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d02b48c6 | 1 | /* crypto/bn/bn_mont.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
3 | * All rights reserved. |
4 | * | |
5 | * This package is an SSL implementation written | |
6 | * by Eric Young (eay@cryptsoft.com). | |
7 | * The implementation was written so as to conform with Netscapes SSL. | |
0f113f3e | 8 | * |
d02b48c6 RE |
9 | * This library is free for commercial and non-commercial use as long as |
10 | * the following conditions are aheared to. The following conditions | |
11 | * apply to all code found in this distribution, be it the RC4, RSA, | |
12 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation | |
13 | * included with this distribution is covered by the same copyright terms | |
14 | * except that the holder is Tim Hudson (tjh@cryptsoft.com). | |
0f113f3e | 15 | * |
d02b48c6 RE |
16 | * Copyright remains Eric Young's, and as such any Copyright notices in |
17 | * the code are not to be removed. | |
18 | * If this package is used in a product, Eric Young should be given attribution | |
19 | * as the author of the parts of the library used. | |
20 | * This can be in the form of a textual message at program startup or | |
21 | * in documentation (online or textual) provided with the package. | |
0f113f3e | 22 | * |
d02b48c6 RE |
23 | * Redistribution and use in source and binary forms, with or without |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
26 | * 1. Redistributions of source code must retain the copyright | |
27 | * notice, this list of conditions and the following disclaimer. | |
28 | * 2. Redistributions in binary form must reproduce the above copyright | |
29 | * notice, this list of conditions and the following disclaimer in the | |
30 | * documentation and/or other materials provided with the distribution. | |
31 | * 3. All advertising materials mentioning features or use of this software | |
32 | * must display the following acknowledgement: | |
33 | * "This product includes cryptographic software written by | |
34 | * Eric Young (eay@cryptsoft.com)" | |
35 | * The word 'cryptographic' can be left out if the rouines from the library | |
36 | * being used are not cryptographic related :-). | |
0f113f3e | 37 | * 4. If you include any Windows specific code (or a derivative thereof) from |
d02b48c6 RE |
38 | * the apps directory (application code) you must include an acknowledgement: |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
0f113f3e | 40 | * |
d02b48c6 RE |
41 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
42 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
43 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
44 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
45 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
46 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
47 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
48 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
49 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
50 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
51 | * SUCH DAMAGE. | |
0f113f3e | 52 | * |
d02b48c6 RE |
53 | * The licence and distribution terms for any publically available version or |
54 | * derivative of this code cannot be changed. i.e. this code cannot simply be | |
55 | * copied and put under another distribution licence | |
56 | * [including the GNU Public Licence.] | |
57 | */ | |
675f605d BM |
58 | /* ==================================================================== |
59 | * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved. | |
60 | * | |
61 | * Redistribution and use in source and binary forms, with or without | |
62 | * modification, are permitted provided that the following conditions | |
63 | * are met: | |
64 | * | |
65 | * 1. Redistributions of source code must retain the above copyright | |
0f113f3e | 66 | * notice, this list of conditions and the following disclaimer. |
675f605d BM |
67 | * |
68 | * 2. Redistributions in binary form must reproduce the above copyright | |
69 | * notice, this list of conditions and the following disclaimer in | |
70 | * the documentation and/or other materials provided with the | |
71 | * distribution. | |
72 | * | |
73 | * 3. All advertising materials mentioning features or use of this | |
74 | * software must display the following acknowledgment: | |
75 | * "This product includes software developed by the OpenSSL Project | |
76 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
77 | * | |
78 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
79 | * endorse or promote products derived from this software without | |
80 | * prior written permission. For written permission, please contact | |
81 | * openssl-core@openssl.org. | |
82 | * | |
83 | * 5. Products derived from this software may not be called "OpenSSL" | |
84 | * nor may "OpenSSL" appear in their names without prior written | |
85 | * permission of the OpenSSL Project. | |
86 | * | |
87 | * 6. Redistributions of any form whatsoever must retain the following | |
88 | * acknowledgment: | |
89 | * "This product includes software developed by the OpenSSL Project | |
90 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
91 | * | |
92 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
93 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
94 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
95 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
96 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
97 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
98 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
99 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
100 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
101 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
102 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
103 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
104 | * ==================================================================== | |
105 | * | |
106 | * This product includes cryptographic software written by Eric Young | |
107 | * (eay@cryptsoft.com). This product includes software written by Tim | |
108 | * Hudson (tjh@cryptsoft.com). | |
109 | * | |
110 | */ | |
d02b48c6 | 111 | |
1b3b0a54 | 112 | /* |
b99b1107 BM |
113 | * Details about Montgomery multiplication algorithms can be found at |
114 | * http://security.ece.orst.edu/publications.html, e.g. | |
115 | * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and | |
116 | * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf | |
1b3b0a54 RE |
117 | */ |
118 | ||
b39fc560 | 119 | #include "internal/cryptlib.h" |
d02b48c6 RE |
120 | #include "bn_lcl.h" |
121 | ||
0f113f3e | 122 | #define MONT_WORD /* use the faster word-based algorithm */ |
6535eb17 | 123 | |
9b4eab50 AP |
124 | #ifdef MONT_WORD |
125 | static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont); | |
126 | #endif | |
127 | ||
020fc820 | 128 | int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, |
0f113f3e MC |
129 | BN_MONT_CTX *mont, BN_CTX *ctx) |
130 | { | |
131 | BIGNUM *tmp; | |
132 | int ret = 0; | |
9b4eab50 | 133 | #if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD) |
0f113f3e MC |
134 | int num = mont->N.top; |
135 | ||
136 | if (num > 1 && a->top == num && b->top == num) { | |
137 | if (bn_wexpand(r, num) == NULL) | |
138 | return (0); | |
139 | if (bn_mul_mont(r->d, a->d, b->d, mont->N.d, mont->n0, num)) { | |
140 | r->neg = a->neg ^ b->neg; | |
141 | r->top = num; | |
142 | bn_correct_top(r); | |
143 | return (1); | |
144 | } | |
145 | } | |
e7382805 | 146 | #endif |
dfeab068 | 147 | |
0f113f3e MC |
148 | BN_CTX_start(ctx); |
149 | tmp = BN_CTX_get(ctx); | |
150 | if (tmp == NULL) | |
151 | goto err; | |
152 | ||
153 | bn_check_top(tmp); | |
154 | if (a == b) { | |
155 | if (!BN_sqr(tmp, a, ctx)) | |
156 | goto err; | |
157 | } else { | |
158 | if (!BN_mul(tmp, a, b, ctx)) | |
159 | goto err; | |
160 | } | |
161 | /* reduce from aRR to aR */ | |
9b4eab50 | 162 | #ifdef MONT_WORD |
0f113f3e MC |
163 | if (!BN_from_montgomery_word(r, tmp, mont)) |
164 | goto err; | |
9b4eab50 | 165 | #else |
0f113f3e MC |
166 | if (!BN_from_montgomery(r, tmp, mont, ctx)) |
167 | goto err; | |
9b4eab50 | 168 | #endif |
0f113f3e MC |
169 | bn_check_top(r); |
170 | ret = 1; | |
171 | err: | |
172 | BN_CTX_end(ctx); | |
173 | return (ret); | |
174 | } | |
d02b48c6 | 175 | |
6535eb17 | 176 | #ifdef MONT_WORD |
9b4eab50 | 177 | static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) |
0f113f3e MC |
178 | { |
179 | BIGNUM *n; | |
180 | BN_ULONG *ap, *np, *rp, n0, v, carry; | |
181 | int nl, max, i; | |
182 | ||
183 | n = &(mont->N); | |
184 | nl = n->top; | |
185 | if (nl == 0) { | |
186 | ret->top = 0; | |
187 | return (1); | |
188 | } | |
189 | ||
190 | max = (2 * nl); /* carry is stored separately */ | |
191 | if (bn_wexpand(r, max) == NULL) | |
192 | return (0); | |
193 | ||
194 | r->neg ^= n->neg; | |
195 | np = n->d; | |
196 | rp = r->d; | |
197 | ||
198 | /* clear the top words of T */ | |
9f040d6d RS |
199 | i = max - r->top; |
200 | if (i) | |
201 | memset(&rp[r->top], 0, sizeof(*rp) * i); | |
0f113f3e MC |
202 | |
203 | r->top = max; | |
204 | n0 = mont->n0[0]; | |
205 | ||
206 | for (carry = 0, i = 0; i < nl; i++, rp++) { | |
207 | v = bn_mul_add_words(rp, np, nl, (rp[0] * n0) & BN_MASK2); | |
208 | v = (v + carry + rp[nl]) & BN_MASK2; | |
209 | carry |= (v != rp[nl]); | |
210 | carry &= (v <= rp[nl]); | |
211 | rp[nl] = v; | |
212 | } | |
213 | ||
214 | if (bn_wexpand(ret, nl) == NULL) | |
215 | return (0); | |
216 | ret->top = nl; | |
217 | ret->neg = r->neg; | |
218 | ||
219 | rp = ret->d; | |
220 | ap = &(r->d[nl]); | |
221 | ||
222 | # define BRANCH_FREE 1 | |
223 | # if BRANCH_FREE | |
224 | { | |
225 | BN_ULONG *nrp; | |
226 | size_t m; | |
227 | ||
228 | v = bn_sub_words(rp, ap, np, nl) - carry; | |
229 | /* | |
230 | * if subtraction result is real, then trick unconditional memcpy | |
231 | * below to perform in-place "refresh" instead of actual copy. | |
232 | */ | |
233 | m = (0 - (size_t)v); | |
234 | nrp = | |
235 | (BN_ULONG *)(((PTR_SIZE_INT) rp & ~m) | ((PTR_SIZE_INT) ap & m)); | |
236 | ||
237 | for (i = 0, nl -= 4; i < nl; i += 4) { | |
238 | BN_ULONG t1, t2, t3, t4; | |
239 | ||
240 | t1 = nrp[i + 0]; | |
241 | t2 = nrp[i + 1]; | |
242 | t3 = nrp[i + 2]; | |
243 | ap[i + 0] = 0; | |
244 | t4 = nrp[i + 3]; | |
245 | ap[i + 1] = 0; | |
246 | rp[i + 0] = t1; | |
247 | ap[i + 2] = 0; | |
248 | rp[i + 1] = t2; | |
249 | ap[i + 3] = 0; | |
250 | rp[i + 2] = t3; | |
251 | rp[i + 3] = t4; | |
252 | } | |
253 | for (nl += 4; i < nl; i++) | |
254 | rp[i] = nrp[i], ap[i] = 0; | |
255 | } | |
256 | # else | |
257 | if (bn_sub_words(rp, ap, np, nl) - carry) | |
258 | memcpy(rp, ap, nl * sizeof(BN_ULONG)); | |
259 | # endif | |
260 | bn_correct_top(r); | |
261 | bn_correct_top(ret); | |
262 | bn_check_top(ret); | |
263 | ||
264 | return (1); | |
265 | } | |
266 | #endif /* MONT_WORD */ | |
9b4eab50 AP |
267 | |
268 | int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont, | |
0f113f3e MC |
269 | BN_CTX *ctx) |
270 | { | |
271 | int retn = 0; | |
9b4eab50 | 272 | #ifdef MONT_WORD |
0f113f3e MC |
273 | BIGNUM *t; |
274 | ||
275 | BN_CTX_start(ctx); | |
276 | if ((t = BN_CTX_get(ctx)) && BN_copy(t, a)) | |
277 | retn = BN_from_montgomery_word(ret, t, mont); | |
278 | BN_CTX_end(ctx); | |
279 | #else /* !MONT_WORD */ | |
280 | BIGNUM *t1, *t2; | |
281 | ||
282 | BN_CTX_start(ctx); | |
283 | t1 = BN_CTX_get(ctx); | |
284 | t2 = BN_CTX_get(ctx); | |
285 | if (t1 == NULL || t2 == NULL) | |
286 | goto err; | |
287 | ||
288 | if (!BN_copy(t1, a)) | |
289 | goto err; | |
290 | BN_mask_bits(t1, mont->ri); | |
291 | ||
292 | if (!BN_mul(t2, t1, &mont->Ni, ctx)) | |
293 | goto err; | |
294 | BN_mask_bits(t2, mont->ri); | |
295 | ||
296 | if (!BN_mul(t1, t2, &mont->N, ctx)) | |
297 | goto err; | |
298 | if (!BN_add(t2, a, t1)) | |
299 | goto err; | |
300 | if (!BN_rshift(ret, t2, mont->ri)) | |
301 | goto err; | |
302 | ||
303 | if (BN_ucmp(ret, &(mont->N)) >= 0) { | |
304 | if (!BN_usub(ret, ret, &(mont->N))) | |
305 | goto err; | |
306 | } | |
307 | retn = 1; | |
308 | bn_check_top(ret); | |
e93f9a32 | 309 | err: |
0f113f3e MC |
310 | BN_CTX_end(ctx); |
311 | #endif /* MONT_WORD */ | |
312 | return (retn); | |
313 | } | |
d02b48c6 | 314 | |
6b691a5c | 315 | BN_MONT_CTX *BN_MONT_CTX_new(void) |
0f113f3e MC |
316 | { |
317 | BN_MONT_CTX *ret; | |
d02b48c6 | 318 | |
b4faea50 | 319 | if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) |
0f113f3e | 320 | return (NULL); |
dfeab068 | 321 | |
0f113f3e MC |
322 | BN_MONT_CTX_init(ret); |
323 | ret->flags = BN_FLG_MALLOCED; | |
324 | return (ret); | |
325 | } | |
d02b48c6 | 326 | |
6b691a5c | 327 | void BN_MONT_CTX_init(BN_MONT_CTX *ctx) |
0f113f3e MC |
328 | { |
329 | ctx->ri = 0; | |
330 | BN_init(&(ctx->RR)); | |
331 | BN_init(&(ctx->N)); | |
332 | BN_init(&(ctx->Ni)); | |
333 | ctx->n0[0] = ctx->n0[1] = 0; | |
334 | ctx->flags = 0; | |
335 | } | |
dfeab068 | 336 | |
6b691a5c | 337 | void BN_MONT_CTX_free(BN_MONT_CTX *mont) |
0f113f3e MC |
338 | { |
339 | if (mont == NULL) | |
340 | return; | |
e03ddfae | 341 | |
1a586b39 LV |
342 | BN_clear_free(&(mont->RR)); |
343 | BN_clear_free(&(mont->N)); | |
344 | BN_clear_free(&(mont->Ni)); | |
0f113f3e MC |
345 | if (mont->flags & BN_FLG_MALLOCED) |
346 | OPENSSL_free(mont); | |
347 | } | |
d02b48c6 | 348 | |
84c15db5 | 349 | int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx) |
0f113f3e MC |
350 | { |
351 | int ret = 0; | |
352 | BIGNUM *Ri, *R; | |
353 | ||
6a009812 MC |
354 | if (BN_is_zero(mod)) |
355 | return 0; | |
356 | ||
0f113f3e MC |
357 | BN_CTX_start(ctx); |
358 | if ((Ri = BN_CTX_get(ctx)) == NULL) | |
359 | goto err; | |
360 | R = &(mont->RR); /* grab RR as a temp */ | |
361 | if (!BN_copy(&(mont->N), mod)) | |
362 | goto err; /* Set N */ | |
363 | mont->N.neg = 0; | |
dfeab068 | 364 | |
6535eb17 | 365 | #ifdef MONT_WORD |
0f113f3e MC |
366 | { |
367 | BIGNUM tmod; | |
368 | BN_ULONG buf[2]; | |
369 | ||
370 | BN_init(&tmod); | |
371 | tmod.d = buf; | |
372 | tmod.dmax = 2; | |
373 | tmod.neg = 0; | |
374 | ||
375 | mont->ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2; | |
376 | ||
377 | # if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32) | |
378 | /* | |
379 | * Only certain BN_BITS2<=32 platforms actually make use of n0[1], | |
380 | * and we could use the #else case (with a shorter R value) for the | |
381 | * others. However, currently only the assembler files do know which | |
382 | * is which. | |
383 | */ | |
384 | ||
385 | BN_zero(R); | |
386 | if (!(BN_set_bit(R, 2 * BN_BITS2))) | |
387 | goto err; | |
388 | ||
389 | tmod.top = 0; | |
390 | if ((buf[0] = mod->d[0])) | |
391 | tmod.top = 1; | |
392 | if ((buf[1] = mod->top > 1 ? mod->d[1] : 0)) | |
393 | tmod.top = 2; | |
394 | ||
395 | if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL) | |
396 | goto err; | |
397 | if (!BN_lshift(Ri, Ri, 2 * BN_BITS2)) | |
398 | goto err; /* R*Ri */ | |
399 | if (!BN_is_zero(Ri)) { | |
400 | if (!BN_sub_word(Ri, 1)) | |
401 | goto err; | |
402 | } else { /* if N mod word size == 1 */ | |
403 | ||
404 | if (bn_expand(Ri, (int)sizeof(BN_ULONG) * 2) == NULL) | |
405 | goto err; | |
406 | /* Ri-- (mod double word size) */ | |
407 | Ri->neg = 0; | |
408 | Ri->d[0] = BN_MASK2; | |
409 | Ri->d[1] = BN_MASK2; | |
410 | Ri->top = 2; | |
411 | } | |
412 | if (!BN_div(Ri, NULL, Ri, &tmod, ctx)) | |
413 | goto err; | |
414 | /* | |
415 | * Ni = (R*Ri-1)/N, keep only couple of least significant words: | |
416 | */ | |
417 | mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; | |
418 | mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0; | |
419 | # else | |
420 | BN_zero(R); | |
421 | if (!(BN_set_bit(R, BN_BITS2))) | |
422 | goto err; /* R */ | |
423 | ||
424 | buf[0] = mod->d[0]; /* tmod = N mod word size */ | |
425 | buf[1] = 0; | |
426 | tmod.top = buf[0] != 0 ? 1 : 0; | |
427 | /* Ri = R^-1 mod N */ | |
428 | if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL) | |
429 | goto err; | |
430 | if (!BN_lshift(Ri, Ri, BN_BITS2)) | |
431 | goto err; /* R*Ri */ | |
432 | if (!BN_is_zero(Ri)) { | |
433 | if (!BN_sub_word(Ri, 1)) | |
434 | goto err; | |
435 | } else { /* if N mod word size == 1 */ | |
436 | ||
437 | if (!BN_set_word(Ri, BN_MASK2)) | |
438 | goto err; /* Ri-- (mod word size) */ | |
439 | } | |
440 | if (!BN_div(Ri, NULL, Ri, &tmod, ctx)) | |
441 | goto err; | |
442 | /* | |
443 | * Ni = (R*Ri-1)/N, keep only least significant word: | |
444 | */ | |
445 | mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; | |
446 | mont->n0[1] = 0; | |
447 | # endif | |
448 | } | |
449 | #else /* !MONT_WORD */ | |
450 | { /* bignum version */ | |
451 | mont->ri = BN_num_bits(&mont->N); | |
452 | BN_zero(R); | |
453 | if (!BN_set_bit(R, mont->ri)) | |
454 | goto err; /* R = 2^ri */ | |
455 | /* Ri = R^-1 mod N */ | |
456 | if ((BN_mod_inverse(Ri, R, &mont->N, ctx)) == NULL) | |
457 | goto err; | |
458 | if (!BN_lshift(Ri, Ri, mont->ri)) | |
459 | goto err; /* R*Ri */ | |
460 | if (!BN_sub_word(Ri, 1)) | |
461 | goto err; | |
462 | /* | |
463 | * Ni = (R*Ri-1) / N | |
464 | */ | |
465 | if (!BN_div(&(mont->Ni), NULL, Ri, &mont->N, ctx)) | |
466 | goto err; | |
467 | } | |
d02b48c6 RE |
468 | #endif |
469 | ||
0f113f3e MC |
470 | /* setup RR for conversions */ |
471 | BN_zero(&(mont->RR)); | |
472 | if (!BN_set_bit(&(mont->RR), mont->ri * 2)) | |
473 | goto err; | |
474 | if (!BN_mod(&(mont->RR), &(mont->RR), &(mont->N), ctx)) | |
475 | goto err; | |
d02b48c6 | 476 | |
0f113f3e MC |
477 | ret = 1; |
478 | err: | |
479 | BN_CTX_end(ctx); | |
480 | return ret; | |
481 | } | |
d02b48c6 | 482 | |
6b691a5c | 483 | BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from) |
0f113f3e MC |
484 | { |
485 | if (to == from) | |
486 | return (to); | |
487 | ||
488 | if (!BN_copy(&(to->RR), &(from->RR))) | |
489 | return NULL; | |
490 | if (!BN_copy(&(to->N), &(from->N))) | |
491 | return NULL; | |
492 | if (!BN_copy(&(to->Ni), &(from->Ni))) | |
493 | return NULL; | |
494 | to->ri = from->ri; | |
495 | to->n0[0] = from->n0[0]; | |
496 | to->n0[1] = from->n0[1]; | |
497 | return (to); | |
498 | } | |
dfeab068 | 499 | |
6ec8e63a | 500 | BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock, |
0f113f3e MC |
501 | const BIGNUM *mod, BN_CTX *ctx) |
502 | { | |
503 | BN_MONT_CTX *ret; | |
504 | ||
505 | CRYPTO_r_lock(lock); | |
506 | ret = *pmont; | |
507 | CRYPTO_r_unlock(lock); | |
508 | if (ret) | |
509 | return ret; | |
510 | ||
511 | /* | |
512 | * We don't want to serialise globally while doing our lazy-init math in | |
513 | * BN_MONT_CTX_set. That punishes threads that are doing independent | |
514 | * things. Instead, punish the case where more than one thread tries to | |
515 | * lazy-init the same 'pmont', by having each do the lazy-init math work | |
516 | * independently and only use the one from the thread that wins the race | |
517 | * (the losers throw away the work they've done). | |
518 | */ | |
519 | ret = BN_MONT_CTX_new(); | |
520 | if (!ret) | |
521 | return NULL; | |
522 | if (!BN_MONT_CTX_set(ret, mod, ctx)) { | |
523 | BN_MONT_CTX_free(ret); | |
524 | return NULL; | |
525 | } | |
526 | ||
527 | /* The locked compare-and-set, after the local work is done. */ | |
528 | CRYPTO_w_lock(lock); | |
529 | if (*pmont) { | |
530 | BN_MONT_CTX_free(ret); | |
531 | ret = *pmont; | |
532 | } else | |
533 | *pmont = ret; | |
534 | CRYPTO_w_unlock(lock); | |
535 | return ret; | |
536 | } |