1 /* crypto/bn/bn_rand.c */ 2 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay (at) 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 (at) 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 (at) 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 (at) 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 (at) 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 (at) cryptsoft.com). This product includes software written by Tim 108 * Hudson (tjh (at) 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 #include <openssl/sha.h> 118 119 static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) 120 { 121 unsigned char *buf=NULL; 122 int ret=0,bit,bytes,mask; 123 time_t tim; 124 125 if (bits == 0) 126 { 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=(unsigned char *)OPENSSL_malloc(bytes); 136 if (buf == NULL) 137 { 138 BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE); 139 goto err; 140 } 141 142 /* make a random number and set the top and bottom bits */ 143 time(&tim); 144 RAND_add(&tim,sizeof(tim),0.0); 145 146 if (pseudorand) 147 { 148 if (RAND_pseudo_bytes(buf, bytes) == -1) 149 goto err; 150 } 151 else 152 { 153 if (RAND_bytes(buf, bytes) <= 0) 154 goto err; 155 } 156 157 #if 1 158 if (pseudorand == 2) 159 { 160 /* generate patterns that are more likely to trigger BN 161 library bugs */ 162 int i; 163 unsigned char c; 164 165 for (i = 0; i < bytes; i++) 166 { 167 RAND_pseudo_bytes(&c, 1); 168 if (c >= 128 && i > 0) 169 buf[i] = buf[i-1]; 170 else if (c < 42) 171 buf[i] = 0; 172 else if (c < 84) 173 buf[i] = 255; 174 } 175 } 176 #endif 177 178 if (top != -1) 179 { 180 if (top) 181 { 182 if (bit == 0) 183 { 184 buf[0]=1; 185 buf[1]|=0x80; 186 } 187 else 188 { 189 buf[0]|=(3<<(bit-1)); 190 } 191 } 192 else 193 { 194 buf[0]|=(1<<bit); 195 } 196 } 197 buf[0] &= ~mask; 198 if (bottom) /* set bottom bit if requested */ 199 buf[bytes-1]|=1; 200 if (!BN_bin2bn(buf,bytes,rnd)) goto err; 201 ret=1; 202 err: 203 if (buf != NULL) 204 { 205 OPENSSL_cleanse(buf,bytes); 206 OPENSSL_free(buf); 207 } 208 bn_check_top(rnd); 209 return(ret); 210 } 211 212 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) 213 { 214 return bnrand(0, rnd, bits, top, bottom); 215 } 216 217 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) 218 { 219 return bnrand(1, rnd, bits, top, bottom); 220 } 221 222 #if 1 223 int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) 224 { 225 return bnrand(2, rnd, bits, top, bottom); 226 } 227 #endif 228 229 230 /* random number r: 0 <= r < range */ 231 static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) 232 { 233 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; 234 int n; 235 int count = 100; 236 237 if (range->neg || BN_is_zero(range)) 238 { 239 BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE); 240 return 0; 241 } 242 243 n = BN_num_bits(range); /* n > 0 */ 244 245 /* BN_is_bit_set(range, n - 1) always holds */ 246 247 if (n == 1) 248 BN_zero(r); 249 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) 250 { 251 /* range = 100..._2, 252 * so 3*range (= 11..._2) is exactly one bit longer than range */ 253 do 254 { 255 if (!bn_rand(r, n + 1, -1, 0)) return 0; 256 /* If r < 3*range, use r := r MOD range 257 * (which is either r, r - range, or r - 2*range). 258 * Otherwise, iterate once more. 259 * Since 3*range = 11..._2, each iteration succeeds with 260 * probability >= .75. */ 261 if (BN_cmp(r ,range) >= 0) 262 { 263 if (!BN_sub(r, r, range)) return 0; 264 if (BN_cmp(r, range) >= 0) 265 if (!BN_sub(r, r, range)) return 0; 266 } 267 268 if (!--count) 269 { 270 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); 271 return 0; 272 } 273 274 } 275 while (BN_cmp(r, range) >= 0); 276 } 277 else 278 { 279 do 280 { 281 /* range = 11..._2 or range = 101..._2 */ 282 if (!bn_rand(r, n, -1, 0)) return 0; 283 284 if (!--count) 285 { 286 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS); 287 return 0; 288 } 289 } 290 while (BN_cmp(r, range) >= 0); 291 } 292 293 bn_check_top(r); 294 return 1; 295 } 296 297 298 int BN_rand_range(BIGNUM *r, const BIGNUM *range) 299 { 300 return bn_rand_range(0, r, range); 301 } 302 303 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) 304 { 305 return bn_rand_range(1, r, range); 306 } 307 308 #ifndef OPENSSL_NO_SHA512 309 /* BN_generate_dsa_nonce generates a random number 0 <= out < range. Unlike 310 * BN_rand_range, it also includes the contents of |priv| and |message| in the 311 * generation so that an RNG failure isn't fatal as long as |priv| remains 312 * secret. This is intended for use in DSA and ECDSA where an RNG weakness 313 * leads directly to private key exposure unless this function is used. */ 314 int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range, const BIGNUM* priv, 315 const unsigned char *message, size_t message_len, 316 BN_CTX *ctx) 317 { 318 SHA512_CTX sha; 319 /* We use 512 bits of random data per iteration to 320 * ensure that we have at least |range| bits of randomness. */ 321 unsigned char random_bytes[64]; 322 unsigned char digest[SHA512_DIGEST_LENGTH]; 323 unsigned done, todo; 324 /* We generate |range|+8 bytes of random output. */ 325 const unsigned num_k_bytes = BN_num_bytes(range) + 8; 326 unsigned char private_bytes[96]; 327 unsigned char *k_bytes; 328 int ret = 0; 329 330 k_bytes = OPENSSL_malloc(num_k_bytes); 331 if (!k_bytes) 332 goto err; 333 334 /* We copy |priv| into a local buffer to avoid exposing its length. */ 335 todo = sizeof(priv->d[0])*priv->top; 336 if (todo > sizeof(private_bytes)) 337 { 338 /* No reasonable DSA or ECDSA key should have a private key 339 * this large and we don't handle this case in order to avoid 340 * leaking the length of the private key. */ 341 BNerr(BN_F_BN_GENERATE_DSA_NONCE, BN_R_PRIVATE_KEY_TOO_LARGE); 342 goto err; 343 } 344 memcpy(private_bytes, priv->d, todo); 345 memset(private_bytes + todo, 0, sizeof(private_bytes) - todo); 346 347 for (done = 0; done < num_k_bytes;) { 348 if (RAND_bytes(random_bytes, sizeof(random_bytes)) != 1) 349 goto err; 350 SHA512_Init(&sha); 351 SHA512_Update(&sha, &done, sizeof(done)); 352 SHA512_Update(&sha, private_bytes, sizeof(private_bytes)); 353 SHA512_Update(&sha, message, message_len); 354 SHA512_Update(&sha, random_bytes, sizeof(random_bytes)); 355 SHA512_Final(digest, &sha); 356 357 todo = num_k_bytes - done; 358 if (todo > SHA512_DIGEST_LENGTH) 359 todo = SHA512_DIGEST_LENGTH; 360 memcpy(k_bytes + done, digest, todo); 361 done += todo; 362 } 363 364 if (!BN_bin2bn(k_bytes, num_k_bytes, out)) 365 goto err; 366 if (BN_mod(out, out, range, ctx) != 1) 367 goto err; 368 ret = 1; 369 370 err: 371 if (k_bytes) 372 OPENSSL_free(k_bytes); 373 return ret; 374 } 375 #endif /* OPENSSL_NO_SHA512 */ 376
