1 /* $OpenBSD: bn_rand.c,v 1.25 2021/08/31 11:19:19 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 <stdio.h> 113 #include <stdlib.h> 114 #include <string.h> 115 #include <time.h> 116 117 #include <openssl/err.h> 118 119 #include "bn_lcl.h" 120 121 static int 122 bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) 123 { 124 unsigned char *buf = NULL; 125 int ret = 0, bit, bytes, mask; 126 127 if (rnd == NULL) { 128 BNerror(ERR_R_PASSED_NULL_PARAMETER); 129 return (0); 130 } 131 132 if (bits < 0 || (bits == 1 && top > 0)) { 133 BNerror(BN_R_BITS_TOO_SMALL); 134 return (0); 135 } 136 137 if (bits == 0) { 138 BN_zero(rnd); 139 return (1); 140 } 141 142 bytes = (bits + 7) / 8; 143 bit = (bits - 1) % 8; 144 mask = 0xff << (bit + 1); 145 146 buf = malloc(bytes); 147 if (buf == NULL) { 148 BNerror(ERR_R_MALLOC_FAILURE); 149 goto err; 150 } 151 152 /* make a random number and set the top and bottom bits */ 153 arc4random_buf(buf, bytes); 154 155 #if 1 156 if (pseudorand == 2) { 157 /* generate patterns that are more likely to trigger BN 158 library bugs */ 159 int i; 160 unsigned char c; 161 162 for (i = 0; i < bytes; i++) { 163 arc4random_buf(&c, 1); 164 if (c >= 128 && i > 0) 165 buf[i] = buf[i - 1]; 166 else if (c < 42) 167 buf[i] = 0; 168 else if (c < 84) 169 buf[i] = 255; 170 } 171 } 172 #endif 173 174 if (top > 0) { 175 if (bit == 0) { 176 buf[0] = 1; 177 buf[1] |= 0x80; 178 } else { 179 buf[0] |= (3 << (bit - 1)); 180 } 181 } 182 if (top == 0) 183 buf[0] |= (1 << bit); 184 buf[0] &= ~mask; 185 if (bottom) /* set bottom bit if requested */ 186 buf[bytes - 1] |= 1; 187 if (BN_bin2bn(buf, bytes, rnd) == NULL) 188 goto err; 189 ret = 1; 190 191 err: 192 freezero(buf, bytes); 193 bn_check_top(rnd); 194 return (ret); 195 } 196 197 int 198 BN_rand(BIGNUM *rnd, int bits, int top, int bottom) 199 { 200 return bnrand(0, rnd, bits, top, bottom); 201 } 202 203 int 204 BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) 205 { 206 return bnrand(1, rnd, bits, top, bottom); 207 } 208 209 #if 1 210 int 211 BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) 212 { 213 return bnrand(2, rnd, bits, top, bottom); 214 } 215 #endif 216 217 218 /* random number r: 0 <= r < range */ 219 static int 220 bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) 221 { 222 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; 223 int n; 224 int count = 100; 225 226 if (range->neg || BN_is_zero(range)) { 227 BNerror(BN_R_INVALID_RANGE); 228 return 0; 229 } 230 231 n = BN_num_bits(range); /* n > 0 */ 232 233 /* BN_is_bit_set(range, n - 1) always holds */ 234 235 if (n == 1) 236 BN_zero(r); 237 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) { 238 /* range = 100..._2, 239 * so 3*range (= 11..._2) is exactly one bit longer than range */ 240 do { 241 if (!bn_rand(r, n + 1, -1, 0)) 242 return 0; 243 /* If r < 3*range, use r := r MOD range 244 * (which is either r, r - range, or r - 2*range). 245 * Otherwise, iterate once more. 246 * Since 3*range = 11..._2, each iteration succeeds with 247 * probability >= .75. */ 248 if (BN_cmp(r, range) >= 0) { 249 if (!BN_sub(r, r, range)) 250 return 0; 251 if (BN_cmp(r, range) >= 0) 252 if (!BN_sub(r, r, range)) 253 return 0; 254 } 255 256 if (!--count) { 257 BNerror(BN_R_TOO_MANY_ITERATIONS); 258 return 0; 259 } 260 261 } while (BN_cmp(r, range) >= 0); 262 } else { 263 do { 264 /* range = 11..._2 or range = 101..._2 */ 265 if (!bn_rand(r, n, -1, 0)) 266 return 0; 267 268 if (!--count) { 269 BNerror(BN_R_TOO_MANY_ITERATIONS); 270 return 0; 271 } 272 } while (BN_cmp(r, range) >= 0); 273 } 274 275 bn_check_top(r); 276 return 1; 277 } 278 279 int 280 BN_rand_range(BIGNUM *r, const BIGNUM *range) 281 { 282 return bn_rand_range(0, r, range); 283 } 284 285 int 286 bn_rand_interval(BIGNUM *rnd, const BIGNUM *lower_inc, const BIGNUM *upper_exc) 287 { 288 BIGNUM *len = NULL; 289 int ret = 0; 290 291 if (BN_cmp(lower_inc, upper_exc) >= 0) 292 goto err; 293 294 if ((len = BN_new()) == NULL) 295 goto err; 296 297 if (!BN_sub(len, upper_exc, lower_inc)) 298 goto err; 299 300 if (!bn_rand_range(0, rnd, len)) 301 goto err; 302 303 if (!BN_add(rnd, rnd, lower_inc)) 304 goto err; 305 306 ret = 1; 307 err: 308 BN_free(len); 309 return ret; 310 } 311 312 int 313 BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) 314 { 315 return bn_rand_range(1, r, range); 316 } 317