sl@0: /* crypto/bn/bn_rand.c */
sl@0: /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
sl@0:  * All rights reserved.
sl@0:  *
sl@0:  * This package is an SSL implementation written
sl@0:  * by Eric Young (eay@cryptsoft.com).
sl@0:  * The implementation was written so as to conform with Netscapes SSL.
sl@0:  * 
sl@0:  * This library is free for commercial and non-commercial use as long as
sl@0:  * the following conditions are aheared to.  The following conditions
sl@0:  * apply to all code found in this distribution, be it the RC4, RSA,
sl@0:  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
sl@0:  * included with this distribution is covered by the same copyright terms
sl@0:  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
sl@0:  * 
sl@0:  * Copyright remains Eric Young's, and as such any Copyright notices in
sl@0:  * the code are not to be removed.
sl@0:  * If this package is used in a product, Eric Young should be given attribution
sl@0:  * as the author of the parts of the library used.
sl@0:  * This can be in the form of a textual message at program startup or
sl@0:  * in documentation (online or textual) provided with the package.
sl@0:  * 
sl@0:  * Redistribution and use in source and binary forms, with or without
sl@0:  * modification, are permitted provided that the following conditions
sl@0:  * are met:
sl@0:  * 1. Redistributions of source code must retain the copyright
sl@0:  *    notice, this list of conditions and the following disclaimer.
sl@0:  * 2. Redistributions in binary form must reproduce the above copyright
sl@0:  *    notice, this list of conditions and the following disclaimer in the
sl@0:  *    documentation and/or other materials provided with the distribution.
sl@0:  * 3. All advertising materials mentioning features or use of this software
sl@0:  *    must display the following acknowledgement:
sl@0:  *    "This product includes cryptographic software written by
sl@0:  *     Eric Young (eay@cryptsoft.com)"
sl@0:  *    The word 'cryptographic' can be left out if the rouines from the library
sl@0:  *    being used are not cryptographic related :-).
sl@0:  * 4. If you include any Windows specific code (or a derivative thereof) from 
sl@0:  *    the apps directory (application code) you must include an acknowledgement:
sl@0:  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
sl@0:  * 
sl@0:  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
sl@0:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
sl@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
sl@0:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
sl@0:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
sl@0:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
sl@0:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
sl@0:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
sl@0:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
sl@0:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
sl@0:  * SUCH DAMAGE.
sl@0:  * 
sl@0:  * The licence and distribution terms for any publically available version or
sl@0:  * derivative of this code cannot be changed.  i.e. this code cannot simply be
sl@0:  * copied and put under another distribution licence
sl@0:  * [including the GNU Public Licence.]
sl@0:  */
sl@0: /* ====================================================================
sl@0:  * Copyright (c) 1998-2001 The OpenSSL Project.  All rights reserved.
sl@0:  *
sl@0:  * Redistribution and use in source and binary forms, with or without
sl@0:  * modification, are permitted provided that the following conditions
sl@0:  * are met:
sl@0:  *
sl@0:  * 1. Redistributions of source code must retain the above copyright
sl@0:  *    notice, this list of conditions and the following disclaimer. 
sl@0:  *
sl@0:  * 2. Redistributions in binary form must reproduce the above copyright
sl@0:  *    notice, this list of conditions and the following disclaimer in
sl@0:  *    the documentation and/or other materials provided with the
sl@0:  *    distribution.
sl@0:  *
sl@0:  * 3. All advertising materials mentioning features or use of this
sl@0:  *    software must display the following acknowledgment:
sl@0:  *    "This product includes software developed by the OpenSSL Project
sl@0:  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
sl@0:  *
sl@0:  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
sl@0:  *    endorse or promote products derived from this software without
sl@0:  *    prior written permission. For written permission, please contact
sl@0:  *    openssl-core@openssl.org.
sl@0:  *
sl@0:  * 5. Products derived from this software may not be called "OpenSSL"
sl@0:  *    nor may "OpenSSL" appear in their names without prior written
sl@0:  *    permission of the OpenSSL Project.
sl@0:  *
sl@0:  * 6. Redistributions of any form whatsoever must retain the following
sl@0:  *    acknowledgment:
sl@0:  *    "This product includes software developed by the OpenSSL Project
sl@0:  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
sl@0:  *
sl@0:  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
sl@0:  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
sl@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
sl@0:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
sl@0:  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
sl@0:  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
sl@0:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
sl@0:  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
sl@0:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
sl@0:  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
sl@0:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
sl@0:  * OF THE POSSIBILITY OF SUCH DAMAGE.
sl@0:  * ====================================================================
sl@0:  *
sl@0:  * This product includes cryptographic software written by Eric Young
sl@0:  * (eay@cryptsoft.com).  This product includes software written by Tim
sl@0:  * Hudson (tjh@cryptsoft.com).
sl@0:  *
sl@0:  */
sl@0: 
sl@0: #include <stdio.h>
sl@0: #include <time.h>
sl@0: #include "cryptlib.h"
sl@0: #include "bn_lcl.h"
sl@0: #include <openssl/rand.h>
sl@0: 
sl@0: static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
sl@0: 	{
sl@0: 	unsigned char *buf=NULL;
sl@0: 	int ret=0,bit,bytes,mask;
sl@0: 	time_t tim;
sl@0: 
sl@0: 	if (bits == 0)
sl@0: 		{
sl@0: 		BN_zero(rnd);
sl@0: 		return 1;
sl@0: 		}
sl@0: 
sl@0: 	bytes=(bits+7)/8;
sl@0: 	bit=(bits-1)%8;
sl@0: 	mask=0xff<<(bit+1);
sl@0: 
sl@0: 	buf=(unsigned char *)OPENSSL_malloc(bytes);
sl@0: 	if (buf == NULL)
sl@0: 		{
sl@0: 		BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE);
sl@0: 		goto err;
sl@0: 		}
sl@0: 
sl@0: 	/* make a random number and set the top and bottom bits */
sl@0: 	time(&tim);
sl@0: 	RAND_add(&tim,sizeof(tim),0.0);
sl@0: 
sl@0: 	if (pseudorand)
sl@0: 		{
sl@0: 		if (RAND_pseudo_bytes(buf, bytes) == -1)
sl@0: 			goto err;
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		if (RAND_bytes(buf, bytes) <= 0)
sl@0: 			goto err;
sl@0: 		}
sl@0: 
sl@0: #if 1
sl@0: 	if (pseudorand == 2)
sl@0: 		{
sl@0: 		/* generate patterns that are more likely to trigger BN
sl@0: 		   library bugs */
sl@0: 		int i;
sl@0: 		unsigned char c;
sl@0: 
sl@0: 		for (i = 0; i < bytes; i++)
sl@0: 			{
sl@0: 			RAND_pseudo_bytes(&c, 1);
sl@0: 			if (c >= 128 && i > 0)
sl@0: 				buf[i] = buf[i-1];
sl@0: 			else if (c < 42)
sl@0: 				buf[i] = 0;
sl@0: 			else if (c < 84)
sl@0: 				buf[i] = 255;
sl@0: 			}
sl@0: 		}
sl@0: #endif
sl@0: 
sl@0: 	if (top != -1)
sl@0: 		{
sl@0: 		if (top)
sl@0: 			{
sl@0: 			if (bit == 0)
sl@0: 				{
sl@0: 				buf[0]=1;
sl@0: 				buf[1]|=0x80;
sl@0: 				}
sl@0: 			else
sl@0: 				{
sl@0: 				buf[0]|=(3<<(bit-1));
sl@0: 				}
sl@0: 			}
sl@0: 		else
sl@0: 			{
sl@0: 			buf[0]|=(1<<bit);
sl@0: 			}
sl@0: 		}
sl@0: 	buf[0] &= ~mask;
sl@0: 	if (bottom) /* set bottom bit if requested */
sl@0: 		buf[bytes-1]|=1;
sl@0: 	if (!BN_bin2bn(buf,bytes,rnd)) goto err;
sl@0: 	ret=1;
sl@0: err:
sl@0: 	if (buf != NULL)
sl@0: 		{
sl@0: 		OPENSSL_cleanse(buf,bytes);
sl@0: 		OPENSSL_free(buf);
sl@0: 		}
sl@0: 	bn_check_top(rnd);
sl@0: 	return(ret);
sl@0: 	}
sl@0: 
sl@0: EXPORT_C int     BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
sl@0: 	{
sl@0: 	return bnrand(0, rnd, bits, top, bottom);
sl@0: 	}
sl@0: 
sl@0: EXPORT_C int     BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
sl@0: 	{
sl@0: 	return bnrand(1, rnd, bits, top, bottom);
sl@0: 	}
sl@0: 
sl@0: #if 1
sl@0: EXPORT_C int     BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
sl@0: 	{
sl@0: 	return bnrand(2, rnd, bits, top, bottom);
sl@0: 	}
sl@0: #endif
sl@0: 
sl@0: 
sl@0: /* random number r:  0 <= r < range */
sl@0: static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)
sl@0: 	{
sl@0: 	int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
sl@0: 	int n;
sl@0: 	int count = 100;
sl@0: 
sl@0: 	if (range->neg || BN_is_zero(range))
sl@0: 		{
sl@0: 		BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
sl@0: 		return 0;
sl@0: 		}
sl@0: 
sl@0: 	n = BN_num_bits(range); /* n > 0 */
sl@0: 
sl@0: 	/* BN_is_bit_set(range, n - 1) always holds */
sl@0: 
sl@0: 	if (n == 1)
sl@0: 		BN_zero(r);
sl@0: 	else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
sl@0: 		{
sl@0: 		/* range = 100..._2,
sl@0: 		 * so  3*range (= 11..._2)  is exactly one bit longer than  range */
sl@0: 		do
sl@0: 			{
sl@0: 			if (!bn_rand(r, n + 1, -1, 0)) return 0;
sl@0: 			/* If  r < 3*range,  use  r := r MOD range
sl@0: 			 * (which is either  r, r - range,  or  r - 2*range).
sl@0: 			 * Otherwise, iterate once more.
sl@0: 			 * Since  3*range = 11..._2, each iteration succeeds with
sl@0: 			 * probability >= .75. */
sl@0: 			if (BN_cmp(r ,range) >= 0)
sl@0: 				{
sl@0: 				if (!BN_sub(r, r, range)) return 0;
sl@0: 				if (BN_cmp(r, range) >= 0)
sl@0: 					if (!BN_sub(r, r, range)) return 0;
sl@0: 				}
sl@0: 
sl@0: 			if (!--count)
sl@0: 				{
sl@0: 				BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
sl@0: 				return 0;
sl@0: 				}
sl@0: 			
sl@0: 			}
sl@0: 		while (BN_cmp(r, range) >= 0);
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		do
sl@0: 			{
sl@0: 			/* range = 11..._2  or  range = 101..._2 */
sl@0: 			if (!bn_rand(r, n, -1, 0)) return 0;
sl@0: 
sl@0: 			if (!--count)
sl@0: 				{
sl@0: 				BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
sl@0: 				return 0;
sl@0: 				}
sl@0: 			}
sl@0: 		while (BN_cmp(r, range) >= 0);
sl@0: 		}
sl@0: 
sl@0: 	bn_check_top(r);
sl@0: 	return 1;
sl@0: 	}
sl@0: 
sl@0: 
sl@0: EXPORT_C int	BN_rand_range(BIGNUM *r, BIGNUM *range)
sl@0: 	{
sl@0: 	return bn_rand_range(0, r, range);
sl@0: 	}
sl@0: 
sl@0: EXPORT_C int	BN_pseudo_rand_range(BIGNUM *r, BIGNUM *range)
sl@0: 	{
sl@0: 	return bn_rand_range(1, r, range);
sl@0: 	}