rand_key.c

/* crypto/des/rand_key.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.]
 */

#include "des_locl.h"
#include <time.h>

static int seed=0;
static des_cblock init;

void des_random_seed(des_cblock *key)
	{
	memcpy(&init,key,sizeof(des_cblock));
	seed=1;
	}

void des_random_key(des_cblock *ret)
	{
	des_key_schedule ks;
	static DES_LONG c=0;
	static unsigned short pid=0;
	static des_cblock data={0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef};
	des_cblock key;
	unsigned char *p;
	DES_LONG t;
	int i;

#ifdef MSDOS
	pid=1;
#else
	if (!pid) pid=getpid();
#endif
	p=key;
	if (seed)
		{
		for (i=0; i<8; i++)
			{
			data[i] ^= init[i];
			init[i]=0;
			}
		seed=0;
		}
	t=(DES_LONG)time(NULL);
	l2c(t,p);
	t=(DES_LONG)((pid)|((c++)<<16));
	l2c(t,p);

	des_set_odd_parity(&data);
	des_set_key_unchecked(&data,ks);
	des_cbc_cksum(key,&key,sizeof(key),ks,&data);

	des_set_odd_parity(&key);
	des_set_key_unchecked(&key,ks);
	des_cbc_cksum(key,&data,sizeof(key),ks,&key);

	memcpy(ret,data,sizeof(key));
	memset(key,0,sizeof(key));
	memset(ks,0,sizeof(ks));
	t=0;
	}