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-rw-r--r--src/lib/libcrypto/ec/ec_mult.c673
1 files changed, 563 insertions, 110 deletions
diff --git a/src/lib/libcrypto/ec/ec_mult.c b/src/lib/libcrypto/ec/ec_mult.c
index 16822a73cf..2ba173ef36 100644
--- a/src/lib/libcrypto/ec/ec_mult.c
+++ b/src/lib/libcrypto/ec/ec_mult.c
@@ -1,6 +1,9 @@
1/* 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 */
2/* ==================================================================== 5/* ====================================================================
3 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved. 6 * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
4 * 7 *
5 * Redistribution and use in source and binary forms, with or without 8 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions 9 * modification, are permitted provided that the following conditions
@@ -52,41 +55,161 @@
52 * Hudson (tjh@cryptsoft.com). 55 * Hudson (tjh@cryptsoft.com).
53 * 56 *
54 */ 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#include <string.h>
55 65
56#include <openssl/err.h> 66#include <openssl/err.h>
57 67
58#include "ec_lcl.h" 68#include "ec_lcl.h"
59 69
60 70
61/* TODO: optional precomputation of multiples of the generator */ 71/*
72 * This file implements the wNAF-based interleaving multi-exponentation method
73 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>);
74 * for multiplication with precomputation, we use wNAF splitting
75 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp>).
76 */
62 77
63 78
64 79
65/* 80
66 * wNAF-based interleaving multi-exponentation method 81/* structure for precomputed multiples of the generator */
67 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>) 82typedef struct ec_pre_comp_st {
68 */ 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 precomputation */
86 size_t w; /* window size */
87 EC_POINT **points; /* array with pre-calculated multiples of generator:
88 * 'num' pointers to EC_POINT objects followed by a NULL */
89 size_t num; /* numblocks * 2^(w-1) */
90 int references;
91} EC_PRE_COMP;
92
93/* functions to manage EC_PRE_COMP within the EC_GROUP extra_data framework */
94static void *ec_pre_comp_dup(void *);
95static void ec_pre_comp_free(void *);
96static void ec_pre_comp_clear_free(void *);
97
98static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group)
99 {
100 EC_PRE_COMP *ret = NULL;
101
102 if (!group)
103 return NULL;
104
105 ret = (EC_PRE_COMP *)OPENSSL_malloc(sizeof(EC_PRE_COMP));
106 if (!ret)
107 {
108 ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
109 return ret;
110 }
111 ret->group = group;
112 ret->blocksize = 8; /* default */
113 ret->numblocks = 0;
114 ret->w = 4; /* default */
115 ret->points = NULL;
116 ret->num = 0;
117 ret->references = 1;
118 return ret;
119 }
120
121static void *ec_pre_comp_dup(void *src_)
122 {
123 EC_PRE_COMP *src = src_;
124
125 /* no need to actually copy, these objects never change! */
126
127 CRYPTO_add(&src->references, 1, CRYPTO_LOCK_EC_PRE_COMP);
128
129 return src_;
130 }
131
132static void ec_pre_comp_free(void *pre_)
133 {
134 int i;
135 EC_PRE_COMP *pre = pre_;
136
137 if (!pre)
138 return;
139
140 i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
141 if (i > 0)
142 return;
143
144 if (pre->points)
145 {
146 EC_POINT **p;
147
148 for (p = pre->points; *p != NULL; p++)
149 EC_POINT_free(*p);
150 OPENSSL_free(pre->points);
151 }
152 OPENSSL_free(pre);
153 }
154
155static void ec_pre_comp_clear_free(void *pre_)
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 {
169 EC_POINT **p;
170
171 for (p = pre->points; *p != NULL; p++)
172 EC_POINT_clear_free(*p);
173 OPENSSL_cleanse(pre->points, sizeof pre->points);
174 OPENSSL_free(pre->points);
175 }
176 OPENSSL_cleanse(pre, sizeof pre);
177 OPENSSL_free(pre);
178 }
179
69 180
70 181
71/* Determine the width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'. 182
183/* Determine the modified width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'.
72 * This is an array r[] of values that are either zero or odd with an 184 * This is an array r[] of values that are either zero or odd with an
73 * absolute value less than 2^w satisfying 185 * absolute value less than 2^w satisfying
74 * scalar = \sum_j r[j]*2^j 186 * scalar = \sum_j r[j]*2^j
75 * where at most one of any w+1 consecutive digits is non-zero. 187 * where at most one of any w+1 consecutive digits is non-zero
188 * with the exception that the most significant digit may be only
189 * w-1 zeros away from that next non-zero digit.
76 */ 190 */
77static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, BN_CTX *ctx) 191static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
78 { 192 {
79 BIGNUM *c; 193 int window_val;
80 int ok = 0; 194 int ok = 0;
81 signed char *r = NULL; 195 signed char *r = NULL;
82 int sign = 1; 196 int sign = 1;
83 int bit, next_bit, mask; 197 int bit, next_bit, mask;
84 size_t len = 0, j; 198 size_t len = 0, j;
85 199
86 BN_CTX_start(ctx); 200 if (BN_is_zero(scalar))
87 c = BN_CTX_get(ctx); 201 {
88 if (c == NULL) goto err; 202 r = OPENSSL_malloc(1);
89 203 if (!r)
204 {
205 ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
206 goto err;
207 }
208 r[0] = 0;
209 *ret_len = 1;
210 return r;
211 }
212
90 if (w <= 0 || w > 7) /* 'signed char' can represent integers with absolute values less than 2^7 */ 213 if (w <= 0 || w > 7) /* 'signed char' can represent integers with absolute values less than 2^7 */
91 { 214 {
92 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); 215 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
@@ -96,60 +219,90 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B
96 next_bit = bit << 1; /* at most 256 */ 219 next_bit = bit << 1; /* at most 256 */
97 mask = next_bit - 1; /* at most 255 */ 220 mask = next_bit - 1; /* at most 255 */
98 221
99 if (!BN_copy(c, scalar)) goto err; 222 if (BN_is_negative(scalar))
100 if (c->neg)
101 { 223 {
102 sign = -1; 224 sign = -1;
103 c->neg = 0;
104 } 225 }
105 226
106 len = BN_num_bits(c) + 1; /* wNAF may be one digit longer than binary representation */ 227 len = BN_num_bits(scalar);
107 r = OPENSSL_malloc(len); 228 r = OPENSSL_malloc(len + 1); /* modified wNAF may be one digit longer than binary representation
108 if (r == NULL) goto err; 229 * (*ret_len will be set to the actual length, i.e. at most
230 * BN_num_bits(scalar) + 1) */
231 if (r == NULL)
232 {
233 ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
234 goto err;
235 }
109 236
237 if (scalar->d == NULL || scalar->top == 0)
238 {
239 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
240 goto err;
241 }
242 window_val = scalar->d[0] & mask;
110 j = 0; 243 j = 0;
111 while (!BN_is_zero(c)) 244 while ((window_val != 0) || (j + w + 1 < len)) /* if j+w+1 >= len, window_val will not increase */
112 { 245 {
113 int u = 0; 246 int digit = 0;
114 247
115 if (BN_is_odd(c)) 248 /* 0 <= window_val <= 2^(w+1) */
249
250 if (window_val & 1)
116 { 251 {
117 if (c->d == NULL || c->top == 0) 252 /* 0 < window_val < 2^(w+1) */
253
254 if (window_val & bit)
118 { 255 {
119 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); 256 digit = window_val - next_bit; /* -2^w < digit < 0 */
120 goto err; 257
258#if 1 /* modified wNAF */
259 if (j + w + 1 >= len)
260 {
261 /* special case for generating modified wNAFs:
262 * no new bits will be added into window_val,
263 * so using a positive digit here will decrease
264 * the total length of the representation */
265
266 digit = window_val & (mask >> 1); /* 0 < digit < 2^w */
267 }
268#endif
121 } 269 }
122 u = c->d[0] & mask; 270 else
123 if (u & bit)
124 { 271 {
125 u -= next_bit; 272 digit = window_val; /* 0 < digit < 2^w */
126 /* u < 0 */
127 if (!BN_add_word(c, -u)) goto err;
128 } 273 }
129 else 274
275 if (digit <= -bit || digit >= bit || !(digit & 1))
130 { 276 {
131 /* u > 0 */ 277 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
132 if (!BN_sub_word(c, u)) goto err; 278 goto err;
133 } 279 }
134 280
135 if (u <= -bit || u >= bit || !(u & 1) || c->neg) 281 window_val -= digit;
282
283 /* now window_val is 0 or 2^(w+1) in standard wNAF generation;
284 * for modified window NAFs, it may also be 2^w
285 */
286 if (window_val != 0 && window_val != next_bit && window_val != bit)
136 { 287 {
137 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); 288 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
138 goto err; 289 goto err;
139 } 290 }
140 } 291 }
141 292
142 r[j++] = sign * u; 293 r[j++] = sign * digit;
143 294
144 if (BN_is_odd(c)) 295 window_val >>= 1;
296 window_val += bit * BN_is_bit_set(scalar, j + w);
297
298 if (window_val > next_bit)
145 { 299 {
146 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); 300 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
147 goto err; 301 goto err;
148 } 302 }
149 if (!BN_rshift1(c, c)) goto err;
150 } 303 }
151 304
152 if (j > len) 305 if (j > len + 1)
153 { 306 {
154 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); 307 ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
155 goto err; 308 goto err;
@@ -158,7 +311,6 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B
158 ok = 1; 311 ok = 1;
159 312
160 err: 313 err:
161 BN_CTX_end(ctx);
162 if (!ok) 314 if (!ok)
163 { 315 {
164 OPENSSL_free(r); 316 OPENSSL_free(r);
@@ -181,7 +333,7 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B
181 (b) >= 300 ? 4 : \ 333 (b) >= 300 ? 4 : \
182 (b) >= 70 ? 3 : \ 334 (b) >= 70 ? 3 : \
183 (b) >= 20 ? 2 : \ 335 (b) >= 20 ? 2 : \
184 1)) 336 1))
185 337
186/* Compute 338/* Compute
187 * \sum scalars[i]*points[i], 339 * \sum scalars[i]*points[i],
@@ -189,13 +341,15 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B
189 * scalar*generator 341 * scalar*generator
190 * in the addition if scalar != NULL 342 * in the addition if scalar != NULL
191 */ 343 */
192int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, 344int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
193 size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx) 345 size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx)
194 { 346 {
195 BN_CTX *new_ctx = NULL; 347 BN_CTX *new_ctx = NULL;
196 EC_POINT *generator = NULL; 348 const EC_POINT *generator = NULL;
197 EC_POINT *tmp = NULL; 349 EC_POINT *tmp = NULL;
198 size_t totalnum; 350 size_t totalnum;
351 size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */
352 size_t pre_points_per_block = 0;
199 size_t i, j; 353 size_t i, j;
200 int k; 354 int k;
201 int r_is_inverted = 0; 355 int r_is_inverted = 0;
@@ -207,12 +361,15 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
207 size_t num_val; 361 size_t num_val;
208 EC_POINT **val = NULL; /* precomputation */ 362 EC_POINT **val = NULL; /* precomputation */
209 EC_POINT **v; 363 EC_POINT **v;
210 EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' */ 364 EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or 'pre_comp->points' */
365 const EC_PRE_COMP *pre_comp = NULL;
366 int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be treated like other scalars,
367 * i.e. precomputation is not available */
211 int ret = 0; 368 int ret = 0;
212 369
213 if (group->meth != r->meth) 370 if (group->meth != r->meth)
214 { 371 {
215 ECerr(EC_F_EC_POINTS_MUL, EC_R_INCOMPATIBLE_OBJECTS); 372 ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
216 return 0; 373 return 0;
217 } 374 }
218 375
@@ -221,59 +378,226 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
221 return EC_POINT_set_to_infinity(group, r); 378 return EC_POINT_set_to_infinity(group, r);
222 } 379 }
223 380
224 if (scalar != NULL) 381 for (i = 0; i < num; i++)
225 { 382 {
226 generator = EC_GROUP_get0_generator(group); 383 if (group->meth != points[i]->meth)
227 if (generator == NULL)
228 { 384 {
229 ECerr(EC_F_EC_POINTS_MUL, EC_R_UNDEFINED_GENERATOR); 385 ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
230 return 0; 386 return 0;
231 } 387 }
232 } 388 }
233 389
234 for (i = 0; i < num; i++) 390 if (ctx == NULL)
235 { 391 {
236 if (group->meth != points[i]->meth) 392 ctx = new_ctx = BN_CTX_new();
393 if (ctx == NULL)
394 goto err;
395 }
396
397 if (scalar != NULL)
398 {
399 generator = EC_GROUP_get0_generator(group);
400 if (generator == NULL)
237 { 401 {
238 ECerr(EC_F_EC_POINTS_MUL, EC_R_INCOMPATIBLE_OBJECTS); 402 ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR);
239 return 0; 403 goto err;
240 } 404 }
241 } 405
406 /* look if we can use precomputed multiples of generator */
407
408 pre_comp = EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
409
410 if (pre_comp && pre_comp->numblocks && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == 0))
411 {
412 blocksize = pre_comp->blocksize;
242 413
243 totalnum = num + (scalar != NULL); 414 /* determine maximum number of blocks that wNAF splitting may yield
415 * (NB: maximum wNAF length is bit length plus one) */
416 numblocks = (BN_num_bits(scalar) / blocksize) + 1;
244 417
245 wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]); 418 /* we cannot use more blocks than we have precomputation for */
419 if (numblocks > pre_comp->numblocks)
420 numblocks = pre_comp->numblocks;
421
422 pre_points_per_block = 1u << (pre_comp->w - 1);
423
424 /* check that pre_comp looks sane */
425 if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block))
426 {
427 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
428 goto err;
429 }
430 }
431 else
432 {
433 /* can't use precomputation */
434 pre_comp = NULL;
435 numblocks = 1;
436 num_scalar = 1; /* treat 'scalar' like 'num'-th element of 'scalars' */
437 }
438 }
439
440 totalnum = num + numblocks;
441
442 wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]);
246 wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]); 443 wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]);
247 wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); 444 wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space for pivot */
248 if (wNAF != NULL) 445 val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
446
447 if (!wsize || !wNAF_len || !wNAF || !val_sub)
249 { 448 {
250 wNAF[0] = NULL; /* preliminary pivot */ 449 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
450 goto err;
251 } 451 }
252 if (wsize == NULL || wNAF_len == NULL || wNAF == NULL) goto err;
253 452
254 /* num_val := total number of points to precompute */ 453 wNAF[0] = NULL; /* preliminary pivot */
454
455 /* num_val will be the total number of temporarily precomputed points */
255 num_val = 0; 456 num_val = 0;
256 for (i = 0; i < totalnum; i++) 457
458 for (i = 0; i < num + num_scalar; i++)
257 { 459 {
258 size_t bits; 460 size_t bits;
259 461
260 bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar); 462 bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar);
261 wsize[i] = EC_window_bits_for_scalar_size(bits); 463 wsize[i] = EC_window_bits_for_scalar_size(bits);
262 num_val += 1u << (wsize[i] - 1); 464 num_val += 1u << (wsize[i] - 1);
465 wNAF[i + 1] = NULL; /* make sure we always have a pivot */
466 wNAF[i] = compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], &wNAF_len[i]);
467 if (wNAF[i] == NULL)
468 goto err;
469 if (wNAF_len[i] > max_len)
470 max_len = wNAF_len[i];
471 }
472
473 if (numblocks)
474 {
475 /* we go here iff scalar != NULL */
476
477 if (pre_comp == NULL)
478 {
479 if (num_scalar != 1)
480 {
481 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
482 goto err;
483 }
484 /* we have already generated a wNAF for 'scalar' */
485 }
486 else
487 {
488 signed char *tmp_wNAF = NULL;
489 size_t tmp_len = 0;
490
491 if (num_scalar != 0)
492 {
493 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
494 goto err;
495 }
496
497 /* use the window size for which we have precomputation */
498 wsize[num] = pre_comp->w;
499 tmp_wNAF = compute_wNAF(scalar, wsize[num], &tmp_len);
500 if (!tmp_wNAF)
501 goto err;
502
503 if (tmp_len <= max_len)
504 {
505 /* One of the other wNAFs is at least as long
506 * as the wNAF belonging to the generator,
507 * so wNAF splitting will not buy us anything. */
508
509 numblocks = 1;
510 totalnum = num + 1; /* don't use wNAF splitting */
511 wNAF[num] = tmp_wNAF;
512 wNAF[num + 1] = NULL;
513 wNAF_len[num] = tmp_len;
514 if (tmp_len > max_len)
515 max_len = tmp_len;
516 /* pre_comp->points starts with the points that we need here: */
517 val_sub[num] = pre_comp->points;
518 }
519 else
520 {
521 /* don't include tmp_wNAF directly into wNAF array
522 * - use wNAF splitting and include the blocks */
523
524 signed char *pp;
525 EC_POINT **tmp_points;
526
527 if (tmp_len < numblocks * blocksize)
528 {
529 /* possibly we can do with fewer blocks than estimated */
530 numblocks = (tmp_len + blocksize - 1) / blocksize;
531 if (numblocks > pre_comp->numblocks)
532 {
533 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
534 goto err;
535 }
536 totalnum = num + numblocks;
537 }
538
539 /* split wNAF in 'numblocks' parts */
540 pp = tmp_wNAF;
541 tmp_points = pre_comp->points;
542
543 for (i = num; i < totalnum; i++)
544 {
545 if (i < totalnum - 1)
546 {
547 wNAF_len[i] = blocksize;
548 if (tmp_len < blocksize)
549 {
550 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
551 goto err;
552 }
553 tmp_len -= blocksize;
554 }
555 else
556 /* last block gets whatever is left
557 * (this could be more or less than 'blocksize'!) */
558 wNAF_len[i] = tmp_len;
559
560 wNAF[i + 1] = NULL;
561 wNAF[i] = OPENSSL_malloc(wNAF_len[i]);
562 if (wNAF[i] == NULL)
563 {
564 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
565 OPENSSL_free(tmp_wNAF);
566 goto err;
567 }
568 memcpy(wNAF[i], pp, wNAF_len[i]);
569 if (wNAF_len[i] > max_len)
570 max_len = wNAF_len[i];
571
572 if (*tmp_points == NULL)
573 {
574 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
575 OPENSSL_free(tmp_wNAF);
576 goto err;
577 }
578 val_sub[i] = tmp_points;
579 tmp_points += pre_points_per_block;
580 pp += blocksize;
581 }
582 OPENSSL_free(tmp_wNAF);
583 }
584 }
263 } 585 }
264 586
265 /* all precomputed points go into a single array 'val', 587 /* All points we precompute now go into a single array 'val'.
266 * 'val_sub[i]' is a pointer to the subarray for the i-th point */ 588 * 'val_sub[i]' is a pointer to the subarray for the i-th point,
589 * or to a subarray of 'pre_comp->points' if we already have precomputation. */
267 val = OPENSSL_malloc((num_val + 1) * sizeof val[0]); 590 val = OPENSSL_malloc((num_val + 1) * sizeof val[0]);
268 if (val == NULL) goto err; 591 if (val == NULL)
592 {
593 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
594 goto err;
595 }
269 val[num_val] = NULL; /* pivot element */ 596 val[num_val] = NULL; /* pivot element */
270 597
271 val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
272 if (val_sub == NULL) goto err;
273
274 /* allocate points for precomputation */ 598 /* allocate points for precomputation */
275 v = val; 599 v = val;
276 for (i = 0; i < totalnum; i++) 600 for (i = 0; i < num + num_scalar; i++)
277 { 601 {
278 val_sub[i] = v; 602 val_sub[i] = v;
279 for (j = 0; j < (1u << (wsize[i] - 1)); j++) 603 for (j = 0; j < (1u << (wsize[i] - 1)); j++)
@@ -285,19 +609,12 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
285 } 609 }
286 if (!(v == val + num_val)) 610 if (!(v == val + num_val))
287 { 611 {
288 ECerr(EC_F_EC_POINTS_MUL, ERR_R_INTERNAL_ERROR); 612 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
289 goto err; 613 goto err;
290 } 614 }
291 615
292 if (ctx == NULL) 616 if (!(tmp = EC_POINT_new(group)))
293 { 617 goto err;
294 ctx = new_ctx = BN_CTX_new();
295 if (ctx == NULL)
296 goto err;
297 }
298
299 tmp = EC_POINT_new(group);
300 if (tmp == NULL) goto err;
301 618
302 /* prepare precomputed values: 619 /* prepare precomputed values:
303 * val_sub[i][0] := points[i] 620 * val_sub[i][0] := points[i]
@@ -305,7 +622,7 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
305 * val_sub[i][2] := 5 * points[i] 622 * val_sub[i][2] := 5 * points[i]
306 * ... 623 * ...
307 */ 624 */
308 for (i = 0; i < totalnum; i++) 625 for (i = 0; i < num + num_scalar; i++)
309 { 626 {
310 if (i < num) 627 if (i < num)
311 { 628 {
@@ -324,16 +641,11 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
324 if (!EC_POINT_add(group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) goto err; 641 if (!EC_POINT_add(group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) goto err;
325 } 642 }
326 } 643 }
327
328 wNAF[i + 1] = NULL; /* make sure we always have a pivot */
329 wNAF[i] = compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], &wNAF_len[i], ctx);
330 if (wNAF[i] == NULL) goto err;
331 if (wNAF_len[i] > max_len)
332 max_len = wNAF_len[i];
333 } 644 }
334 645
335#if 1 /* optional; EC_window_bits_for_scalar_size assumes we do this step */ 646#if 1 /* optional; EC_window_bits_for_scalar_size assumes we do this step */
336 if (!EC_POINTs_make_affine(group, num_val, val, ctx)) goto err; 647 if (!EC_POINTs_make_affine(group, num_val, val, ctx))
648 goto err;
337#endif 649#endif
338 650
339 r_is_at_infinity = 1; 651 r_is_at_infinity = 1;
@@ -429,57 +741,198 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
429 } 741 }
430 742
431 743
432int EC_POINT_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *g_scalar, const EC_POINT *point, const BIGNUM *p_scalar, BN_CTX *ctx) 744/* ec_wNAF_precompute_mult()
433 { 745 * creates an EC_PRE_COMP object with preprecomputed multiples of the generator
434 const EC_POINT *points[1]; 746 * for use with wNAF splitting as implemented in ec_wNAF_mul().
435 const BIGNUM *scalars[1]; 747 *
436 748 * 'pre_comp->points' is an array of multiples of the generator
437 points[0] = point; 749 * of the following form:
438 scalars[0] = p_scalar; 750 * points[0] = generator;
439 751 * points[1] = 3 * generator;
440 return EC_POINTs_mul(group, r, g_scalar, (point != NULL && p_scalar != NULL), points, scalars, ctx); 752 * ...
441 } 753 * points[2^(w-1)-1] = (2^(w-1)-1) * generator;
442 754 * points[2^(w-1)] = 2^blocksize * generator;
443 755 * points[2^(w-1)+1] = 3 * 2^blocksize * generator;
444int EC_GROUP_precompute_mult(EC_GROUP *group, BN_CTX *ctx) 756 * ...
757 * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator
758 * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator
759 * ...
760 * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator
761 * points[2^(w-1)*numblocks] = NULL
762 */
763int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
445 { 764 {
446 const EC_POINT *generator; 765 const EC_POINT *generator;
766 EC_POINT *tmp_point = NULL, *base = NULL, **var;
447 BN_CTX *new_ctx = NULL; 767 BN_CTX *new_ctx = NULL;
448 BIGNUM *order; 768 BIGNUM *order;
769 size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num;
770 EC_POINT **points = NULL;
771 EC_PRE_COMP *pre_comp;
449 int ret = 0; 772 int ret = 0;
450 773
774 /* if there is an old EC_PRE_COMP object, throw it away */
775 EC_EX_DATA_free_data(&group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
776
777 if ((pre_comp = ec_pre_comp_new(group)) == NULL)
778 return 0;
779
451 generator = EC_GROUP_get0_generator(group); 780 generator = EC_GROUP_get0_generator(group);
452 if (generator == NULL) 781 if (generator == NULL)
453 { 782 {
454 ECerr(EC_F_EC_GROUP_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); 783 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR);
455 return 0; 784 goto err;
456 } 785 }
457 786
458 if (ctx == NULL) 787 if (ctx == NULL)
459 { 788 {
460 ctx = new_ctx = BN_CTX_new(); 789 ctx = new_ctx = BN_CTX_new();
461 if (ctx == NULL) 790 if (ctx == NULL)
462 return 0; 791 goto err;
463 } 792 }
464 793
465 BN_CTX_start(ctx); 794 BN_CTX_start(ctx);
466 order = BN_CTX_get(ctx); 795 order = BN_CTX_get(ctx);
467 if (order == NULL) goto err; 796 if (order == NULL) goto err;
468 797
469 if (!EC_GROUP_get_order(group, order, ctx)) return 0; 798 if (!EC_GROUP_get_order(group, order, ctx)) goto err;
470 if (BN_is_zero(order)) 799 if (BN_is_zero(order))
471 { 800 {
472 ECerr(EC_F_EC_GROUP_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); 801 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER);
473 goto err; 802 goto err;
474 } 803 }
475 804
476 /* TODO */ 805 bits = BN_num_bits(order);
806 /* The following parameters mean we precompute (approximately)
807 * one point per bit.
808 *
809 * TBD: The combination 8, 4 is perfect for 160 bits; for other
810 * bit lengths, other parameter combinations might provide better
811 * efficiency.
812 */
813 blocksize = 8;
814 w = 4;
815 if (EC_window_bits_for_scalar_size(bits) > w)
816 {
817 /* let's not make the window too small ... */
818 w = EC_window_bits_for_scalar_size(bits);
819 }
820
821 numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks to use for wNAF splitting */
822
823 pre_points_per_block = 1u << (w - 1);
824 num = pre_points_per_block * numblocks; /* number of points to compute and store */
477 825
478 ret = 1; 826 points = OPENSSL_malloc(sizeof (EC_POINT*)*(num + 1));
827 if (!points)
828 {
829 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
830 goto err;
831 }
832
833 var = points;
834 var[num] = NULL; /* pivot */
835 for (i = 0; i < num; i++)
836 {
837 if ((var[i] = EC_POINT_new(group)) == NULL)
838 {
839 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
840 goto err;
841 }
842 }
843
844 if (!(tmp_point = EC_POINT_new(group)) || !(base = EC_POINT_new(group)))
845 {
846 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
847 goto err;
848 }
849
850 if (!EC_POINT_copy(base, generator))
851 goto err;
852
853 /* do the precomputation */
854 for (i = 0; i < numblocks; i++)
855 {
856 size_t j;
857
858 if (!EC_POINT_dbl(group, tmp_point, base, ctx))
859 goto err;
860
861 if (!EC_POINT_copy(*var++, base))
862 goto err;
863
864 for (j = 1; j < pre_points_per_block; j++, var++)
865 {
866 /* calculate odd multiples of the current base point */
867 if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx))
868 goto err;
869 }
870
871 if (i < numblocks - 1)
872 {
873 /* get the next base (multiply current one by 2^blocksize) */
874 size_t k;
875
876 if (blocksize <= 2)
877 {
878 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR);
879 goto err;
880 }
881
882 if (!EC_POINT_dbl(group, base, tmp_point, ctx))
883 goto err;
884 for (k = 2; k < blocksize; k++)
885 {
886 if (!EC_POINT_dbl(group,base,base,ctx))
887 goto err;
888 }
889 }
890 }
891
892 if (!EC_POINTs_make_affine(group, num, points, ctx))
893 goto err;
479 894
895 pre_comp->group = group;
896 pre_comp->blocksize = blocksize;
897 pre_comp->numblocks = numblocks;
898 pre_comp->w = w;
899 pre_comp->points = points;
900 points = NULL;
901 pre_comp->num = num;
902
903 if (!EC_EX_DATA_set_data(&group->extra_data, pre_comp,
904 ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free))
905 goto err;
906 pre_comp = NULL;
907
908 ret = 1;
480 err: 909 err:
481 BN_CTX_end(ctx); 910 if (ctx != NULL)
911 BN_CTX_end(ctx);
482 if (new_ctx != NULL) 912 if (new_ctx != NULL)
483 BN_CTX_free(new_ctx); 913 BN_CTX_free(new_ctx);
914 if (pre_comp)
915 ec_pre_comp_free(pre_comp);
916 if (points)
917 {
918 EC_POINT **p;
919
920 for (p = points; *p != NULL; p++)
921 EC_POINT_free(*p);
922 OPENSSL_free(points);
923 }
924 if (tmp_point)
925 EC_POINT_free(tmp_point);
926 if (base)
927 EC_POINT_free(base);
484 return ret; 928 return ret;
485 } 929 }
930
931
932int ec_wNAF_have_precompute_mult(const EC_GROUP *group)
933 {
934 if (EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free) != NULL)
935 return 1;
936 else
937 return 0;
938 }
generated by cgit v1.2.3-55-g6feb (git 2.39.1) at 2025-10-26 18:25:36 +0000