1 /* $OpenBSD: bn_rand.c,v 1.16 2014/10/22 13:02:04 jsing 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 <time.h> 115 116 #include <openssl/err.h> 117 118 #include "bn_lcl.h" 119 120 static int 121 bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) 122 { 123 unsigned char *buf = NULL; 124 int ret = 0, bit, bytes, mask; 125 126 if (bits == 0) { 127 BN_zero(rnd); 128 return 1; 129 } 130 131 bytes = (bits + 7) / 8; 132 bit = (bits - 1) % 8; 133 mask = 0xff << (bit + 1); 134 135 buf = malloc(bytes); 136 if (buf == NULL) { 137 BNerr(BN_F_BNRAND, ERR_R_MALLOC_FAILURE); 138 goto err; 139 } 140 141 /* make a random number and set the top and bottom bits */ 142 arc4random_buf(buf, bytes); 143 144 #if 1 145 if (pseudorand == 2) { 146 /* generate patterns that are more likely to trigger BN 147 library bugs */ 148 int i; 149 unsigned char c; 150 151 for (i = 0; i < bytes; i++) { 152 arc4random_buf(&c, 1); 153 if (c >= 128 && i > 0) 154 buf[i] = buf[i - 1]; 155 else if (c < 42) 156 buf[i] = 0; 157 else if (c < 84) 158 buf[i] = 255; 159 } 160 } 161 #endif 162 163 if (top != -1) { 164 if (top) { 165 if (bit == 0) { 166 buf[0] = 1; 167 buf[1] |= 0x80; 168 } else { 169 buf[0] |= (3 << (bit - 1)); 170 } 171 } else { 172 buf[0] |= (1 << bit); 173 } 174 } 175 buf[0] &= ~mask; 176 if (bottom) /* set bottom bit if requested */ 177 buf[bytes - 1] |= 1; 178 if (!BN_bin2bn(buf, bytes, rnd)) 179 goto err; 180 ret = 1; 181 182 err: 183 if (buf != NULL) { 184 OPENSSL_cleanse(buf, bytes); 185 free(buf); 186 } 187 bn_check_top(rnd); 188 return (ret); 189 } 190 191 int 192 BN_rand(BIGNUM *rnd, int bits, int top, int bottom) 193 { 194 return bnrand(0, rnd, bits, top, bottom); 195 } 196 197 int 198 BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) 199 { 200 return bnrand(1, rnd, bits, top, bottom); 201 } 202 203 #if 1 204 int 205 BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) 206 { 207 return bnrand(2, rnd, bits, top, bottom); 208 } 209 #endif 210 211 212 /* random number r: 0 <= r < range */ 213 static int 214 bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) 215 { 216 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; 217 int n; 218 int count = 100; 219 220 if (range->neg || BN_is_zero(range)) { 221 BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE); 222 return 0; 223 } 224 225 n = BN_num_bits(range); /* n > 0 */ 226 227 /* BN_is_bit_set(range, n - 1) always holds */ 228 229 if (n == 1) 230 BN_zero(r); 231 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) { 232 /* range = 100..._2, 233 * so 3*range (= 11..._2) is exactly one bit longer than range */ 234 do { 235 if (!bn_rand(r, n + 1, -1, 0)) 236 return 0; 237 /* If r < 3*range, use r := r MOD range 238 * (which is either r, r - range, or r - 2*range). 239 * Otherwise, iterate once more. 240 * Since 3*range = 11..._2, each iteration succeeds with 241 * probability >= .75. */ 242 if (BN_cmp(r, range) >= 0) { 243 if (!BN_sub(r, r, range)) 244 return 0; 245 if (BN_cmp(r, range) >= 0) 246 if (!BN_sub(r, r, range)) 247 return 0; 248 } 249 250 if (!--count) { 251 BNerr(BN_F_BN_RAND_RANGE, 252 BN_R_TOO_MANY_ITERATIONS); 253 return 0; 254 } 255 256 } while (BN_cmp(r, range) >= 0); 257 } else { 258 do { 259 /* range = 11..._2 or range = 101..._2 */ 260 if (!bn_rand(r, n, -1, 0)) 261 return 0; 262 263 if (!--count) { 264 BNerr(BN_F_BN_RAND_RANGE, 265 BN_R_TOO_MANY_ITERATIONS); 266 return 0; 267 } 268 } while (BN_cmp(r, range) >= 0); 269 } 270 271 bn_check_top(r); 272 return 1; 273 } 274 275 int 276 BN_rand_range(BIGNUM *r, const BIGNUM *range) 277 { 278 return bn_rand_range(0, r, range); 279 } 280 281 int 282 BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) 283 { 284 return bn_rand_range(1, r, range); 285 } 286