = T, U | |
468 | * k[i] == 1: R, S = U, T | |
469 | * | |
470 | * Which leaves you with state | |
471 | * | |
472 | * k[i] == 0: S = add(R, S), R = dbl(R) | |
473 | * k[i] == 1: R = add(S, R), S = dbl(S) | |
474 | * | |
475 | * So we get the same logic, but instead of a branch it's a | |
476 | * conditional swap, followed by ECC ops, then another conditional swap. | |
477 | * | |
478 | * Optimization: The end of iteration i and start of i-1 looks like | |
479 | * | |
480 | * ... | |
481 | * CSWAP(k[i], R, S) | |
482 | * ECC | |
483 | * CSWAP(k[i], R, S) | |
484 | * (next iteration) | |
485 | * CSWAP(k[i-1], R, S) | |
486 | * ECC | |
487 | * CSWAP(k[i-1], R, S) | |
488 | * ... | |
489 | * | |
490 | * So instead of two contiguous swaps, you can merge the condition | |
491 | * bits and do a single swap. | |
492 | * | |
493 | * k[i] k[i-1] Outcome | |
494 | * 0 0 No Swap | |
495 | * 0 1 Swap | |
496 | * 1 0 Swap | |
497 | * 1 1 No Swap | |
498 | * | |
499 | * This is XOR. pbit tracks the previous bit of k. | |
500 | */ | |
501 | ||
502 | for (i = cardinality_bits - 1; i >= 0; i--) { | |
503 | kbit = BN_is_bit_set(k, i) ^ pbit; | |
504 | EC_POINT_CSWAP(kbit, r, s, group_top, Z_is_one); | |
505 | if (!EC_POINT_add(group, s, r, s, ctx)) | |
506 | goto err; | |
507 | if (!EC_POINT_dbl(group, r, r, ctx)) | |
508 | goto err; | |
509 | /* | |
510 | * pbit logic merges this cswap with that of the | |
511 | * next iteration | |
512 | */ | |
513 | pbit ^= kbit; | |
514 | } | |
515 | /* one final cswap to move the right value into r */ | |
516 | EC_POINT_CSWAP(pbit, r, s, group_top, Z_is_one); | |
517 | #undef EC_POINT_CSWAP | |
518 | ||
519 | ret = 1; | |
520 | ||
521 | err: | |
522 | EC_POINT_free(s); | |
523 | BN_CTX_end(ctx); | |
524 | BN_CTX_free(new_ctx); | |
525 | ||
526 | return ret; | |
527 | } | |
528 | ||
529 | #undef EC_POINT_BN_set_flags | |
530 | ||
ae5c8664 MC |
531 | /* |
532 | * TODO: table should be optimised for the wNAF-based implementation, | |
533 | * sometimes smaller windows will give better performance (thus the | |
534 | * boundaries should be increased) | |
c05940ed | 535 | */ |
3ba1f111 | 536 | #define EC_window_bits_for_scalar_size(b) \ |
ae5c8664 MC |
537 | ((size_t) \ |
538 | ((b) >= 2000 ? 6 : \ | |
539 | (b) >= 800 ? 5 : \ | |
540 | (b) >= 300 ? 4 : \ | |
541 | (b) >= 70 ? 3 : \ | |
542 | (b) >= 20 ? 2 : \ | |
543 | 1)) | |
3ba1f111 | 544 | |
c695ebe2 MC |
545 | /*- |
546 | * Compute | |
3ba1f111 BM |
547 | * \sum scalars[i]*points[i], |
548 | * also including | |
549 | * scalar*generator | |
550 | * in the addition if scalar != NULL | |
551 | */ | |
7793f30e | 552 | int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, |
ae5c8664 MC |
553 | size_t num, const EC_POINT *points[], const BIGNUM *scalars[], |
554 | BN_CTX *ctx) | |
555 | { | |
556 | BN_CTX *new_ctx = NULL; | |
557 | const EC_POINT *generator = NULL; | |
558 | EC_POINT *tmp = NULL; | |
559 | size_t totalnum; | |
560 | size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */ | |
561 | size_t pre_points_per_block = 0; | |
562 | size_t i, j; | |
563 | int k; | |
564 | int r_is_inverted = 0; | |
565 | int r_is_at_infinity = 1; | |
566 | size_t *wsize = NULL; /* individual window sizes */ | |
567 | signed char **wNAF = NULL; /* individual wNAFs */ | |
568 | size_t *wNAF_len = NULL; | |
569 | size_t max_len = 0; | |
570 | size_t num_val; | |
571 | EC_POINT **val = NULL; /* precomputation */ | |
572 | EC_POINT **v; | |
573 | EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or | |
574 | * 'pre_comp->points' */ | |
575 | const EC_PRE_COMP *pre_comp = NULL; | |
576 | int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be | |
577 | * treated like other scalars, i.e. | |
578 | * precomputation is not available */ | |
579 | int ret = 0; | |
580 | ||
581 | if (group->meth != r->meth) { | |
582 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
583 | return 0; | |
584 | } | |
585 | ||
586 | if ((scalar == NULL) && (num == 0)) { | |
587 | return EC_POINT_set_to_infinity(group, r); | |
588 | } | |
589 | ||
b18162a7 BB |
590 | if (!BN_is_zero(&group->order) && !BN_is_zero(&group->cofactor)) { |
591 | /*- | |
592 | * Handle the common cases where the scalar is secret, enforcing a constant | |
593 | * time scalar multiplication algorithm. | |
594 | */ | |
595 | if ((scalar != NULL) && (num == 0)) { | |
596 | /*- | |
597 | * In this case we want to compute scalar * GeneratorPoint: this | |
598 | * codepath is reached most prominently by (ephemeral) key generation | |
599 | * of EC cryptosystems (i.e. ECDSA keygen and sign setup, ECDH | |
600 | * keygen/first half), where the scalar is always secret. This is why | |
601 | * we ignore if BN_FLG_CONSTTIME is actually set and we always call the | |
602 | * constant time version. | |
603 | */ | |
604 | return ec_mul_consttime(group, r, scalar, NULL, ctx); | |
605 | } | |
606 | if ((scalar == NULL) && (num == 1)) { | |
607 | /*- | |
608 | * In this case we want to compute scalar * GenericPoint: this codepath | |
609 | * is reached most prominently by the second half of ECDH, where the | |
610 | * secret scalar is multiplied by the peer's public point. To protect | |
611 | * the secret scalar, we ignore if BN_FLG_CONSTTIME is actually set and | |
612 | * we always call the constant time version. | |
613 | */ | |
614 | return ec_mul_consttime(group, r, scalars[0], points[0], ctx); | |
615 | } | |
616 | } | |
617 | ||
ae5c8664 MC |
618 | for (i = 0; i < num; i++) { |
619 | if (group->meth != points[i]->meth) { | |
620 | ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); | |
621 | return 0; | |
622 | } | |
623 | } | |
624 | ||
625 | if (ctx == NULL) { | |
626 | ctx = new_ctx = BN_CTX_new(); | |
627 | if (ctx == NULL) | |
628 | goto err; | |
629 | } | |
630 | ||
631 | if (scalar != NULL) { | |
632 | generator = EC_GROUP_get0_generator(group); | |
633 | if (generator == NULL) { | |
634 | ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR); | |
635 | goto err; | |
636 | } | |
637 | ||
638 | /* look if we can use precomputed multiples of generator */ | |
639 | ||
640 | pre_comp = | |
641 | EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, | |
642 | ec_pre_comp_free, ec_pre_comp_clear_free); | |
643 | ||
644 | if (pre_comp && pre_comp->numblocks | |
645 | && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == | |
646 | 0)) { | |
647 | blocksize = pre_comp->blocksize; | |
648 | ||
649 | /* | |
650 | * determine maximum number of blocks that wNAF splitting may | |
651 | * yield (NB: maximum wNAF length is bit length plus one) | |
652 | */ | |
653 | numblocks = (BN_num_bits(scalar) / blocksize) + 1; | |
654 | ||
655 | /* | |
656 | * we cannot use more blocks than we have precomputation for | |
657 | */ | |
658 | if (numblocks > pre_comp->numblocks) | |
659 | numblocks = pre_comp->numblocks; | |
660 | ||
661 | pre_points_per_block = (size_t)1 << (pre_comp->w - 1); | |
662 | ||
663 | /* check that pre_comp looks sane */ | |
664 | if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block)) { | |
665 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
666 | goto err; | |
667 | } | |
668 | } else { | |
669 | /* can't use precomputation */ | |
670 | pre_comp = NULL; | |
671 | numblocks = 1; | |
672 | num_scalar = 1; /* treat 'scalar' like 'num'-th element of | |
673 | * 'scalars' */ | |
674 | } | |
675 | } | |
676 | ||
677 | totalnum = num + numblocks; | |
678 | ||
c6738fd2 RS |
679 | wsize = OPENSSL_malloc(totalnum * sizeof(wsize[0])); |
680 | wNAF_len = OPENSSL_malloc(totalnum * sizeof(wNAF_len[0])); | |
681 | /* include space for pivot */ | |
682 | wNAF = OPENSSL_malloc((totalnum + 1) * sizeof(wNAF[0])); | |
683 | val_sub = OPENSSL_malloc(totalnum * sizeof(val_sub[0])); | |
ae5c8664 MC |
684 | |
685 | /* Ensure wNAF is initialised in case we end up going to err */ | |
686 | if (wNAF) | |
687 | wNAF[0] = NULL; /* preliminary pivot */ | |
688 | ||
689 | if (!wsize || !wNAF_len || !wNAF || !val_sub) { | |
690 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
691 | goto err; | |
692 | } | |
693 | ||
694 | /* | |
695 | * num_val will be the total number of temporarily precomputed points | |
696 | */ | |
697 | num_val = 0; | |
698 | ||
699 | for (i = 0; i < num + num_scalar; i++) { | |
700 | size_t bits; | |
701 | ||
702 | bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar); | |
703 | wsize[i] = EC_window_bits_for_scalar_size(bits); | |
704 | num_val += (size_t)1 << (wsize[i] - 1); | |
705 | wNAF[i + 1] = NULL; /* make sure we always have a pivot */ | |
706 | wNAF[i] = | |
707 | compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], | |
708 | &wNAF_len[i]); | |
709 | if (wNAF[i] == NULL) | |
710 | goto err; | |
711 | if (wNAF_len[i] > max_len) | |
712 | max_len = wNAF_len[i]; | |
713 | } | |
714 | ||
715 | if (numblocks) { | |
716 | /* we go here iff scalar != NULL */ | |
717 | ||
718 | if (pre_comp == NULL) { | |
719 | if (num_scalar != 1) { | |
720 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
721 | goto err; | |
722 | } | |
723 | /* we have already generated a wNAF for 'scalar' */ | |
724 | } else { | |
725 | signed char *tmp_wNAF = NULL; | |
726 | size_t tmp_len = 0; | |
727 | ||
728 | if (num_scalar != 0) { | |
729 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
730 | goto err; | |
731 | } | |
732 | ||
733 | /* | |
734 | * use the window size for which we have precomputation | |
735 | */ | |
736 | wsize[num] = pre_comp->w; | |
737 | tmp_wNAF = compute_wNAF(scalar, wsize[num], &tmp_len); | |
738 | if (!tmp_wNAF) | |
739 | goto err; | |
740 | ||
741 | if (tmp_len <= max_len) { | |
742 | /* | |
743 | * One of the other wNAFs is at least as long as the wNAF | |
744 | * belonging to the generator, so wNAF splitting will not buy | |
745 | * us anything. | |
746 | */ | |
747 | ||
748 | numblocks = 1; | |
749 | totalnum = num + 1; /* don't use wNAF splitting */ | |
750 | wNAF[num] = tmp_wNAF; | |
751 | wNAF[num + 1] = NULL; | |
752 | wNAF_len[num] = tmp_len; | |
753 | if (tmp_len > max_len) | |
754 | max_len = tmp_len; | |
755 | /* | |
756 | * pre_comp->points starts with the points that we need here: | |
757 | */ | |
758 | val_sub[num] = pre_comp->points; | |
759 | } else { | |
760 | /* | |
761 | * don't include tmp_wNAF directly into wNAF array - use wNAF | |
762 | * splitting and include the blocks | |
763 | */ | |
764 | ||
765 | signed char *pp; | |
766 | EC_POINT **tmp_points; | |
767 | ||
768 | if (tmp_len < numblocks * blocksize) { | |
769 | /* | |
770 | * possibly we can do with fewer blocks than estimated | |
771 | */ | |
772 | numblocks = (tmp_len + blocksize - 1) / blocksize; | |
773 | if (numblocks > pre_comp->numblocks) { | |
774 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
775 | goto err; | |
776 | } | |
777 | totalnum = num + numblocks; | |
778 | } | |
779 | ||
780 | /* split wNAF in 'numblocks' parts */ | |
781 | pp = tmp_wNAF; | |
782 | tmp_points = pre_comp->points; | |
783 | ||
784 | for (i = num; i < totalnum; i++) { | |
785 | if (i < totalnum - 1) { | |
786 | wNAF_len[i] = blocksize; | |
787 | if (tmp_len < blocksize) { | |
788 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
789 | goto err; | |
790 | } | |
791 | tmp_len -= blocksize; | |
792 | } else | |
793 | /* | |
794 | * last block gets whatever is left (this could be | |
795 | * more or less than 'blocksize'!) | |
796 | */ | |
797 | wNAF_len[i] = tmp_len; | |
798 | ||
799 | wNAF[i + 1] = NULL; | |
800 | wNAF[i] = OPENSSL_malloc(wNAF_len[i]); | |
801 | if (wNAF[i] == NULL) { | |
802 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
803 | OPENSSL_free(tmp_wNAF); | |
804 | goto err; | |
805 | } | |
806 | memcpy(wNAF[i], pp, wNAF_len[i]); | |
807 | if (wNAF_len[i] > max_len) | |
808 | max_len = wNAF_len[i]; | |
809 | ||
810 | if (*tmp_points == NULL) { | |
811 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
812 | OPENSSL_free(tmp_wNAF); | |
813 | goto err; | |
814 | } | |
815 | val_sub[i] = tmp_points; | |
816 | tmp_points += pre_points_per_block; | |
817 | pp += blocksize; | |
818 | } | |
819 | OPENSSL_free(tmp_wNAF); | |
820 | } | |
821 | } | |
822 | } | |
823 | ||
824 | /* | |
825 | * All points we precompute now go into a single array 'val'. | |
826 | * 'val_sub[i]' is a pointer to the subarray for the i-th point, or to a | |
827 | * subarray of 'pre_comp->points' if we already have precomputation. | |
828 | */ | |
c6738fd2 | 829 | val = OPENSSL_malloc((num_val + 1) * sizeof(val[0])); |
ae5c8664 MC |
830 | if (val == NULL) { |
831 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE); | |
832 | goto err; | |
833 | } | |
834 | val[num_val] = NULL; /* pivot element */ | |
835 | ||
836 | /* allocate points for precomputation */ | |
837 | v = val; | |
838 | for (i = 0; i < num + num_scalar; i++) { | |
839 | val_sub[i] = v; | |
840 | for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
841 | *v = EC_POINT_new(group); | |
842 | if (*v == NULL) | |
843 | goto err; | |
844 | v++; | |
845 | } | |
846 | } | |
847 | if (!(v == val + num_val)) { | |
848 | ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR); | |
849 | goto err; | |
850 | } | |
851 | ||
852 | if (!(tmp = EC_POINT_new(group))) | |
853 | goto err; | |
854 | ||
83975c80 MC |
855 | /*- |
856 | * prepare precomputed values: | |
857 | * val_sub[i][0] := points[i] | |
858 | * val_sub[i][1] := 3 * points[i] | |
859 | * val_sub[i][2] := 5 * points[i] | |
860 | * ... | |
861 | */ | |
ae5c8664 MC |
862 | for (i = 0; i < num + num_scalar; i++) { |
863 | if (i < num) { | |
864 | if (!EC_POINT_copy(val_sub[i][0], points[i])) | |
865 | goto err; | |
866 | } else { | |
867 | if (!EC_POINT_copy(val_sub[i][0], generator)) | |
868 | goto err; | |
869 | } | |
870 | ||
871 | if (wsize[i] > 1) { | |
872 | if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) | |
873 | goto err; | |
874 | for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++) { | |
875 | if (!EC_POINT_add | |
876 | (group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) | |
877 | goto err; | |
878 | } | |
879 | } | |
880 | } | |
881 | ||
882 | #if 1 /* optional; EC_window_bits_for_scalar_size | |
883 | * assumes we do this step */ | |
884 | if (!EC_POINTs_make_affine(group, num_val, val, ctx)) | |
885 | goto err; | |
3ba1f111 BM |
886 | #endif |
887 | ||
ae5c8664 MC |
888 | r_is_at_infinity = 1; |
889 | ||
890 | for (k = max_len - 1; k >= 0; k--) { | |
891 | if (!r_is_at_infinity) { | |
892 | if (!EC_POINT_dbl(group, r, r, ctx)) | |
893 | goto err; | |
894 | } | |
895 | ||
896 | for (i = 0; i < totalnum; i++) { | |
897 | if (wNAF_len[i] > (size_t)k) { | |
898 | int digit = wNAF[i][k]; | |
899 | int is_neg; | |
900 | ||
901 | if (digit) { | |
902 | is_neg = digit < 0; | |
903 | ||
904 | if (is_neg) | |
905 | digit = -digit; | |
906 | ||
907 | if (is_neg != r_is_inverted) { | |
908 | if (!r_is_at_infinity) { | |
909 | if (!EC_POINT_invert(group, r, ctx)) | |
910 | goto err; | |
911 | } | |
912 | r_is_inverted = !r_is_inverted; | |
913 | } | |
914 | ||
915 | /* digit > 0 */ | |
916 | ||
917 | if (r_is_at_infinity) { | |
918 | if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) | |
919 | goto err; | |
920 | r_is_at_infinity = 0; | |
921 | } else { | |
922 | if (!EC_POINT_add | |
923 | (group, r, r, val_sub[i][digit >> 1], ctx)) | |
924 | goto err; | |
925 | } | |
926 | } | |
927 | } | |
928 | } | |
929 | } | |
930 | ||
931 | if (r_is_at_infinity) { | |
932 | if (!EC_POINT_set_to_infinity(group, r)) | |
933 | goto err; | |
934 | } else { | |
935 | if (r_is_inverted) | |
936 | if (!EC_POINT_invert(group, r, ctx)) | |
937 | goto err; | |
938 | } | |
939 | ||
940 | ret = 1; | |
3ba1f111 BM |
941 | |
942 | err: | |
ae5c8664 MC |
943 | if (new_ctx != NULL) |
944 | BN_CTX_free(new_ctx); | |
945 | if (tmp != NULL) | |
946 | EC_POINT_free(tmp); | |
947 | if (wsize != NULL) | |
948 | OPENSSL_free(wsize); | |
949 | if (wNAF_len != NULL) | |
950 | OPENSSL_free(wNAF_len); | |
951 | if (wNAF != NULL) { | |
952 | signed char **w; | |
953 | ||
954 | for (w = wNAF; *w != NULL; w++) | |
955 | OPENSSL_free(*w); | |
956 | ||
957 | OPENSSL_free(wNAF); | |
958 | } | |
959 | if (val != NULL) { | |
960 | for (v = val; *v != NULL; v++) | |
961 | EC_POINT_clear_free(*v); | |
962 | ||
963 | OPENSSL_free(val); | |
964 | } | |
965 | if (val_sub != NULL) { | |
966 | OPENSSL_free(val_sub); | |
967 | } | |
968 | return ret; | |
969 | } | |
38374911 | 970 | |
6977c7e2 TH |
971 | /*- |
972 | * ec_wNAF_precompute_mult() | |
37c660ff BM |
973 | * creates an EC_PRE_COMP object with preprecomputed multiples of the generator |
974 | * for use with wNAF splitting as implemented in ec_wNAF_mul(). | |
ae5c8664 | 975 | * |
37c660ff BM |
976 | * 'pre_comp->points' is an array of multiples of the generator |
977 | * of the following form: | |
978 | * points[0] = generator; | |
979 | * points[1] = 3 * generator; | |
980 | * ... | |
981 | * points[2^(w-1)-1] = (2^(w-1)-1) * generator; | |
982 | * points[2^(w-1)] = 2^blocksize * generator; | |
983 | * points[2^(w-1)+1] = 3 * 2^blocksize * generator; | |
984 | * ... | |
985 | * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator | |
986 | * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator | |
987 | * ... | |
988 | * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator | |
989 | * points[2^(w-1)*numblocks] = NULL | |
7793f30e | 990 | */ |
7793f30e | 991 | int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx) |
ae5c8664 MC |
992 | { |
993 | const EC_POINT *generator; | |
994 | EC_POINT *tmp_point = NULL, *base = NULL, **var; | |
995 | BN_CTX *new_ctx = NULL; | |
996 | BIGNUM *order; | |
997 | size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num; | |
998 | EC_POINT **points = NULL; | |
999 | EC_PRE_COMP *pre_comp; | |
1000 | int ret = 0; | |
1001 | ||
1002 | /* if there is an old EC_PRE_COMP object, throw it away */ | |
1003 | EC_EX_DATA_free_data(&group->extra_data, ec_pre_comp_dup, | |
1004 | ec_pre_comp_free, ec_pre_comp_clear_free); | |
1005 | ||
1006 | if ((pre_comp = ec_pre_comp_new(group)) == NULL) | |
1007 | return 0; | |
1008 | ||
1009 | generator = EC_GROUP_get0_generator(group); | |
1010 | if (generator == NULL) { | |
1011 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); | |
1012 | goto err; | |
1013 | } | |
1014 | ||
1015 | if (ctx == NULL) { | |
1016 | ctx = new_ctx = BN_CTX_new(); | |
1017 | if (ctx == NULL) | |
1018 | goto err; | |
1019 | } | |
1020 | ||
1021 | BN_CTX_start(ctx); | |
1022 | order = BN_CTX_get(ctx); | |
1023 | if (order == NULL) | |
1024 | goto err; | |
1025 | ||
1026 | if (!EC_GROUP_get_order(group, order, ctx)) | |
1027 | goto err; | |
1028 | if (BN_is_zero(order)) { | |
1029 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); | |
1030 | goto err; | |
1031 | } | |
1032 | ||
1033 | bits = BN_num_bits(order); | |
1034 | /* | |
1035 | * The following parameters mean we precompute (approximately) one point | |
1036 | * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other | |
1037 | * bit lengths, other parameter combinations might provide better | |
1038 | * efficiency. | |
1039 | */ | |
1040 | blocksize = 8; | |
1041 | w = 4; | |
1042 | if (EC_window_bits_for_scalar_size(bits) > w) { | |
1043 | /* let's not make the window too small ... */ | |
1044 | w = EC_window_bits_for_scalar_size(bits); | |
1045 | } | |
1046 | ||
1047 | numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks | |
1048 | * to use for wNAF | |
1049 | * splitting */ | |
1050 | ||
1051 | pre_points_per_block = (size_t)1 << (w - 1); | |
1052 | num = pre_points_per_block * numblocks; /* number of points to compute | |
1053 | * and store */ | |
1054 | ||
1055 | points = OPENSSL_malloc(sizeof(EC_POINT *) * (num + 1)); | |
1056 | if (!points) { | |
1057 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
1058 | goto err; | |
1059 | } | |
1060 | ||
1061 | var = points; | |
1062 | var[num] = NULL; /* pivot */ | |
1063 | for (i = 0; i < num; i++) { | |
1064 | if ((var[i] = EC_POINT_new(group)) == NULL) { | |
1065 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
1066 | goto err; | |
1067 | } | |
1068 | } | |
1069 | ||
1070 | if (!(tmp_point = EC_POINT_new(group)) || !(base = EC_POINT_new(group))) { | |
1071 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); | |
1072 | goto err; | |
1073 | } | |
1074 | ||
1075 | if (!EC_POINT_copy(base, generator)) | |
1076 | goto err; | |
1077 | ||
1078 | /* do the precomputation */ | |
1079 | for (i = 0; i < numblocks; i++) { | |
1080 | size_t j; | |
1081 | ||
1082 | if (!EC_POINT_dbl(group, tmp_point, base, ctx)) | |
1083 | goto err; | |
1084 | ||
1085 | if (!EC_POINT_copy(*var++, base)) | |
1086 | goto err; | |
1087 | ||
1088 | for (j = 1; j < pre_points_per_block; j++, var++) { | |
1089 | /* | |
1090 | * calculate odd multiples of the current base point | |
1091 | */ | |
1092 | if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx)) | |
1093 | goto err; | |
1094 | } | |
1095 | ||
1096 | if (i < numblocks - 1) { | |
1097 | /* | |
1098 | * get the next base (multiply current one by 2^blocksize) | |
1099 | */ | |
1100 | size_t k; | |
1101 | ||
1102 | if (blocksize <= 2) { | |
1103 | ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR); | |
1104 | goto err; | |
1105 | } | |
1106 | ||
1107 | if (!EC_POINT_dbl(group, base, tmp_point, ctx)) | |
1108 | goto err; | |
1109 | for (k = 2; k < blocksize; k++) { | |
1110 | if (!EC_POINT_dbl(group, base, base, ctx)) | |
1111 | goto err; | |
1112 | } | |
1113 | } | |
1114 | } | |
1115 | ||
1116 | if (!EC_POINTs_make_affine(group, num, points, ctx)) | |
1117 | goto err; | |
1118 | ||
1119 | pre_comp->group = group; | |
1120 | pre_comp->blocksize = blocksize; | |
1121 | pre_comp->numblocks = numblocks; | |
1122 | pre_comp->w = w; | |
1123 | pre_comp->points = points; | |
1124 | points = NULL; | |
1125 | pre_comp->num = num; | |
1126 | ||
1127 | if (!EC_EX_DATA_set_data(&group->extra_data, pre_comp, | |
1128 | ec_pre_comp_dup, ec_pre_comp_free, | |
1129 | ec_pre_comp_clear_free)) | |
1130 | goto err; | |
1131 | pre_comp = NULL; | |
1132 | ||
1133 | ret = 1; | |
38374911 | 1134 | err: |
ae5c8664 MC |
1135 | if (ctx != NULL) |
1136 | BN_CTX_end(ctx); | |
1137 | if (new_ctx != NULL) | |
1138 | BN_CTX_free(new_ctx); | |
1139 | if (pre_comp) | |
1140 | ec_pre_comp_free(pre_comp); | |
1141 | if (points) { | |
1142 | EC_POINT **p; | |
1143 | ||
1144 | for (p = points; *p != NULL; p++) | |
1145 | EC_POINT_free(*p); | |
1146 | OPENSSL_free(points); | |
1147 | } | |
1148 | if (tmp_point) | |
1149 | EC_POINT_free(tmp_point); | |
1150 | if (base) | |
1151 | EC_POINT_free(base); | |
1152 | return ret; | |
1153 | } | |
7793f30e | 1154 | |
37c660ff | 1155 | int ec_wNAF_have_precompute_mult(const EC_GROUP *group) |
ae5c8664 MC |
1156 | { |
1157 | if (EC_EX_DATA_get_data | |
1158 | (group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, | |
1159 | ec_pre_comp_clear_free) != NULL) | |
1160 | return 1; | |
1161 | else | |
1162 | return 0; | |
1163 | } |