text: /* 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 "cryptlib.h"
  #include "bn_lcl.h"
  #include <openssl/rand.h>
  #ifdef OPENSSL_SYS_WINDOWS
  #include <time.h>
  #endif
  #include <string.h> //MS: for TINYCLR_SSL_MEMCPY
  
  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 */
  	TINYCLR_SSL_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);
  	}
  
  int     BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
  	{
  	return bnrand(0, rnd, bits, top, bottom);
  	}
  
  int     BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
  	{
  	return bnrand(1, rnd, bits, top, bottom);
  	}
  
  #if 1
  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, const 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;
  	}
  
  
  int	BN_rand_range(BIGNUM *r, const BIGNUM *range)
  	{
  	return bn_rand_range(0, r, range);
  	}
  
  int	BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
  	{
  	return bn_rand_range(1, r, range);
  	}
  