bn_rand.c revision 59191 
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
65static int bnrand(int pseudorand, 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 (pseudorand)
87		{
88		if (RAND_pseudo_bytes(buf, bytes) == -1)
89			goto err;
90		}
91	else
92		{
93		if (RAND_bytes(buf, bytes) <= 0)
94			goto err;
95		}
96
97	if (top)
98		{
99		if (bit == 0)
100			{
101			buf[0]=1;
102			buf[1]|=0x80;
103			}
104		else
105			{
106			buf[0]|=(3<<(bit-1));
107			buf[0]&= ~(mask<<1);
108			}
109		}
110	else
111		{
112		buf[0]|=(1<<bit);
113		buf[0]&= ~(mask<<1);
114		}
115	if (bottom) /* set bottom bits to whatever odd is */
116		buf[bytes-1]|=1;
117	if (!BN_bin2bn(buf,bytes,rnd)) goto err;
118	ret=1;
119err:
120	if (buf != NULL)
121		{
122		memset(buf,0,bytes);
123		Free(buf);
124		}
125	return(ret);
126	}
127
128int     BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
129	{
130	return bnrand(0, rnd, bits, top, bottom);
131	}
132
133int     BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
134	{
135	return bnrand(1, rnd, bits, top, bottom);
136	}
137