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) 125 { 126 BN_zero(rnd); 127 return 1; 128 } 129 130 bytes=(bits+7)/8; 131 bit=(bits-1)%8; 132 mask=0xff<<(bit+1); 133 134 buf=(unsigned char *)OPENSSL_malloc(bytes); 135 if (buf == NULL) 136 { 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 time(&tim); 143 RAND_add(&tim,sizeof(tim),0.0); 144 145 if (pseudorand) 146 { 147 if (RAND_pseudo_bytes(buf, bytes) == -1) 148 goto err; 149 } 150 else 151 { 152 if (RAND_bytes(buf, bytes) <= 0) 153 goto err; 154 } 155 156#if 1 157 if (pseudorand == 2) 158 { 159 /* generate patterns that are more likely to trigger BN 160 library bugs */ 161 int i; 162 unsigned char c; 163 164 for (i = 0; i < bytes; i++) 165 { 166 RAND_pseudo_bytes(&c, 1); 167 if (c >= 128 && i > 0) 168 buf[i] = buf[i-1]; 169 else if (c < 42) 170 buf[i] = 0; 171 else if (c < 84) 172 buf[i] = 255; 173 } 174 } 175#endif 176 177 if (top != -1) 178 { 179 if (top) 180 { 181 if (bit == 0) 182 { 183 buf[0]=1; 184 buf[1]|=0x80; 185 } 186 else 187 { 188 buf[0]|=(3<<(bit-1)); 189 } 190 } 191 else 192 { 193 buf[0]|=(1<<bit); 194 } 195 } 196 buf[0] &= ~mask; 197 if (bottom) /* set bottom bit if requested */ 198 buf[bytes-1]|=1; 199 if (!BN_bin2bn(buf,bytes,rnd)) goto err; 200 ret=1; 201err: 202 if (buf != NULL) 203 { 204 OPENSSL_cleanse(buf,bytes); 205 OPENSSL_free(buf); 206 } 207 bn_check_top(rnd); 208 return(ret); 209 } 210 211int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) 212 { 213 return bnrand(0, rnd, bits, top, bottom); 214 } 215 216int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) 217 { 218 return bnrand(1, rnd, bits, top, bottom); 219 } 220 221#if 1 222int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) 223 { 224 return bnrand(2, rnd, bits, top, bottom); 225 } 226#endif 227 228 229/* random number r: 0 <= r < range */ 230static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range) 231 { 232 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; 233 int n; 234 int count = 100; 235 236 if (range->neg || BN_is_zero(range)) 237 { 238 BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE); 239 return 0; 240 } 241 242 n = BN_num_bits(range); /* n > 0 */ 243 244 /* BN_is_bit_set(range, n - 1) always holds */ 245 246 if (n == 1) 247 BN_zero(r); 248 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) 249 { 250 /* range = 100..._2, 251 * so 3*range (= 11..._2) is exactly one bit longer than range */ 252 do 253 { 254 if (!bn_rand(r, n + 1, -1, 0)) return 0; 255 /* If r < 3*range, use r := r MOD range 256 * (which is either r, r - range, or r - 2*range). 257 * Otherwise, iterate once more. 258 * Since 3*range = 11..._2, each iteration succeeds with 259 * probability >= .75. */ 260 if (BN_cmp(r ,range) >= 0) 261 { 262 if (!BN_sub(r, r, range)) return 0; 263 if (BN_cmp(r, range) >= 0) 264 if (!BN_sub(r, r, range)) return 0; 265 } 266 267 if (!--count) 268 { 269 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); 270 return 0; 271 } 272 273 } 274 while (BN_cmp(r, range) >= 0); 275 } 276 else 277 { 278 do 279 { 280 /* range = 11..._2 or range = 101..._2 */ 281 if (!bn_rand(r, n, -1, 0)) return 0; 282 283 if (!--count) 284 { 285 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); 286 return 0; 287 } 288 } 289 while (BN_cmp(r, range) >= 0); 290 } 291 292 bn_check_top(r); 293 return 1; 294 } 295 296 297int BN_rand_range(BIGNUM *r, BIGNUM *range) 298 { 299 return bn_rand_range(0, r, range); 300 } 301 302int BN_pseudo_rand_range(BIGNUM *r, BIGNUM *range) 303 { 304 return bn_rand_range(1, r, range); 305 } 306