155714Skris/* crypto/bn/bn_prime.c */ 255714Skris/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 355714Skris * All rights reserved. 455714Skris * 555714Skris * This package is an SSL implementation written 655714Skris * by Eric Young (eay@cryptsoft.com). 755714Skris * The implementation was written so as to conform with Netscapes SSL. 8296465Sdelphij * 955714Skris * This library is free for commercial and non-commercial use as long as 1055714Skris * the following conditions are aheared to. The following conditions 1155714Skris * apply to all code found in this distribution, be it the RC4, RSA, 1255714Skris * lhash, DES, etc., code; not just the SSL code. The SSL documentation 1355714Skris * included with this distribution is covered by the same copyright terms 1455714Skris * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15296465Sdelphij * 1655714Skris * Copyright remains Eric Young's, and as such any Copyright notices in 1755714Skris * the code are not to be removed. 1855714Skris * If this package is used in a product, Eric Young should be given attribution 1955714Skris * as the author of the parts of the library used. 2055714Skris * This can be in the form of a textual message at program startup or 2155714Skris * in documentation (online or textual) provided with the package. 22296465Sdelphij * 2355714Skris * Redistribution and use in source and binary forms, with or without 2455714Skris * modification, are permitted provided that the following conditions 2555714Skris * are met: 2655714Skris * 1. Redistributions of source code must retain the copyright 2755714Skris * notice, this list of conditions and the following disclaimer. 2855714Skris * 2. Redistributions in binary form must reproduce the above copyright 2955714Skris * notice, this list of conditions and the following disclaimer in the 3055714Skris * documentation and/or other materials provided with the distribution. 3155714Skris * 3. All advertising materials mentioning features or use of this software 3255714Skris * must display the following acknowledgement: 3355714Skris * "This product includes cryptographic software written by 3455714Skris * Eric Young (eay@cryptsoft.com)" 3555714Skris * The word 'cryptographic' can be left out if the rouines from the library 3655714Skris * being used are not cryptographic related :-). 37296465Sdelphij * 4. If you include any Windows specific code (or a derivative thereof) from 3855714Skris * the apps directory (application code) you must include an acknowledgement: 3955714Skris * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40296465Sdelphij * 4155714Skris * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 4255714Skris * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 4355714Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 4455714Skris * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 4555714Skris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 4655714Skris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 4755714Skris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 4855714Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 4955714Skris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 5055714Skris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 5155714Skris * SUCH DAMAGE. 52296465Sdelphij * 5355714Skris * The licence and distribution terms for any publically available version or 5455714Skris * derivative of this code cannot be changed. i.e. this code cannot simply be 5555714Skris * copied and put under another distribution licence 5655714Skris * [including the GNU Public Licence.] 5755714Skris */ 5859191Skris/* ==================================================================== 59109998Smarkm * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved. 6059191Skris * 6159191Skris * Redistribution and use in source and binary forms, with or without 6259191Skris * modification, are permitted provided that the following conditions 6359191Skris * are met: 6459191Skris * 6559191Skris * 1. Redistributions of source code must retain the above copyright 66296465Sdelphij * notice, this list of conditions and the following disclaimer. 6759191Skris * 6859191Skris * 2. Redistributions in binary form must reproduce the above copyright 6959191Skris * notice, this list of conditions and the following disclaimer in 7059191Skris * the documentation and/or other materials provided with the 7159191Skris * distribution. 7259191Skris * 7359191Skris * 3. All advertising materials mentioning features or use of this 7459191Skris * software must display the following acknowledgment: 7559191Skris * "This product includes software developed by the OpenSSL Project 7659191Skris * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 7759191Skris * 7859191Skris * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 7959191Skris * endorse or promote products derived from this software without 8059191Skris * prior written permission. For written permission, please contact 8159191Skris * openssl-core@openssl.org. 8259191Skris * 8359191Skris * 5. Products derived from this software may not be called "OpenSSL" 8459191Skris * nor may "OpenSSL" appear in their names without prior written 8559191Skris * permission of the OpenSSL Project. 8659191Skris * 8759191Skris * 6. Redistributions of any form whatsoever must retain the following 8859191Skris * acknowledgment: 8959191Skris * "This product includes software developed by the OpenSSL Project 9059191Skris * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 9159191Skris * 9259191Skris * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 9359191Skris * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 9459191Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 9559191Skris * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 9659191Skris * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 9759191Skris * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 9859191Skris * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 9959191Skris * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 10059191Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 10159191Skris * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 10259191Skris * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 10359191Skris * OF THE POSSIBILITY OF SUCH DAMAGE. 10459191Skris * ==================================================================== 10559191Skris * 10659191Skris * This product includes cryptographic software written by Eric Young 10759191Skris * (eay@cryptsoft.com). This product includes software written by Tim 10859191Skris * Hudson (tjh@cryptsoft.com). 10959191Skris * 11059191Skris */ 11155714Skris 11255714Skris#include <stdio.h> 11355714Skris#include <time.h> 11455714Skris#include "cryptlib.h" 11555714Skris#include "bn_lcl.h" 11655714Skris#include <openssl/rand.h> 11755714Skris 118296465Sdelphij/* 119296465Sdelphij * NB: these functions have been "upgraded", the deprecated versions (which 120296465Sdelphij * are compatibility wrappers using these functions) are in bn_depr.c. - 121296465Sdelphij * Geoff 122160814Ssimon */ 123160814Ssimon 124296465Sdelphij/* 125296465Sdelphij * The quick sieve algorithm approach to weeding out primes is Philip 126296465Sdelphij * Zimmermann's, as implemented in PGP. I have had a read of his comments 127296465Sdelphij * and implemented my own version. 12855714Skris */ 12955714Skris#include "bn_prime.h" 13055714Skris 13159191Skrisstatic int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1, 132296465Sdelphij const BIGNUM *a1_odd, int k, BN_CTX *ctx, 133296465Sdelphij BN_MONT_CTX *mont); 13455714Skrisstatic int probable_prime(BIGNUM *rnd, int bits); 13555714Skrisstatic int probable_prime_dh(BIGNUM *rnd, int bits, 136296465Sdelphij const BIGNUM *add, const BIGNUM *rem, 137296465Sdelphij BN_CTX *ctx); 138296465Sdelphijstatic int probable_prime_dh_safe(BIGNUM *rnd, int bits, const BIGNUM *add, 139296465Sdelphij const BIGNUM *rem, BN_CTX *ctx); 14059191Skris 141160814Ssimonint BN_GENCB_call(BN_GENCB *cb, int a, int b) 142296465Sdelphij{ 143296465Sdelphij /* No callback means continue */ 144296465Sdelphij if (!cb) 145296465Sdelphij return 1; 146296465Sdelphij switch (cb->ver) { 147296465Sdelphij case 1: 148296465Sdelphij /* Deprecated-style callbacks */ 149296465Sdelphij if (!cb->cb.cb_1) 150296465Sdelphij return 1; 151296465Sdelphij cb->cb.cb_1(a, b, cb->arg); 152296465Sdelphij return 1; 153296465Sdelphij case 2: 154296465Sdelphij /* New-style callbacks */ 155296465Sdelphij return cb->cb.cb_2(a, b, cb); 156296465Sdelphij default: 157296465Sdelphij break; 158296465Sdelphij } 159296465Sdelphij /* Unrecognised callback type */ 160296465Sdelphij return 0; 161296465Sdelphij} 162160814Ssimon 163160814Ssimonint BN_generate_prime_ex(BIGNUM *ret, int bits, int safe, 164296465Sdelphij const BIGNUM *add, const BIGNUM *rem, BN_GENCB *cb) 165296465Sdelphij{ 166296465Sdelphij BIGNUM *t; 167296465Sdelphij int found = 0; 168296465Sdelphij int i, j, c1 = 0; 169296465Sdelphij BN_CTX *ctx; 170296465Sdelphij int checks = BN_prime_checks_for_size(bits); 17155714Skris 172296465Sdelphij ctx = BN_CTX_new(); 173296465Sdelphij if (ctx == NULL) 174296465Sdelphij goto err; 175296465Sdelphij BN_CTX_start(ctx); 176296465Sdelphij t = BN_CTX_get(ctx); 177296465Sdelphij if (!t) 178296465Sdelphij goto err; 179296465Sdelphij loop: 180296465Sdelphij /* make a random number and set the top and bottom bits */ 181296465Sdelphij if (add == NULL) { 182296465Sdelphij if (!probable_prime(ret, bits)) 183296465Sdelphij goto err; 184296465Sdelphij } else { 185296465Sdelphij if (safe) { 186296465Sdelphij if (!probable_prime_dh_safe(ret, bits, add, rem, ctx)) 187296465Sdelphij goto err; 188296465Sdelphij } else { 189296465Sdelphij if (!probable_prime_dh(ret, bits, add, rem, ctx)) 190296465Sdelphij goto err; 191296465Sdelphij } 192296465Sdelphij } 193296465Sdelphij /* if (BN_mod_word(ret,(BN_ULONG)3) == 1) goto loop; */ 194296465Sdelphij if (!BN_GENCB_call(cb, 0, c1++)) 195296465Sdelphij /* aborted */ 196296465Sdelphij goto err; 19755714Skris 198296465Sdelphij if (!safe) { 199296465Sdelphij i = BN_is_prime_fasttest_ex(ret, checks, ctx, 0, cb); 200296465Sdelphij if (i == -1) 201296465Sdelphij goto err; 202296465Sdelphij if (i == 0) 203296465Sdelphij goto loop; 204296465Sdelphij } else { 205296465Sdelphij /* 206296465Sdelphij * for "safe prime" generation, check that (p-1)/2 is prime. Since a 207296465Sdelphij * prime is odd, We just need to divide by 2 208296465Sdelphij */ 209296465Sdelphij if (!BN_rshift1(t, ret)) 210296465Sdelphij goto err; 21155714Skris 212296465Sdelphij for (i = 0; i < checks; i++) { 213296465Sdelphij j = BN_is_prime_fasttest_ex(ret, 1, ctx, 0, cb); 214296465Sdelphij if (j == -1) 215296465Sdelphij goto err; 216296465Sdelphij if (j == 0) 217296465Sdelphij goto loop; 21855714Skris 219296465Sdelphij j = BN_is_prime_fasttest_ex(t, 1, ctx, 0, cb); 220296465Sdelphij if (j == -1) 221296465Sdelphij goto err; 222296465Sdelphij if (j == 0) 223296465Sdelphij goto loop; 22455714Skris 225296465Sdelphij if (!BN_GENCB_call(cb, 2, c1 - 1)) 226296465Sdelphij goto err; 227296465Sdelphij /* We have a safe prime test pass */ 228296465Sdelphij } 229296465Sdelphij } 230296465Sdelphij /* we have a prime :-) */ 231296465Sdelphij found = 1; 232296465Sdelphij err: 233296465Sdelphij if (ctx != NULL) { 234296465Sdelphij BN_CTX_end(ctx); 235296465Sdelphij BN_CTX_free(ctx); 236296465Sdelphij } 237296465Sdelphij bn_check_top(ret); 238296465Sdelphij return found; 239296465Sdelphij} 24055714Skris 241296465Sdelphijint BN_is_prime_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, 242296465Sdelphij BN_GENCB *cb) 243296465Sdelphij{ 244296465Sdelphij return BN_is_prime_fasttest_ex(a, checks, ctx_passed, 0, cb); 245296465Sdelphij} 24655714Skris 247160814Ssimonint BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, 248296465Sdelphij int do_trial_division, BN_GENCB *cb) 249296465Sdelphij{ 250296465Sdelphij int i, j, ret = -1; 251296465Sdelphij int k; 252296465Sdelphij BN_CTX *ctx = NULL; 253296465Sdelphij BIGNUM *A1, *A1_odd, *check; /* taken from ctx */ 254296465Sdelphij BN_MONT_CTX *mont = NULL; 255296465Sdelphij const BIGNUM *A = NULL; 25659191Skris 257296465Sdelphij if (BN_cmp(a, BN_value_one()) <= 0) 258296465Sdelphij return 0; 25959191Skris 260296465Sdelphij if (checks == BN_prime_checks) 261296465Sdelphij checks = BN_prime_checks_for_size(BN_num_bits(a)); 26259191Skris 263296465Sdelphij /* first look for small factors */ 264296465Sdelphij if (!BN_is_odd(a)) 265296465Sdelphij /* a is even => a is prime if and only if a == 2 */ 266296465Sdelphij return BN_is_word(a, 2); 267296465Sdelphij if (do_trial_division) { 268296465Sdelphij for (i = 1; i < NUMPRIMES; i++) 269296465Sdelphij if (BN_mod_word(a, primes[i]) == 0) 270296465Sdelphij return 0; 271296465Sdelphij if (!BN_GENCB_call(cb, 1, -1)) 272296465Sdelphij goto err; 273296465Sdelphij } 27455714Skris 275296465Sdelphij if (ctx_passed != NULL) 276296465Sdelphij ctx = ctx_passed; 277296465Sdelphij else if ((ctx = BN_CTX_new()) == NULL) 278296465Sdelphij goto err; 279296465Sdelphij BN_CTX_start(ctx); 28055714Skris 281296465Sdelphij /* A := abs(a) */ 282296465Sdelphij if (a->neg) { 283296465Sdelphij BIGNUM *t; 284296465Sdelphij if ((t = BN_CTX_get(ctx)) == NULL) 285296465Sdelphij goto err; 286296465Sdelphij BN_copy(t, a); 287296465Sdelphij t->neg = 0; 288296465Sdelphij A = t; 289296465Sdelphij } else 290296465Sdelphij A = a; 291296465Sdelphij A1 = BN_CTX_get(ctx); 292296465Sdelphij A1_odd = BN_CTX_get(ctx); 293296465Sdelphij check = BN_CTX_get(ctx); 294296465Sdelphij if (check == NULL) 295296465Sdelphij goto err; 29655714Skris 297296465Sdelphij /* compute A1 := A - 1 */ 298296465Sdelphij if (!BN_copy(A1, A)) 299296465Sdelphij goto err; 300296465Sdelphij if (!BN_sub_word(A1, 1)) 301296465Sdelphij goto err; 302296465Sdelphij if (BN_is_zero(A1)) { 303296465Sdelphij ret = 0; 304296465Sdelphij goto err; 305296465Sdelphij } 30655714Skris 307296465Sdelphij /* write A1 as A1_odd * 2^k */ 308296465Sdelphij k = 1; 309296465Sdelphij while (!BN_is_bit_set(A1, k)) 310296465Sdelphij k++; 311296465Sdelphij if (!BN_rshift(A1_odd, A1, k)) 312296465Sdelphij goto err; 31359191Skris 314296465Sdelphij /* Montgomery setup for computations mod A */ 315296465Sdelphij mont = BN_MONT_CTX_new(); 316296465Sdelphij if (mont == NULL) 317296465Sdelphij goto err; 318296465Sdelphij if (!BN_MONT_CTX_set(mont, A, ctx)) 319296465Sdelphij goto err; 32059191Skris 321296465Sdelphij for (i = 0; i < checks; i++) { 322296465Sdelphij if (!BN_pseudo_rand_range(check, A1)) 323296465Sdelphij goto err; 324296465Sdelphij if (!BN_add_word(check, 1)) 325296465Sdelphij goto err; 326296465Sdelphij /* now 1 <= check < A */ 32755714Skris 328296465Sdelphij j = witness(check, A, A1, A1_odd, k, ctx, mont); 329296465Sdelphij if (j == -1) 330296465Sdelphij goto err; 331296465Sdelphij if (j) { 332296465Sdelphij ret = 0; 333296465Sdelphij goto err; 334296465Sdelphij } 335296465Sdelphij if (!BN_GENCB_call(cb, 1, i)) 336296465Sdelphij goto err; 337296465Sdelphij } 338296465Sdelphij ret = 1; 339296465Sdelphij err: 340296465Sdelphij if (ctx != NULL) { 341296465Sdelphij BN_CTX_end(ctx); 342296465Sdelphij if (ctx_passed == NULL) 343296465Sdelphij BN_CTX_free(ctx); 344296465Sdelphij } 345296465Sdelphij if (mont != NULL) 346296465Sdelphij BN_MONT_CTX_free(mont); 347296465Sdelphij 348296465Sdelphij return (ret); 349296465Sdelphij} 350296465Sdelphij 35159191Skrisstatic int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1, 352296465Sdelphij const BIGNUM *a1_odd, int k, BN_CTX *ctx, 353296465Sdelphij BN_MONT_CTX *mont) 354296465Sdelphij{ 355296465Sdelphij if (!BN_mod_exp_mont(w, w, a1_odd, a, ctx, mont)) /* w := w^a1_odd mod a */ 356296465Sdelphij return -1; 357296465Sdelphij if (BN_is_one(w)) 358296465Sdelphij return 0; /* probably prime */ 359296465Sdelphij if (BN_cmp(w, a1) == 0) 360296465Sdelphij return 0; /* w == -1 (mod a), 'a' is probably prime */ 361296465Sdelphij while (--k) { 362296465Sdelphij if (!BN_mod_mul(w, w, w, a, ctx)) /* w := w^2 mod a */ 363296465Sdelphij return -1; 364296465Sdelphij if (BN_is_one(w)) 365296465Sdelphij return 1; /* 'a' is composite, otherwise a previous 'w' 366296465Sdelphij * would have been == -1 (mod 'a') */ 367296465Sdelphij if (BN_cmp(w, a1) == 0) 368296465Sdelphij return 0; /* w == -1 (mod a), 'a' is probably prime */ 369296465Sdelphij } 370296465Sdelphij /* 371296465Sdelphij * If we get here, 'w' is the (a-1)/2-th power of the original 'w', and 372296465Sdelphij * it is neither -1 nor +1 -- so 'a' cannot be prime 373296465Sdelphij */ 374296465Sdelphij bn_check_top(w); 375296465Sdelphij return 1; 376296465Sdelphij} 37755714Skris 37855714Skrisstatic int probable_prime(BIGNUM *rnd, int bits) 379296465Sdelphij{ 380296465Sdelphij int i; 381296465Sdelphij prime_t mods[NUMPRIMES]; 382296465Sdelphij BN_ULONG delta, maxdelta; 38355714Skris 384296465Sdelphij again: 385296465Sdelphij if (!BN_rand(rnd, bits, 1, 1)) 386296465Sdelphij return (0); 387296465Sdelphij /* we now have a random number 'rand' to test. */ 388296465Sdelphij for (i = 1; i < NUMPRIMES; i++) 389296465Sdelphij mods[i] = (prime_t) BN_mod_word(rnd, (BN_ULONG)primes[i]); 390296465Sdelphij maxdelta = BN_MASK2 - primes[NUMPRIMES - 1]; 391296465Sdelphij delta = 0; 392296465Sdelphij loop:for (i = 1; i < NUMPRIMES; i++) { 393296465Sdelphij /* 394296465Sdelphij * check that rnd is not a prime and also that gcd(rnd-1,primes) == 1 395296465Sdelphij * (except for 2) 396296465Sdelphij */ 397296465Sdelphij if (((mods[i] + delta) % primes[i]) <= 1) { 398296465Sdelphij delta += 2; 399296465Sdelphij if (delta > maxdelta) 400296465Sdelphij goto again; 401296465Sdelphij goto loop; 402296465Sdelphij } 403296465Sdelphij } 404296465Sdelphij if (!BN_add_word(rnd, delta)) 405296465Sdelphij return (0); 406296465Sdelphij bn_check_top(rnd); 407296465Sdelphij return (1); 408296465Sdelphij} 40955714Skris 410109998Smarkmstatic int probable_prime_dh(BIGNUM *rnd, int bits, 411296465Sdelphij const BIGNUM *add, const BIGNUM *rem, 412296465Sdelphij BN_CTX *ctx) 413296465Sdelphij{ 414296465Sdelphij int i, ret = 0; 415296465Sdelphij BIGNUM *t1; 41655714Skris 417296465Sdelphij BN_CTX_start(ctx); 418296465Sdelphij if ((t1 = BN_CTX_get(ctx)) == NULL) 419296465Sdelphij goto err; 42055714Skris 421296465Sdelphij if (!BN_rand(rnd, bits, 0, 1)) 422296465Sdelphij goto err; 42355714Skris 424296465Sdelphij /* we need ((rnd-rem) % add) == 0 */ 42555714Skris 426296465Sdelphij if (!BN_mod(t1, rnd, add, ctx)) 427296465Sdelphij goto err; 428296465Sdelphij if (!BN_sub(rnd, rnd, t1)) 429296465Sdelphij goto err; 430296465Sdelphij if (rem == NULL) { 431296465Sdelphij if (!BN_add_word(rnd, 1)) 432296465Sdelphij goto err; 433296465Sdelphij } else { 434296465Sdelphij if (!BN_add(rnd, rnd, rem)) 435296465Sdelphij goto err; 436296465Sdelphij } 43755714Skris 438296465Sdelphij /* we now have a random number 'rand' to test. */ 43955714Skris 440296465Sdelphij loop:for (i = 1; i < NUMPRIMES; i++) { 441296465Sdelphij /* check that rnd is a prime */ 442296465Sdelphij if (BN_mod_word(rnd, (BN_ULONG)primes[i]) <= 1) { 443296465Sdelphij if (!BN_add(rnd, rnd, add)) 444296465Sdelphij goto err; 445296465Sdelphij goto loop; 446296465Sdelphij } 447296465Sdelphij } 448296465Sdelphij ret = 1; 449296465Sdelphij err: 450296465Sdelphij BN_CTX_end(ctx); 451296465Sdelphij bn_check_top(rnd); 452296465Sdelphij return (ret); 453296465Sdelphij} 45455714Skris 455109998Smarkmstatic int probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd, 456296465Sdelphij const BIGNUM *rem, BN_CTX *ctx) 457296465Sdelphij{ 458296465Sdelphij int i, ret = 0; 459296465Sdelphij BIGNUM *t1, *qadd, *q; 46055714Skris 461296465Sdelphij bits--; 462296465Sdelphij BN_CTX_start(ctx); 463296465Sdelphij t1 = BN_CTX_get(ctx); 464296465Sdelphij q = BN_CTX_get(ctx); 465296465Sdelphij qadd = BN_CTX_get(ctx); 466296465Sdelphij if (qadd == NULL) 467296465Sdelphij goto err; 46855714Skris 469296465Sdelphij if (!BN_rshift1(qadd, padd)) 470296465Sdelphij goto err; 47155714Skris 472296465Sdelphij if (!BN_rand(q, bits, 0, 1)) 473296465Sdelphij goto err; 47455714Skris 475296465Sdelphij /* we need ((rnd-rem) % add) == 0 */ 476296465Sdelphij if (!BN_mod(t1, q, qadd, ctx)) 477296465Sdelphij goto err; 478296465Sdelphij if (!BN_sub(q, q, t1)) 479296465Sdelphij goto err; 480296465Sdelphij if (rem == NULL) { 481296465Sdelphij if (!BN_add_word(q, 1)) 482296465Sdelphij goto err; 483296465Sdelphij } else { 484296465Sdelphij if (!BN_rshift1(t1, rem)) 485296465Sdelphij goto err; 486296465Sdelphij if (!BN_add(q, q, t1)) 487296465Sdelphij goto err; 488296465Sdelphij } 48955714Skris 490296465Sdelphij /* we now have a random number 'rand' to test. */ 491296465Sdelphij if (!BN_lshift1(p, q)) 492296465Sdelphij goto err; 493296465Sdelphij if (!BN_add_word(p, 1)) 494296465Sdelphij goto err; 495296465Sdelphij 496296465Sdelphij loop:for (i = 1; i < NUMPRIMES; i++) { 497296465Sdelphij /* check that p and q are prime */ 498296465Sdelphij /* 499296465Sdelphij * check that for p and q gcd(p-1,primes) == 1 (except for 2) 500296465Sdelphij */ 501296465Sdelphij if ((BN_mod_word(p, (BN_ULONG)primes[i]) == 0) || 502296465Sdelphij (BN_mod_word(q, (BN_ULONG)primes[i]) == 0)) { 503296465Sdelphij if (!BN_add(p, p, padd)) 504296465Sdelphij goto err; 505296465Sdelphij if (!BN_add(q, q, qadd)) 506296465Sdelphij goto err; 507296465Sdelphij goto loop; 508296465Sdelphij } 509296465Sdelphij } 510296465Sdelphij ret = 1; 511296465Sdelphij err: 512296465Sdelphij BN_CTX_end(ctx); 513296465Sdelphij bn_check_top(p); 514296465Sdelphij return (ret); 515296465Sdelphij} 516