set_key.c

This a good VPN source

/* crypto/des/set_key.c */
/* Copyright (C) 1995-1997 Eric Young ([e-mail])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([e-mail]).
 * 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 ([e-mail]).
 * 
 * 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 ([e-mail])"
 *    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 ([e-mail])"
 * 
 * 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.]
 */

/* set_key.c v 1.4 eay 24/9/91
 * 1.4 Speed up by 400% :-)
 * 1.3 added register declarations.
 * 1.2 unrolled make_key_sched a bit more
 * 1.1 added norm_expand_bits
 * 1.0 First working version
 */
#include "des/des_locl.h"
#include "des/podd.h"
#include "des/sk.h"

#ifndef NOPROTO
static int check_parity(des_cblock (*key));
#else
static int check_parity();
#endif

int des_check_key=0;

void des_set_odd_parity(key)
des_cblock (*key);
	{
	int i;

	for (i=0; i<DES_KEY_SZ; i++)
		(*key)[i]=odd_parity[(*key)[i]];
	}

static int check_parity(key)
des_cblock (*key);
	{
	int i;

	for (i=0; i<DES_KEY_SZ; i++)
		{
		if ((*key)[i] != odd_parity[(*key)[i]])
			return(0);
		}
	return(1);
	}

/* Weak and semi week keys as take from
 * %A D.W. Davies
 * %A W.L. Price
 * %T Security for Computer Networks
 * %I John Wiley & Sons
 * %D 1984
 * Many thanks to [e-mail] (Steven Bellovin) for the reference
 * (and actual cblock values).
 */
#define NUM_WEAK_KEY	16
static des_cblock weak_keys[NUM_WEAK_KEY]={
	/* weak keys */
	{0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01},
	{0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE},
	{0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,0x1F},
	{0xE0,0xE0,0xE0,0xE0,0xE0,0xE0,0xE0,0xE0},
	/* semi-weak keys */
	{0x01,0xFE,0x01,0xFE,0x01,0xFE,0x01,0xFE},
	{0xFE,0x01,0xFE,0x01,0xFE,0x01,0xFE,0x01},
	{0x1F,0xE0,0x1F,0xE0,0x0E,0xF1,0x0E,0xF1},
	{0xE0,0x1F,0xE0,0x1F,0xF1,0x0E,0xF1,0x0E},
	{0x01,0xE0,0x01,0xE0,0x01,0xF1,0x01,0xF1},
	{0xE0,0x01,0xE0,0x01,0xF1,0x01,0xF1,0x01},
	{0x1F,0xFE,0x1F,0xFE,0x0E,0xFE,0x0E,0xFE},
	{0xFE,0x1F,0xFE,0x1F,0xFE,0x0E,0xFE,0x0E},
	{0x01,0x1F,0x01,0x1F,0x01,0x0E,0x01,0x0E},
	{0x1F,0x01,0x1F,0x01,0x0E,0x01,0x0E,0x01},
	{0xE0,0xFE,0xE0,0xFE,0xF1,0xFE,0xF1,0xFE},
	{0xFE,0xE0,0xFE,0xE0,0xFE,0xF1,0xFE,0xF1}};

int des_is_weak_key(key)
des_cblock (*key);
	{
	int i;

	for (i=0; i<NUM_WEAK_KEY; i++)
		/* Added == 0 to comparision, I obviously don't run
		 * this section very often :-(, thanks to
		 * [e-mail] for the fix
		 * eay 93/06/29
		 * Another problem, I was comparing only the first 4
		 * bytes, 97/03/18 */
		if (memcmp(weak_keys[i],key,sizeof(des_cblock)) == 0) return(1);
	return(0);
	}

/* NOW DEFINED IN des_local.h
 * See ecb_encrypt.c for a pseudo description of these macros. 
 * #define PERM_OP(a,b,t,n,m) ((t)=((((a)>>(n))^(b))&(m)),\
 * 	(b)^=(t),\
 * 	(a)=((a)^((t)<<(n))))
 */

#define HPERM_OP(a,t,n,m) ((t)=((((a)<<(16-(n)))^(a))&(m)),\
	(a)=(a)^(t)^(t>>(16-(n))))

/* return 0 if key parity is odd (correct),
 * return -1 if key parity error,
 * return -2 if illegal weak key.
 */
int des_set_key(key, schedule)
des_cblock (*key);
des_key_schedule schedule;
	{
	static int shifts2[16]={0,0,1,1,1,1,1,1,0,1,1,1,1,1,1,0};
	register DES_LONG c,d,t,s,t2;
	register unsigned char *in;
	register DES_LONG *k;
	register int i;

	if (des_check_key)
		{
		if (!check_parity(key))
			return(-1);

		if (des_is_weak_key(key))
			return(-2);
		}

	k=(DES_LONG *)schedule;
	in=(unsigned char *)key;

	c2l(in,c);
	c2l(in,d);

	/* do PC1 in 60 simple operations */ 
/*	PERM_OP(d,c,t,4,0x0f0f0f0fL);
	HPERM_OP(c,t,-2, 0xcccc0000L);
	HPERM_OP(c,t,-1, 0xaaaa0000L);
	HPERM_OP(c,t, 8, 0x00ff0000L);
	HPERM_OP(c,t,-1, 0xaaaa0000L);
	HPERM_OP(d,t,-8, 0xff000000L);
	HPERM_OP(d,t, 8, 0x00ff0000L);
	HPERM_OP(d,t, 2, 0x33330000L);
	d=((d&0x00aa00aaL)<<7L)|((d&0x55005500L)>>7L)|(d&0xaa55aa55L);
	d=(d>>8)|((c&0xf0000000L)>>4);
	c&=0x0fffffffL; */

	/* I now do it in 47 simple operations :-)
	 * Thanks to John Fletcher ([e-mail])
	 * for the inspiration. :-) */
	PERM_OP (d,c,t,4,0x0f0f0f0fL);
	HPERM_OP(c,t,-2,0xcccc0000L);
	HPERM_OP(d,t,-2,0xcccc0000L);
	PERM_OP (d,c,t,1,0x55555555L);
	PERM_OP (c,d,t,8,0x00ff00ffL);
	PERM_OP (d,c,t,1,0x55555555L);
	d=	(((d&0x000000ffL)<<16L)| (d&0x0000ff00L)     |
		 ((d&0x00ff0000L)>>16L)|((c&0xf0000000L)>>4L));
	c&=0x0fffffffL;

	for (i=0; i<ITERATIONS; i++)
		{
		if (shifts2[i])
			{ c=((c>>2L)|(c<<26L)); d=((d>>2L)|(d<<26L)); }
		else
			{ c=((c>>1L)|(c<<27L)); d=((d>>1L)|(d<<27L)); }
		c&=0x0fffffffL;
		d&=0x0fffffffL;
		/* could be a few less shifts but I am to lazy at this
		 * point in time to investigate */
		s=	des_skb[0][ (c    )&0x3f                ]|
			des_skb[1][((c>> 6)&0x03)|((c>> 7L)&0x3c)]|
			des_skb[2][((c>>13)&0x0f)|((c>>14L)&0x30)]|
			des_skb[3][((c>>20)&0x01)|((c>>21L)&0x06) |
						  ((c>>22L)&0x38)];
		t=	des_skb[4][ (d    )&0x3f                ]|
			des_skb[5][((d>> 7L)&0x03)|((d>> 8L)&0x3c)]|
			des_skb[6][ (d>>15L)&0x3f                ]|
			des_skb[7][((d>>21L)&0x0f)|((d>>22L)&0x30)];

		/* table contained 0213 4657 */
		t2=((t<<16L)|(s&0x0000ffffL))&0xffffffffL;
		*(k++)=ROTATE(t2,30)&0xffffffffL;

		t2=((s>>16L)|(t&0xffff0000L));
		*(k++)=ROTATE(t2,26)&0xffffffffL;
		}
	return(0);
	}

int des_key_sched(key, schedule)
des_cblock (*key);
des_key_schedule schedule;
	{
	return(des_set_key(key,schedule));
	}