/* crypto/bn/bn_rand.c */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 * 

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 * 

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 * 

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from 

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 * 

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 * 

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

/* ====================================================================

 * Copyright (c) 1998-2001 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer. 

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    openssl-core@openssl.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com).

 *

 */

#include <stdio.h>

#include <time.h>

#include "cryptlib.h"

#include "bn_lcl.h"

#include <openssl/rand.h>

static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)

	{

	unsigned char *buf=NULL;

	int ret=0,bit,bytes,mask;

	time_t tim;

	if (bits == 0)

		{

		BN_zero(rnd);

		return 1;

		}

	bytes=(bits+7)/8;

	bit=(bits-1)%8;

	mask=0xff<<(bit+1);

	buf=(unsigned char *)OPENSSL_malloc(bytes);

	if (buf == NULL)

		{

		BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE);

		goto err;

		}

	/* make a random number and set the top and bottom bits */

	time(&tim);

	RAND_add(&tim,sizeof(tim),0.0);

	if (pseudorand)

		{

		if (RAND_pseudo_bytes(buf, bytes) == -1)

			goto err;

		}

	else

		{

		if (RAND_bytes(buf, bytes) <= 0)

			goto err;

		}

#if 1

	if (pseudorand == 2)

		{

		/* generate patterns that are more likely to trigger BN

		   library bugs */

		int i;

		unsigned char c;

		for (i = 0; i < bytes; i++)

			{

			RAND_pseudo_bytes(&c, 1);

			if (c >= 128 && i > 0)

				buf[i] = buf[i-1];

			else if (c < 42)

				buf[i] = 0;

			else if (c < 84)

				buf[i] = 255;

			}

		}

#endif

	if (top != -1)

		{

		if (top)

			{

			if (bit == 0)

				{

				buf[0]=1;

				buf[1]|=0x80;

				}

			else

				{

				buf[0]|=(3<<(bit-1));

				}

			}

		else

			{

			buf[0]|=(1<<bit);

			}

		}

	buf[0] &= ~mask;

	if (bottom) /* set bottom bit if requested */

		buf[bytes-1]|=1;

	if (!BN_bin2bn(buf,bytes,rnd)) goto err;

	ret=1;

err:

	if (buf != NULL)

		{

		OPENSSL_cleanse(buf,bytes);

		OPENSSL_free(buf);

		}

	bn_check_top(rnd);

	return(ret);

	}

EXPORT_C int     BN_rand(BIGNUM *rnd, int bits, int top, int bottom)

	{

	return bnrand(0, rnd, bits, top, bottom);

	}

EXPORT_C int     BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)

	{

	return bnrand(1, rnd, bits, top, bottom);

	}

#if 1

EXPORT_C int     BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)

	{

	return bnrand(2, rnd, bits, top, bottom);

	}

#endif

/* random number r:  0 <= r < range */

static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)

	{

	int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;

	int n;

	int count = 100;

	if (range->neg || BN_is_zero(range))

		{

		BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);

		return 0;

		}

	n = BN_num_bits(range); /* n > 0 */

	/* BN_is_bit_set(range, n - 1) always holds */

	if (n == 1)

		BN_zero(r);

	else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))

		{

		/* range = 100..._2,

		 * so  3*range (= 11..._2)  is exactly one bit longer than  range */

		do

			{

			if (!bn_rand(r, n + 1, -1, 0)) return 0;

			/* If  r < 3*range,  use  r := r MOD range

			 * (which is either  r, r - range,  or  r - 2*range).

			 * Otherwise, iterate once more.

			 * Since  3*range = 11..._2, each iteration succeeds with

			 * probability >= .75. */

			if (BN_cmp(r ,range) >= 0)

				{

				if (!BN_sub(r, r, range)) return 0;

				if (BN_cmp(r, range) >= 0)

					if (!BN_sub(r, r, range)) return 0;

				}

			if (!--count)

				{

				BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);

				return 0;

				}

			}

		while (BN_cmp(r, range) >= 0);

		}

	else

		{

		do

			{

			/* range = 11..._2  or  range = 101..._2 */

			if (!bn_rand(r, n, -1, 0)) return 0;

			if (!--count)

				{

				BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);

				return 0;

				}

			}

		while (BN_cmp(r, range) >= 0);

		}

	bn_check_top(r);

	return 1;

	}

EXPORT_C int	BN_rand_range(BIGNUM *r, BIGNUM *range)

	{

	return bn_rand_range(0, r, range);

	}

EXPORT_C int	BN_pseudo_rand_range(BIGNUM *r, BIGNUM *range)

	{

	return bn_rand_range(1, r, range);

	}