crypto/bn/bn_rand.c

   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 #define OPENSSL_FIPSAPI
 113
 114 #include <stdio.h>
 115 #include <time.h>
 116 #include "cryptlib.h"
 117 #include "bn_lcl.h"
 118 #include <openssl/rand.h>
 119
 120 static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
 121         {
 122         unsigned char *buf=NULL;
 123         int ret=0,bit,bytes,mask;
 124         time_t tim;
 125
 126         if (bits == 0)
 127                 {
 128                 BN_zero(rnd);
 129                 return 1;
 130                 }
 131
 132         bytes=(bits+7)/8;
 133         bit=(bits-1)%8;
 134         mask=0xff<<(bit+1);
 135
 136         buf=(unsigned char *)OPENSSL_malloc(bytes);
 137         if (buf == NULL)
 138                 {
 139                 BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE);
 140                 goto err;
 141                 }
 142
 143         /* make a random number and set the top and bottom bits */
 144         time(&tim);
 145         RAND_add(&tim,sizeof(tim),0.0);
 146
 147         if (pseudorand)
 148                 {
 149                 if (RAND_pseudo_bytes(buf, bytes) == -1)
 150                         goto err;
 151                 }
 152         else
 153                 {
 154                 if (RAND_bytes(buf, bytes) <= 0)
 155                         goto err;
 156                 }
 157
 158 #if 1
 159         if (pseudorand == 2)
 160                 {
 161                 /* generate patterns that are more likely to trigger BN
 162                    library bugs */
 163                 int i;
 164                 unsigned char c;
 165
 166                 for (i = 0; i < bytes; i++)
 167                         {
 168                         RAND_pseudo_bytes(&c, 1);
 169                         if (c >= 128 && i > 0)
 170                                 buf[i] = buf[i-1];
 171                         else if (c < 42)
 172                                 buf[i] = 0;
 173                         else if (c < 84)
 174                                 buf[i] = 255;
 175                         }
 176                 }
 177 #endif
 178
 179         if (top != -1)
 180                 {
 181                 if (top)
 182                         {
 183                         if (bit == 0)
 184                                 {
 185                                 buf[0]=1;
 186                                 buf[1]|=0x80;
 187                                 }
 188                         else
 189                                 {
 190                                 buf[0]|=(3<<(bit-1));
 191                                 }
 192                         }
 193                 else
 194                         {
 195                         buf[0]|=(1<<bit);
 196                         }
 197                 }
 198         buf[0] &= ~mask;
 199         if (bottom) /* set bottom bit if requested */
 200                 buf[bytes-1]|=1;
 201         if (!BN_bin2bn(buf,bytes,rnd)) goto err;
 202         ret=1;
 203 err:
 204         if (buf != NULL)
 205                 {
 206                 OPENSSL_cleanse(buf,bytes);
 207                 OPENSSL_free(buf);
 208                 }
 209         bn_check_top(rnd);
 210         return(ret);
 211         }
 212
 213 int     BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
 214         {
 215         return bnrand(0, rnd, bits, top, bottom);
 216         }
 217
 218 int     BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
 219         {
 220         return bnrand(1, rnd, bits, top, bottom);
 221         }
 222
 223 #if 1
 224 int     BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
 225         {
 226         return bnrand(2, rnd, bits, top, bottom);
 227         }
 228 #endif
 229
 230
 231 /* random number r:  0 <= r < range */
 232 static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range)
 233         {
 234         int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
 235         int n;
 236         int count = 100;
 237
 238         if (range->neg || BN_is_zero(range))
 239                 {
 240                 BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
 241                 return 0;
 242                 }
 243
 244         n = BN_num_bits(range); /* n > 0 */
 245
 246         /* BN_is_bit_set(range, n - 1) always holds */
 247
 248         if (n == 1)
 249                 BN_zero(r);
 250 #ifdef OPENSSL_FIPS
 251         /* FIPS 186-3 is picky about how random numbers for keys etc are
 252          * generated. So we just use the second case which is equivalent to
 253          * "Generation by Testing Candidates" mentioned in B.1.2 et al.
 254          */
 255         else if (!FIPS_mode() && !BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
 256 #else
 257         else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
 258 #endif
 259                 {
 260                 /* range = 100..._2,
 261                  * so  3*range (= 11..._2)  is exactly one bit longer than  range */
 262                 do
 263                         {
 264                         if (!bn_rand(r, n + 1, -1, 0)) return 0;
 265                         /* If  r < 3*range,  use  r := r MOD range
 266                          * (which is either  r, r - range,  or  r - 2*range).
 267                          * Otherwise, iterate once more.
 268                          * Since  3*range = 11..._2, each iteration succeeds with
 269                          * probability >= .75. */
 270                         if (BN_cmp(r ,range) >= 0)
 271                                 {
 272                                 if (!BN_sub(r, r, range)) return 0;
 273                                 if (BN_cmp(r, range) >= 0)
 274                                         if (!BN_sub(r, r, range)) return 0;
 275                                 }
 276
 277                         if (!--count)
 278                                 {
 279                                 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
 280                                 return 0;
 281                                 }
 282
 283                         }
 284                 while (BN_cmp(r, range) >= 0);
 285                 }
 286         else
 287                 {
 288                 do
 289                         {
 290                         /* range = 11..._2  or  range = 101..._2 */
 291                         if (!bn_rand(r, n, -1, 0)) return 0;
 292
 293                         if (!--count)
 294                                 {
 295                                 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
 296                                 return 0;
 297                                 }
 298                         }
 299                 while (BN_cmp(r, range) >= 0);
 300                 }
 301
 302         bn_check_top(r);
 303         return 1;
 304         }
 305
 306
 307 int     BN_rand_range(BIGNUM *r, const BIGNUM *range)
 308         {
 309         return bn_rand_range(0, r, range);
 310         }
 311
 312 int     BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
 313         {
 314         return bn_rand_range(1, r, range);
 315         }