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 #include <stdio.h>
  60 #include <time.h>
  61 #include "cryptlib.h"
  62 #include "bn_lcl.h"
  63 #include <openssl/rand.h>
  64
  65 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
  66         {
  67         unsigned char *buf=NULL;
  68         int ret=0,bit,bytes,mask;
  69         time_t tim;
  70
  71         bytes=(bits+7)/8;
  72         bit=(bits-1)%8;
  73         mask=0xff<<bit;
  74
  75         buf=(unsigned char *)Malloc(bytes);
  76         if (buf == NULL)
  77                 {
  78                 BNerr(BN_F_BN_RAND,ERR_R_MALLOC_FAILURE);
  79                 goto err;
  80                 }
  81
  82         /* make a random number and set the top and bottom bits */
  83         time(&tim);
  84         RAND_add(&tim,sizeof(tim),0);
  85
  86         if (RAND_bytes(buf,(int)bytes) <= 0)
  87                 goto err;
  88         if (top)
  89                 {
  90                 if (bit == 0)
  91                         {
  92                         buf[0]=1;
  93                         buf[1]|=0x80;
  94                         }
  95                 else
  96                         {
  97                         buf[0]|=(3<<(bit-1));
  98                         buf[0]&= ~(mask<<1);
  99                         }
 100                 }
 101         else
 102                 {
 103                 buf[0]|=(1<<bit);
 104                 buf[0]&= ~(mask<<1);
 105                 }
 106         if (bottom) /* set bottom bits to whatever odd is */
 107                 buf[bytes-1]|=1;
 108         if (!BN_bin2bn(buf,bytes,rnd)) goto err;
 109         ret=1;
 110 err:
 111         if (buf != NULL)
 112                 {
 113                 memset(buf,0,bytes);
 114                 Free(buf);
 115                 }
 116         return(ret);
 117         }
 118