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Fix free of garbage pointer. PR#3595
[thirdparty/openssl.git] / crypto / ec / ec_mult.c
1 /* crypto/ec/ec_mult.c */
2 /*
3 * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
4 */
5 /* ====================================================================
6 * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
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
13 * notice, this list of conditions and the following disclaimer.
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 */
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 */
63
64 #define OPENSSL_FIPSAPI
65
66 #include <string.h>
67
68 #include <openssl/err.h>
69
70 #include "ec_lcl.h"
71
72
73 /*
74 * This file implements the wNAF-based interleaving multi-exponentation method
75 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>);
76 * for multiplication with precomputation, we use wNAF splitting
77 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp>).
78 */
79
80
81
82
83 /* structure for precomputed multiples of the generator */
84 typedef struct ec_pre_comp_st {
85 const EC_GROUP *group; /* parent EC_GROUP object */
86 size_t blocksize; /* block size for wNAF splitting */
87 size_t numblocks; /* max. number of blocks for which we have precomputation */
88 size_t w; /* window size */
89 EC_POINT **points; /* array with pre-calculated multiples of generator:
90 * 'num' pointers to EC_POINT objects followed by a NULL */
91 size_t num; /* numblocks * 2^(w-1) */
92 int references;
93 } EC_PRE_COMP;
94
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)
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 {
110 ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
111 return ret;
112 }
113 ret->group = group;
114 ret->blocksize = 8; /* default */
115 ret->numblocks = 0;
116 ret->w = 4; /* default */
117 ret->points = NULL;
118 ret->num = 0;
119 ret->references = 1;
120 return ret;
121 }
122
123 static void *ec_pre_comp_dup(void *src_)
124 {
125 EC_PRE_COMP *src = src_;
126
127 /* no need to actually copy, these objects never change! */
128
129 CRYPTO_add(&src->references, 1, CRYPTO_LOCK_EC_PRE_COMP);
130
131 return src_;
132 }
133
134 static void ec_pre_comp_free(void *pre_)
135 {
136 int i;
137 EC_PRE_COMP *pre = pre_;
138
139 if (!pre)
140 return;
141
142 i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
143 if (i > 0)
144 return;
145
146 if (pre->points)
147 {
148 EC_POINT **p;
149
150 for (p = pre->points; *p != NULL; p++)
151 EC_POINT_free(*p);
152 OPENSSL_free(pre->points);
153 }
154 OPENSSL_free(pre);
155 }
156
157 static void ec_pre_comp_clear_free(void *pre_)
158 {
159 int i;
160 EC_PRE_COMP *pre = pre_;
161
162 if (!pre)
163 return;
164
165 i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
166 if (i > 0)
167 return;
168
169 if (pre->points)
170 {
171 EC_POINT **p;
172
173 for (p = pre->points; *p != NULL; p++)
174 {
175 EC_POINT_clear_free(*p);
176 OPENSSL_cleanse(p, sizeof *p);
177 }
178 OPENSSL_free(pre->points);
179 }
180 OPENSSL_cleanse(pre, sizeof *pre);
181 OPENSSL_free(pre);
182 }
183
184
185
186
187 /* Determine the modified width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'.
188 * This is an array r[] of values that are either zero or odd with an
189 * absolute value less than 2^w satisfying
190 * scalar = \sum_j r[j]*2^j
191 * where at most one of any w+1 consecutive digits is non-zero
192 * with the exception that the most significant digit may be only
193 * w-1 zeros away from that next non-zero digit.
194 */
195 static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
196 {
197 int window_val;
198 int ok = 0;
199 signed char *r = NULL;
200 int sign = 1;
201 int bit, next_bit, mask;
202 size_t len = 0, j;
203
204 if (BN_is_zero(scalar))
205 {
206 r = OPENSSL_malloc(1);
207 if (!r)
208 {
209 ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
210 goto err;
211 }
212 r[0] = 0;
213 *ret_len = 1;
214 return r;
215 }
216
217 if (w <= 0 || w > 7) /* 'signed char' can represent integers with absolute values less than 2^7 */
218 {
219 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
220 goto err;
221 }
222 bit = 1 << w; /* at most 128 */
223 next_bit = bit << 1; /* at most 256 */
224 mask = next_bit - 1; /* at most 255 */
225
226 if (BN_is_negative(scalar))
227 {
228 sign = -1;
229 }
230
231 if (scalar->d == NULL || scalar->top == 0)
232 {
233 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
234 goto err;
235 }
236
237 len = BN_num_bits(scalar);
238 r = OPENSSL_malloc(len + 1); /* modified wNAF may be one digit longer than binary representation
239 * (*ret_len will be set to the actual length, i.e. at most
240 * BN_num_bits(scalar) + 1) */
241 if (r == NULL)
242 {
243 ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
244 goto err;
245 }
246 window_val = scalar->d[0] & mask;
247 j = 0;
248 while ((window_val != 0) || (j + w + 1 < len)) /* if j+w+1 >= len, window_val will not increase */
249 {
250 int digit = 0;
251
252 /* 0 <= window_val <= 2^(w+1) */
253
254 if (window_val & 1)
255 {
256 /* 0 < window_val < 2^(w+1) */
257
258 if (window_val & bit)
259 {
260 digit = window_val - next_bit; /* -2^w < digit < 0 */
261
262 #if 1 /* modified wNAF */
263 if (j + w + 1 >= len)
264 {
265 /* special case for generating modified wNAFs:
266 * no new bits will be added into window_val,
267 * so using a positive digit here will decrease
268 * the total length of the representation */
269
270 digit = window_val & (mask >> 1); /* 0 < digit < 2^w */
271 }
272 #endif
273 }
274 else
275 {
276 digit = window_val; /* 0 < digit < 2^w */
277 }
278
279 if (digit <= -bit || digit >= bit || !(digit & 1))
280 {
281 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
282 goto err;
283 }
284
285 window_val -= digit;
286
287 /* now window_val is 0 or 2^(w+1) in standard wNAF generation;
288 * for modified window NAFs, it may also be 2^w
289 */
290 if (window_val != 0 && window_val != next_bit && window_val != bit)
291 {
292 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
293 goto err;
294 }
295 }
296
297 r[j++] = sign * digit;
298
299 window_val >>= 1;
300 window_val += bit * BN_is_bit_set(scalar, j + w);
301
302 if (window_val > next_bit)
303 {
304 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
305 goto err;
306 }
307 }
308
309 if (j > len + 1)
310 {
311 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
312 goto err;
313 }
314 len = j;
315 ok = 1;
316
317 err:
318 if (!ok)
319 {
320 OPENSSL_free(r);
321 r = NULL;
322 }
323 if (ok)
324 *ret_len = len;
325 return r;
326 }
327
328
329 /* TODO: table should be optimised for the wNAF-based implementation,
330 * sometimes smaller windows will give better performance
331 * (thus the boundaries should be increased)
332 */
333 #define EC_window_bits_for_scalar_size(b) \
334 ((size_t) \
335 ((b) >= 2000 ? 6 : \
336 (b) >= 800 ? 5 : \
337 (b) >= 300 ? 4 : \
338 (b) >= 70 ? 3 : \
339 (b) >= 20 ? 2 : \
340 1))
341
342 /* Compute
343 * \sum scalars[i]*points[i],
344 * also including
345 * scalar*generator
346 * in the addition if scalar != NULL
347 */
348 int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
349 size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx)
350 {
351 BN_CTX *new_ctx = NULL;
352 const EC_POINT *generator = NULL;
353 EC_POINT *tmp = NULL;
354 size_t totalnum;
355 size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */
356 size_t pre_points_per_block = 0;
357 size_t i, j;
358 int k;
359 int r_is_inverted = 0;
360 int r_is_at_infinity = 1;
361 size_t *wsize = NULL; /* individual window sizes */
362 signed char **wNAF = NULL; /* individual wNAFs */
363 size_t *wNAF_len = NULL;
364 size_t max_len = 0;
365 size_t num_val;
366 EC_POINT **val = NULL; /* precomputation */
367 EC_POINT **v;
368 EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or 'pre_comp->points' */
369 const EC_PRE_COMP *pre_comp = NULL;
370 int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be treated like other scalars,
371 * i.e. precomputation is not available */
372 int ret = 0;
373
374 if (group->meth != r->meth)
375 {
376 ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
377 return 0;
378 }
379
380 if ((scalar == NULL) && (num == 0))
381 {
382 return EC_POINT_set_to_infinity(group, r);
383 }
384
385 for (i = 0; i < num; i++)
386 {
387 if (group->meth != points[i]->meth)
388 {
389 ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
390 return 0;
391 }
392 }
393
394 if (ctx == NULL)
395 {
396 ctx = new_ctx = BN_CTX_new();
397 if (ctx == NULL)
398 goto err;
399 }
400
401 if (scalar != NULL)
402 {
403 generator = EC_GROUP_get0_generator(group);
404 if (generator == NULL)
405 {
406 ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR);
407 goto err;
408 }
409
410 /* look if we can use precomputed multiples of generator */
411
412 pre_comp = EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
413
414 if (pre_comp && pre_comp->numblocks && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == 0))
415 {
416 blocksize = pre_comp->blocksize;
417
418 /* determine maximum number of blocks that wNAF splitting may yield
419 * (NB: maximum wNAF length is bit length plus one) */
420 numblocks = (BN_num_bits(scalar) / blocksize) + 1;
421
422 /* we cannot use more blocks than we have precomputation for */
423 if (numblocks > pre_comp->numblocks)
424 numblocks = pre_comp->numblocks;
425
426 pre_points_per_block = (size_t)1 << (pre_comp->w - 1);
427
428 /* check that pre_comp looks sane */
429 if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block))
430 {
431 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
432 goto err;
433 }
434 }
435 else
436 {
437 /* can't use precomputation */
438 pre_comp = NULL;
439 numblocks = 1;
440 num_scalar = 1; /* treat 'scalar' like 'num'-th element of 'scalars' */
441 }
442 }
443
444 totalnum = num + numblocks;
445
446 wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]);
447 wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]);
448 wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space for pivot */
449 val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
450
451 /* Ensure wNAF is initialised in case we end up going to err */
452 if (wNAF) wNAF[0] = NULL; /* preliminary pivot */
453
454 if (!wsize || !wNAF_len || !wNAF || !val_sub)
455 {
456 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
457 goto err;
458 }
459
460 /* num_val will be the total number of temporarily precomputed points */
461 num_val = 0;
462
463 for (i = 0; i < num + num_scalar; i++)
464 {
465 size_t bits;
466
467 bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar);
468 wsize[i] = EC_window_bits_for_scalar_size(bits);
469 num_val += (size_t)1 << (wsize[i] - 1);
470 wNAF[i + 1] = NULL; /* make sure we always have a pivot */
471 wNAF[i] = compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], &wNAF_len[i]);
472 if (wNAF[i] == NULL)
473 goto err;
474 if (wNAF_len[i] > max_len)
475 max_len = wNAF_len[i];
476 }
477
478 if (numblocks)
479 {
480 /* we go here iff scalar != NULL */
481
482 if (pre_comp == NULL)
483 {
484 if (num_scalar != 1)
485 {
486 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
487 goto err;
488 }
489 /* we have already generated a wNAF for 'scalar' */
490 }
491 else
492 {
493 signed char *tmp_wNAF = NULL;
494 size_t tmp_len = 0;
495
496 if (num_scalar != 0)
497 {
498 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
499 goto err;
500 }
501
502 /* use the window size for which we have precomputation */
503 wsize[num] = pre_comp->w;
504 tmp_wNAF = compute_wNAF(scalar, wsize[num], &tmp_len);
505 if (!tmp_wNAF)
506 goto err;
507
508 if (tmp_len <= max_len)
509 {
510 /* One of the other wNAFs is at least as long
511 * as the wNAF belonging to the generator,
512 * so wNAF splitting will not buy us anything. */
513
514 numblocks = 1;
515 totalnum = num + 1; /* don't use wNAF splitting */
516 wNAF[num] = tmp_wNAF;
517 wNAF[num + 1] = NULL;
518 wNAF_len[num] = tmp_len;
519 if (tmp_len > max_len)
520 max_len = tmp_len;
521 /* pre_comp->points starts with the points that we need here: */
522 val_sub[num] = pre_comp->points;
523 }
524 else
525 {
526 /* don't include tmp_wNAF directly into wNAF array
527 * - use wNAF splitting and include the blocks */
528
529 signed char *pp;
530 EC_POINT **tmp_points;
531
532 if (tmp_len < numblocks * blocksize)
533 {
534 /* possibly we can do with fewer blocks than estimated */
535 numblocks = (tmp_len + blocksize - 1) / blocksize;
536 if (numblocks > pre_comp->numblocks)
537 {
538 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
539 goto err;
540 }
541 totalnum = num + numblocks;
542 }
543
544 /* split wNAF in 'numblocks' parts */
545 pp = tmp_wNAF;
546 tmp_points = pre_comp->points;
547
548 for (i = num; i < totalnum; i++)
549 {
550 if (i < totalnum - 1)
551 {
552 wNAF_len[i] = blocksize;
553 if (tmp_len < blocksize)
554 {
555 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
556 goto err;
557 }
558 tmp_len -= blocksize;
559 }
560 else
561 /* last block gets whatever is left
562 * (this could be more or less than 'blocksize'!) */
563 wNAF_len[i] = tmp_len;
564
565 wNAF[i + 1] = NULL;
566 wNAF[i] = OPENSSL_malloc(wNAF_len[i]);
567 if (wNAF[i] == NULL)
568 {
569 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
570 OPENSSL_free(tmp_wNAF);
571 goto err;
572 }
573 memcpy(wNAF[i], pp, wNAF_len[i]);
574 if (wNAF_len[i] > max_len)
575 max_len = wNAF_len[i];
576
577 if (*tmp_points == NULL)
578 {
579 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
580 OPENSSL_free(tmp_wNAF);
581 goto err;
582 }
583 val_sub[i] = tmp_points;
584 tmp_points += pre_points_per_block;
585 pp += blocksize;
586 }
587 OPENSSL_free(tmp_wNAF);
588 }
589 }
590 }
591
592 /* All points we precompute now go into a single array 'val'.
593 * 'val_sub[i]' is a pointer to the subarray for the i-th point,
594 * or to a subarray of 'pre_comp->points' if we already have precomputation. */
595 val = OPENSSL_malloc((num_val + 1) * sizeof val[0]);
596 if (val == NULL)
597 {
598 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
599 goto err;
600 }
601 val[num_val] = NULL; /* pivot element */
602
603 /* allocate points for precomputation */
604 v = val;
605 for (i = 0; i < num + num_scalar; i++)
606 {
607 val_sub[i] = v;
608 for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++)
609 {
610 *v = EC_POINT_new(group);
611 if (*v == NULL) goto err;
612 v++;
613 }
614 }
615 if (!(v == val + num_val))
616 {
617 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
618 goto err;
619 }
620
621 if (!(tmp = EC_POINT_new(group)))
622 goto err;
623
624 /* prepare precomputed values:
625 * val_sub[i][0] := points[i]
626 * val_sub[i][1] := 3 * points[i]
627 * val_sub[i][2] := 5 * points[i]
628 * ...
629 */
630 for (i = 0; i < num + num_scalar; i++)
631 {
632 if (i < num)
633 {
634 if (!EC_POINT_copy(val_sub[i][0], points[i])) goto err;
635 }
636 else
637 {
638 if (!EC_POINT_copy(val_sub[i][0], generator)) goto err;
639 }
640
641 if (wsize[i] > 1)
642 {
643 if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) goto err;
644 for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++)
645 {
646 if (!EC_POINT_add(group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) goto err;
647 }
648 }
649 }
650
651 #if 1 /* optional; EC_window_bits_for_scalar_size assumes we do this step */
652 if (!EC_POINTs_make_affine(group, num_val, val, ctx))
653 goto err;
654 #endif
655
656 r_is_at_infinity = 1;
657
658 for (k = max_len - 1; k >= 0; k--)
659 {
660 if (!r_is_at_infinity)
661 {
662 if (!EC_POINT_dbl(group, r, r, ctx)) goto err;
663 }
664
665 for (i = 0; i < totalnum; i++)
666 {
667 if (wNAF_len[i] > (size_t)k)
668 {
669 int digit = wNAF[i][k];
670 int is_neg;
671
672 if (digit)
673 {
674 is_neg = digit < 0;
675
676 if (is_neg)
677 digit = -digit;
678
679 if (is_neg != r_is_inverted)
680 {
681 if (!r_is_at_infinity)
682 {
683 if (!EC_POINT_invert(group, r, ctx)) goto err;
684 }
685 r_is_inverted = !r_is_inverted;
686 }
687
688 /* digit > 0 */
689
690 if (r_is_at_infinity)
691 {
692 if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) goto err;
693 r_is_at_infinity = 0;
694 }
695 else
696 {
697 if (!EC_POINT_add(group, r, r, val_sub[i][digit >> 1], ctx)) goto err;
698 }
699 }
700 }
701 }
702 }
703
704 if (r_is_at_infinity)
705 {
706 if (!EC_POINT_set_to_infinity(group, r)) goto err;
707 }
708 else
709 {
710 if (r_is_inverted)
711 if (!EC_POINT_invert(group, r, ctx)) goto err;
712 }
713
714 ret = 1;
715
716 err:
717 if (new_ctx != NULL)
718 BN_CTX_free(new_ctx);
719 if (tmp != NULL)
720 EC_POINT_free(tmp);
721 if (wsize != NULL)
722 OPENSSL_free(wsize);
723 if (wNAF_len != NULL)
724 OPENSSL_free(wNAF_len);
725 if (wNAF != NULL)
726 {
727 signed char **w;
728
729 for (w = wNAF; *w != NULL; w++)
730 OPENSSL_free(*w);
731
732 OPENSSL_free(wNAF);
733 }
734 if (val != NULL)
735 {
736 for (v = val; *v != NULL; v++)
737 EC_POINT_clear_free(*v);
738
739 OPENSSL_free(val);
740 }
741 if (val_sub != NULL)
742 {
743 OPENSSL_free(val_sub);
744 }
745 return ret;
746 }
747
748
749 /* ec_wNAF_precompute_mult()
750 * creates an EC_PRE_COMP object with preprecomputed multiples of the generator
751 * for use with wNAF splitting as implemented in ec_wNAF_mul().
752 *
753 * 'pre_comp->points' is an array of multiples of the generator
754 * of the following form:
755 * points[0] = generator;
756 * points[1] = 3 * generator;
757 * ...
758 * points[2^(w-1)-1] = (2^(w-1)-1) * generator;
759 * points[2^(w-1)] = 2^blocksize * generator;
760 * points[2^(w-1)+1] = 3 * 2^blocksize * generator;
761 * ...
762 * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator
763 * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator
764 * ...
765 * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator
766 * points[2^(w-1)*numblocks] = NULL
767 */
768 int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
769 {
770 const EC_POINT *generator;
771 EC_POINT *tmp_point = NULL, *base = NULL, **var;
772 BN_CTX *new_ctx = NULL;
773 BIGNUM *order;
774 size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num;
775 EC_POINT **points = NULL;
776 EC_PRE_COMP *pre_comp;
777 int ret = 0;
778
779 /* if there is an old EC_PRE_COMP object, throw it away */
780 EC_EX_DATA_free_data(&group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
781
782 if ((pre_comp = ec_pre_comp_new(group)) == NULL)
783 return 0;
784
785 generator = EC_GROUP_get0_generator(group);
786 if (generator == NULL)
787 {
788 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR);
789 goto err;
790 }
791
792 if (ctx == NULL)
793 {
794 ctx = new_ctx = BN_CTX_new();
795 if (ctx == NULL)
796 goto err;
797 }
798
799 BN_CTX_start(ctx);
800 order = BN_CTX_get(ctx);
801 if (order == NULL) goto err;
802
803 if (!EC_GROUP_get_order(group, order, ctx)) goto err;
804 if (BN_is_zero(order))
805 {
806 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER);
807 goto err;
808 }
809
810 bits = BN_num_bits(order);
811 /* The following parameters mean we precompute (approximately)
812 * one point per bit.
813 *
814 * TBD: The combination 8, 4 is perfect for 160 bits; for other
815 * bit lengths, other parameter combinations might provide better
816 * efficiency.
817 */
818 blocksize = 8;
819 w = 4;
820 if (EC_window_bits_for_scalar_size(bits) > w)
821 {
822 /* let's not make the window too small ... */
823 w = EC_window_bits_for_scalar_size(bits);
824 }
825
826 numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks to use for wNAF splitting */
827
828 pre_points_per_block = (size_t)1 << (w - 1);
829 num = pre_points_per_block * numblocks; /* number of points to compute and store */
830
831 points = OPENSSL_malloc(sizeof (EC_POINT*)*(num + 1));
832 if (!points)
833 {
834 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
835 goto err;
836 }
837
838 var = points;
839 var[num] = NULL; /* pivot */
840 for (i = 0; i < num; i++)
841 {
842 if ((var[i] = EC_POINT_new(group)) == NULL)
843 {
844 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
845 goto err;
846 }
847 }
848
849 if (!(tmp_point = EC_POINT_new(group)) || !(base = EC_POINT_new(group)))
850 {
851 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
852 goto err;
853 }
854
855 if (!EC_POINT_copy(base, generator))
856 goto err;
857
858 /* do the precomputation */
859 for (i = 0; i < numblocks; i++)
860 {
861 size_t j;
862
863 if (!EC_POINT_dbl(group, tmp_point, base, ctx))
864 goto err;
865
866 if (!EC_POINT_copy(*var++, base))
867 goto err;
868
869 for (j = 1; j < pre_points_per_block; j++, var++)
870 {
871 /* calculate odd multiples of the current base point */
872 if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx))
873 goto err;
874 }
875
876 if (i < numblocks - 1)
877 {
878 /* get the next base (multiply current one by 2^blocksize) */
879 size_t k;
880
881 if (blocksize <= 2)
882 {
883 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR);
884 goto err;
885 }
886
887 if (!EC_POINT_dbl(group, base, tmp_point, ctx))
888 goto err;
889 for (k = 2; k < blocksize; k++)
890 {
891 if (!EC_POINT_dbl(group,base,base,ctx))
892 goto err;
893 }
894 }
895 }
896
897 if (!EC_POINTs_make_affine(group, num, points, ctx))
898 goto err;
899
900 pre_comp->group = group;
901 pre_comp->blocksize = blocksize;
902 pre_comp->numblocks = numblocks;
903 pre_comp->w = w;
904 pre_comp->points = points;
905 points = NULL;
906 pre_comp->num = num;
907
908 if (!EC_EX_DATA_set_data(&group->extra_data, pre_comp,
909 ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free))
910 goto err;
911 pre_comp = NULL;
912
913 ret = 1;
914 err:
915 if (ctx != NULL)
916 BN_CTX_end(ctx);
917 if (new_ctx != NULL)
918 BN_CTX_free(new_ctx);
919 if (pre_comp)
920 ec_pre_comp_free(pre_comp);
921 if (points)
922 {
923 EC_POINT **p;
924
925 for (p = points; *p != NULL; p++)
926 EC_POINT_free(*p);
927 OPENSSL_free(points);
928 }
929 if (tmp_point)
930 EC_POINT_free(tmp_point);
931 if (base)
932 EC_POINT_free(base);
933 return ret;
934 }
935
936
937 int ec_wNAF_have_precompute_mult(const EC_GROUP *group)
938 {
939 if (EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free) != NULL)
940 return 1;
941 else
942 return 0;
943 }
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