1 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 2 * All rights reserved. 3 * 4 * This package is an SSL implementation written 5 * by Eric Young (eay (at) cryptsoft.com). 6 * The implementation was written so as to conform with Netscapes SSL. 7 * 8 * This library is free for commercial and non-commercial use as long as 9 * the following conditions are aheared to. The following conditions 10 * apply to all code found in this distribution, be it the RC4, RSA, 11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 12 * included with this distribution is covered by the same copyright terms 13 * except that the holder is Tim Hudson (tjh (at) cryptsoft.com). 14 * 15 * Copyright remains Eric Young's, and as such any Copyright notices in 16 * the code are not to be removed. 17 * If this package is used in a product, Eric Young should be given attribution 18 * as the author of the parts of the library used. 19 * This can be in the form of a textual message at program startup or 20 * in documentation (online or textual) provided with the package. 21 * 22 * Redistribution and use in source and binary forms, with or without 23 * modification, are permitted provided that the following conditions 24 * are met: 25 * 1. Redistributions of source code must retain the copyright 26 * notice, this list of conditions and the following disclaimer. 27 * 2. Redistributions in binary form must reproduce the above copyright 28 * notice, this list of conditions and the following disclaimer in the 29 * documentation and/or other materials provided with the distribution. 30 * 3. All advertising materials mentioning features or use of this software 31 * must display the following acknowledgement: 32 * "This product includes cryptographic software written by 33 * Eric Young (eay (at) cryptsoft.com)" 34 * The word 'cryptographic' can be left out if the rouines from the library 35 * being used are not cryptographic related :-). 36 * 4. If you include any Windows specific code (or a derivative thereof) from 37 * the apps directory (application code) you must include an acknowledgement: 38 * "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)" 39 * 40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 * 52 * The licence and distribution terms for any publically available version or 53 * derivative of this code cannot be changed. i.e. this code cannot simply be 54 * copied and put under another distribution licence 55 * [including the GNU Public Licence.] 56 */ 57 /* ==================================================================== 58 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved. 59 * 60 * Redistribution and use in source and binary forms, with or without 61 * modification, are permitted provided that the following conditions 62 * are met: 63 * 64 * 1. Redistributions of source code must retain the above copyright 65 * notice, this list of conditions and the following disclaimer. 66 * 67 * 2. Redistributions in binary form must reproduce the above copyright 68 * notice, this list of conditions and the following disclaimer in 69 * the documentation and/or other materials provided with the 70 * distribution. 71 * 72 * 3. All advertising materials mentioning features or use of this 73 * software must display the following acknowledgment: 74 * "This product includes software developed by the OpenSSL Project 75 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 76 * 77 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 78 * endorse or promote products derived from this software without 79 * prior written permission. For written permission, please contact 80 * openssl-core (at) openssl.org. 81 * 82 * 5. Products derived from this software may not be called "OpenSSL" 83 * nor may "OpenSSL" appear in their names without prior written 84 * permission of the OpenSSL Project. 85 * 86 * 6. Redistributions of any form whatsoever must retain the following 87 * acknowledgment: 88 * "This product includes software developed by the OpenSSL Project 89 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 90 * 91 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 92 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 93 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 94 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 95 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 96 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 97 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 98 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 99 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 100 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 101 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 102 * OF THE POSSIBILITY OF SUCH DAMAGE. 103 * ==================================================================== 104 * 105 * This product includes cryptographic software written by Eric Young 106 * (eay (at) cryptsoft.com). This product includes software written by Tim 107 * Hudson (tjh (at) cryptsoft.com). */ 108 109 #include <openssl/bn.h> 110 111 #include <string.h> 112 113 #include <openssl/err.h> 114 #include <openssl/mem.h> 115 #include <openssl/rand.h> 116 #include <openssl/type_check.h> 117 118 #include "internal.h" 119 #include "../../internal.h" 120 #include "../rand/internal.h" 121 122 123 static const uint8_t kDefaultAdditionalData[32] = {0}; 124 125 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) { 126 uint8_t *buf = NULL; 127 int ret = 0, bit, bytes, mask; 128 129 if (rnd == NULL) { 130 return 0; 131 } 132 133 if (top != BN_RAND_TOP_ANY && top != BN_RAND_TOP_ONE && 134 top != BN_RAND_TOP_TWO) { 135 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); 136 return 0; 137 } 138 139 if (bottom != BN_RAND_BOTTOM_ANY && bottom != BN_RAND_BOTTOM_ODD) { 140 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); 141 return 0; 142 } 143 144 if (bits == 0) { 145 BN_zero(rnd); 146 return 1; 147 } 148 149 bytes = (bits + 7) / 8; 150 bit = (bits - 1) % 8; 151 mask = 0xff << (bit + 1); 152 153 buf = OPENSSL_malloc(bytes); 154 if (buf == NULL) { 155 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); 156 goto err; 157 } 158 159 // Make a random number and set the top and bottom bits. 160 RAND_bytes(buf, bytes); 161 162 if (top != BN_RAND_TOP_ANY) { 163 if (top == BN_RAND_TOP_TWO && bits > 1) { 164 if (bit == 0) { 165 buf[0] = 1; 166 buf[1] |= 0x80; 167 } else { 168 buf[0] |= (3 << (bit - 1)); 169 } 170 } else { 171 buf[0] |= (1 << bit); 172 } 173 } 174 175 buf[0] &= ~mask; 176 177 // Set the bottom bit if requested, 178 if (bottom == BN_RAND_BOTTOM_ODD) { 179 buf[bytes - 1] |= 1; 180 } 181 182 if (!BN_bin2bn(buf, bytes, rnd)) { 183 goto err; 184 } 185 186 ret = 1; 187 188 err: 189 OPENSSL_free(buf); 190 return ret; 191 } 192 193 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) { 194 return BN_rand(rnd, bits, top, bottom); 195 } 196 197 // bn_less_than_word returns one if the number represented by |len| words at |a| 198 // is less than |b| and zero otherwise. It performs this computation in time 199 // independent of the value of |a|. |b| is assumed public. 200 static int bn_less_than_word(const BN_ULONG *a, size_t len, BN_ULONG b) { 201 if (b == 0) { 202 return 0; 203 } 204 if (len == 0) { 205 return 1; 206 } 207 208 // |a| < |b| iff a[1..len-1] are all zero and a[0] < b. 209 OPENSSL_COMPILE_ASSERT(sizeof(BN_ULONG) <= sizeof(crypto_word_t), 210 crypto_word_t_too_small); 211 crypto_word_t mask = 0; 212 for (size_t i = 1; i < len; i++) { 213 mask |= a[i]; 214 } 215 // |mask| is now zero iff a[1..len-1] are all zero. 216 mask = constant_time_is_zero_w(mask); 217 mask &= constant_time_lt_w(a[0], b); 218 return constant_time_select_int(mask, 1, 0); 219 } 220 221 int bn_in_range_words(const BN_ULONG *a, BN_ULONG min_inclusive, 222 const BN_ULONG *max_exclusive, size_t len) { 223 return bn_less_than_words(a, max_exclusive, len) && 224 !bn_less_than_word(a, len, min_inclusive); 225 } 226 227 int bn_rand_range_words(BN_ULONG *out, BN_ULONG min_inclusive, 228 const BN_ULONG *max_exclusive, size_t len, 229 const uint8_t additional_data[32]) { 230 // This function implements the equivalent of steps 4 through 7 of FIPS 186-4 231 // appendices B.4.2 and B.5.2. When called in those contexts, |max_exclusive| 232 // is n and |min_inclusive| is one. 233 234 // Compute the bit length of |max_exclusive| (step 1), in terms of a number of 235 // |words| worth of entropy to fill and a mask of bits to clear in the top 236 // word. 237 size_t words = len; 238 while (words > 0 && max_exclusive[words - 1] == 0) { 239 words--; 240 } 241 if (words == 0 || 242 (words == 1 && max_exclusive[0] <= min_inclusive)) { 243 OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE); 244 return 0; 245 } 246 BN_ULONG mask = max_exclusive[words - 1]; 247 // This sets all bits in |mask| below the most significant bit. 248 mask |= mask >> 1; 249 mask |= mask >> 2; 250 mask |= mask >> 4; 251 mask |= mask >> 8; 252 mask |= mask >> 16; 253 #if defined(OPENSSL_64_BIT) 254 mask |= mask >> 32; 255 #endif 256 257 // Fill any unused words with zero. 258 OPENSSL_memset(out + words, 0, (len - words) * sizeof(BN_ULONG)); 259 260 unsigned count = 100; 261 do { 262 if (!--count) { 263 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS); 264 return 0; 265 } 266 267 // Steps 4 and 5. Use |words| and |mask| together to obtain a string of N 268 // bits, where N is the bit length of |max_exclusive|. 269 RAND_bytes_with_additional_data((uint8_t *)out, words * sizeof(BN_ULONG), 270 additional_data); 271 out[words - 1] &= mask; 272 273 // If out >= max_exclusive or out < min_inclusive, retry. This implements 274 // the equivalent of steps 6 and 7 without leaking the value of |out|. 275 } while (!bn_in_range_words(out, min_inclusive, max_exclusive, words)); 276 return 1; 277 } 278 279 int BN_rand_range_ex(BIGNUM *r, BN_ULONG min_inclusive, 280 const BIGNUM *max_exclusive) { 281 if (!bn_wexpand(r, max_exclusive->top) || 282 !bn_rand_range_words(r->d, min_inclusive, max_exclusive->d, 283 max_exclusive->top, kDefaultAdditionalData)) { 284 return 0; 285 } 286 287 r->neg = 0; 288 r->top = max_exclusive->top; 289 bn_correct_top(r); 290 return 1; 291 } 292 293 int BN_rand_range(BIGNUM *r, const BIGNUM *range) { 294 return BN_rand_range_ex(r, 0, range); 295 } 296 297 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) { 298 return BN_rand_range(r, range); 299 } 300
