bn_rand.c revision 306196
1/* crypto/bn/bn_rand.c */ 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 <time.h> 114#include "cryptlib.h" 115#include "bn_lcl.h" 116#include <openssl/rand.h> 117 118static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) 119{ 120 unsigned char *buf = NULL; 121 int ret = 0, bit, bytes, mask; 122 time_t tim; 123 124 if (bits < 0 || (bits == 1 && top > 0)) { 125 BNerr(BN_F_BNRAND, BN_R_BITS_TOO_SMALL); 126 return 0; 127 } 128 129 if (bits == 0) { 130 BN_zero(rnd); 131 return 1; 132 } 133 134 bytes = (bits + 7) / 8; 135 bit = (bits - 1) % 8; 136 mask = 0xff << (bit + 1); 137 138 buf = (unsigned char *)OPENSSL_malloc(bytes); 139 if (buf == NULL) { 140 BNerr(BN_F_BNRAND, ERR_R_MALLOC_FAILURE); 141 goto err; 142 } 143 144 /* make a random number and set the top and bottom bits */ 145 time(&tim); 146 RAND_add(&tim, sizeof(tim), 0.0); 147 148 /* We ignore the value of pseudorand and always call RAND_bytes */ 149 if (RAND_bytes(buf, bytes) <= 0) 150 goto err; 151 152#if 1 153 if (pseudorand == 2) { 154 /* 155 * generate patterns that are more likely to trigger BN library bugs 156 */ 157 int i; 158 unsigned char c; 159 160 for (i = 0; i < bytes; i++) { 161 if (RAND_pseudo_bytes(&c, 1) < 0) 162 goto err; 163 if (c >= 128 && i > 0) 164 buf[i] = buf[i - 1]; 165 else if (c < 42) 166 buf[i] = 0; 167 else if (c < 84) 168 buf[i] = 255; 169 } 170 } 171#endif 172 173 if (top >= 0) { 174 if (top) { 175 if (bit == 0) { 176 buf[0] = 1; 177 buf[1] |= 0x80; 178 } else { 179 buf[0] |= (3 << (bit - 1)); 180 } 181 } else { 182 buf[0] |= (1 << bit); 183 } 184 } 185 buf[0] &= ~mask; 186 if (bottom) /* set bottom bit if requested */ 187 buf[bytes - 1] |= 1; 188 if (!BN_bin2bn(buf, bytes, rnd)) 189 goto err; 190 ret = 1; 191 err: 192 if (buf != NULL) { 193 OPENSSL_cleanse(buf, bytes); 194 OPENSSL_free(buf); 195 } 196 bn_check_top(rnd); 197 return (ret); 198} 199 200int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) 201{ 202 return bnrand(0, rnd, bits, top, bottom); 203} 204 205int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) 206{ 207 return bnrand(1, rnd, bits, top, bottom); 208} 209 210#if 1 211int 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/* random number r: 0 <= r < range */ 218static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) 219{ 220 int (*bn_rand) (BIGNUM *, int, int, int) = 221 pseudo ? BN_pseudo_rand : BN_rand; 222 int n; 223 int count = 100; 224 225 if (range->neg || BN_is_zero(range)) { 226 BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE); 227 return 0; 228 } 229 230 n = BN_num_bits(range); /* n > 0 */ 231 232 /* BN_is_bit_set(range, n - 1) always holds */ 233 234 if (n == 1) 235 BN_zero(r); 236 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) { 237 /* 238 * range = 100..._2, so 3*range (= 11..._2) is exactly one bit longer 239 * than range 240 */ 241 do { 242 if (!bn_rand(r, n + 1, -1, 0)) 243 return 0; 244 /* 245 * If r < 3*range, use r := r MOD range (which is either r, r - 246 * range, or r - 2*range). Otherwise, iterate once more. Since 247 * 3*range = 11..._2, each iteration succeeds with probability >= 248 * .75. 249 */ 250 if (BN_cmp(r, range) >= 0) { 251 if (!BN_sub(r, r, range)) 252 return 0; 253 if (BN_cmp(r, range) >= 0) 254 if (!BN_sub(r, r, range)) 255 return 0; 256 } 257 258 if (!--count) { 259 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); 260 return 0; 261 } 262 263 } 264 while (BN_cmp(r, range) >= 0); 265 } else { 266 do { 267 /* range = 11..._2 or range = 101..._2 */ 268 if (!bn_rand(r, n, -1, 0)) 269 return 0; 270 271 if (!--count) { 272 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); 273 return 0; 274 } 275 } 276 while (BN_cmp(r, range) >= 0); 277 } 278 279 bn_check_top(r); 280 return 1; 281} 282 283int BN_rand_range(BIGNUM *r, const BIGNUM *range) 284{ 285 return bn_rand_range(0, r, range); 286} 287 288int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) 289{ 290 return bn_rand_range(1, r, range); 291} 292