1/* $OpenBSD: bn_rand.c,v 1.30 2024/03/16 20:42:33 tb Exp $ */ 2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 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. 8 * 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). 15 * 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. 22 * 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 :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40 * 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. 52 * 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 */ 58/* ==================================================================== 59 * Copyright (c) 1998-2001 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 66 * notice, this list of conditions and the following disclaimer. 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 */ 111 112#include <limits.h> 113#include <stdio.h> 114#include <stdlib.h> 115#include <string.h> 116#include <time.h> 117 118#include <openssl/err.h> 119 120#include "bn_local.h" 121 122static int 123bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) 124{ 125 unsigned char *buf = NULL; 126 int ret = 0, bit, bytes, mask; 127 128 if (rnd == NULL) { 129 BNerror(ERR_R_PASSED_NULL_PARAMETER); 130 return (0); 131 } 132 133 if (bits < 0 || (bits == 1 && top > 0)) { 134 BNerror(BN_R_BITS_TOO_SMALL); 135 return (0); 136 } 137 if (bits > INT_MAX - 7) { 138 BNerror(BN_R_BIGNUM_TOO_LONG); 139 return (0); 140 } 141 142 if (bits == 0) { 143 BN_zero(rnd); 144 return (1); 145 } 146 147 bytes = (bits + 7) / 8; 148 bit = (bits - 1) % 8; 149 mask = 0xff << (bit + 1); 150 151 buf = malloc(bytes); 152 if (buf == NULL) { 153 BNerror(ERR_R_MALLOC_FAILURE); 154 goto err; 155 } 156 157 /* make a random number and set the top and bottom bits */ 158 arc4random_buf(buf, bytes); 159 160#if 1 161 if (pseudorand == 2) { 162 /* generate patterns that are more likely to trigger BN 163 library bugs */ 164 int i; 165 unsigned char c; 166 167 for (i = 0; i < bytes; i++) { 168 arc4random_buf(&c, 1); 169 if (c >= 128 && i > 0) 170 buf[i] = buf[i - 1]; 171 else if (c < 42) 172 buf[i] = 0; 173 else if (c < 84) 174 buf[i] = 255; 175 } 176 } 177#endif 178 179 if (top > 0) { 180 if (bit == 0) { 181 buf[0] = 1; 182 buf[1] |= 0x80; 183 } else { 184 buf[0] |= (3 << (bit - 1)); 185 } 186 } 187 if (top == 0) 188 buf[0] |= (1 << bit); 189 buf[0] &= ~mask; 190 if (bottom) /* set bottom bit if requested */ 191 buf[bytes - 1] |= 1; 192 if (BN_bin2bn(buf, bytes, rnd) == NULL) 193 goto err; 194 ret = 1; 195 196err: 197 freezero(buf, bytes); 198 return (ret); 199} 200 201int 202BN_rand(BIGNUM *rnd, int bits, int top, int bottom) 203{ 204 return bnrand(0, rnd, bits, top, bottom); 205} 206LCRYPTO_ALIAS(BN_rand); 207 208int 209BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) 210{ 211 return bnrand(1, rnd, bits, top, bottom); 212} 213LCRYPTO_ALIAS(BN_pseudo_rand); 214 215#if 1 216int 217BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) 218{ 219 return bnrand(2, rnd, bits, top, bottom); 220} 221#endif 222 223 224/* random number r: 0 <= r < range */ 225static int 226bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) 227{ 228 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; 229 int n; 230 int count = 100; 231 232 if (range->neg || BN_is_zero(range)) { 233 BNerror(BN_R_INVALID_RANGE); 234 return 0; 235 } 236 237 n = BN_num_bits(range); /* n > 0 */ 238 239 /* BN_is_bit_set(range, n - 1) always holds */ 240 241 if (n == 1) 242 BN_zero(r); 243 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) { 244 /* range = 100..._2, 245 * so 3*range (= 11..._2) is exactly one bit longer than range */ 246 do { 247 if (!bn_rand(r, n + 1, -1, 0)) 248 return 0; 249 /* If r < 3*range, use r := r MOD range 250 * (which is either r, r - range, or r - 2*range). 251 * Otherwise, iterate once more. 252 * Since 3*range = 11..._2, each iteration succeeds with 253 * probability >= .75. */ 254 if (BN_cmp(r, range) >= 0) { 255 if (!BN_sub(r, r, range)) 256 return 0; 257 if (BN_cmp(r, range) >= 0) 258 if (!BN_sub(r, r, range)) 259 return 0; 260 } 261 262 if (!--count) { 263 BNerror(BN_R_TOO_MANY_ITERATIONS); 264 return 0; 265 } 266 267 } while (BN_cmp(r, range) >= 0); 268 } else { 269 do { 270 /* range = 11..._2 or range = 101..._2 */ 271 if (!bn_rand(r, n, -1, 0)) 272 return 0; 273 274 if (!--count) { 275 BNerror(BN_R_TOO_MANY_ITERATIONS); 276 return 0; 277 } 278 } while (BN_cmp(r, range) >= 0); 279 } 280 281 return 1; 282} 283 284int 285BN_rand_range(BIGNUM *r, const BIGNUM *range) 286{ 287 return bn_rand_range(0, r, range); 288} 289LCRYPTO_ALIAS(BN_rand_range); 290 291int 292bn_rand_in_range(BIGNUM *rnd, const BIGNUM *lower_inc, const BIGNUM *upper_exc) 293{ 294 BIGNUM *len; 295 int ret = 0; 296 297 if ((len = BN_new()) == NULL) 298 goto err; 299 if (!BN_sub(len, upper_exc, lower_inc)) 300 goto err; 301 if (!BN_rand_range(rnd, len)) 302 goto err; 303 if (!BN_add(rnd, rnd, lower_inc)) 304 goto err; 305 306 ret = 1; 307 308 err: 309 BN_free(len); 310 311 return ret; 312} 313 314int 315bn_rand_interval(BIGNUM *rnd, BN_ULONG lower_word, const BIGNUM *upper_exc) 316{ 317 BIGNUM *lower_inc = NULL; 318 int ret = 0; 319 320 if ((lower_inc = BN_new()) == NULL) 321 goto err; 322 if (!BN_set_word(lower_inc, lower_word)) 323 goto err; 324 if (!bn_rand_in_range(rnd, lower_inc, upper_exc)) 325 goto err; 326 327 ret = 1; 328 329 err: 330 BN_free(lower_inc); 331 332 return ret; 333} 334 335int 336BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) 337{ 338 return bn_rand_range(1, r, range); 339} 340LCRYPTO_ALIAS(BN_pseudo_rand_range); 341