cbc_enc.c

基于DSP的用C语言实现语音编码解码

/* lib/des/cbc_enc.c */
/* Copyright (C) 1995 Eric Young ([e-mail])
 * All rights reserved.
 * 
 * This file is part of an SSL implementation written
 * by Eric Young ([e-mail]).
 * The implementation was written so as to conform with Netscapes SSL
 * specification.  This library and applications are
 * FREE FOR COMMERCIAL AND NON-COMMERCIAL USE
 * as long as the following conditions are aheared to.
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.	If this code is used in a product,
 * Eric Young should be given attribution as the author of the parts 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 software developed by Eric Young ([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.]
 */

#include "des_locl.h"

void des_cbc_encrypt(input, output, length, schedule, ivec, encrypt)
des_cblock (*input);
des_cblock (*output);
long length;
des_key_schedule schedule;
des_cblock (*ivec);
int encrypt;
		{
		register unsigned long tin0,tin1;
		register unsigned long tout0,tout1,xor0,xor1;
		register unsigned char *in,*out;
		register long l=length;
		unsigned long tin[2];
		unsigned char *iv;

		in=(unsigned char *)input;
		out=(unsigned char *)output;
		iv=(unsigned char *)ivec;

		if (encrypt)
				{
				c2l(iv,tout0);
				c2l(iv,tout1);
				for (; l>0; l-=8)
						{
						if (l >= 8)
								{
								c2l(in,tin0);
								c2l(in,tin1);
								}
						else
								c2ln(in,tin0,tin1,l);
						tin0^=tout0; tin[0]=tin0;
						tin1^=tout1; tin[1]=tin1;
						des_encrypt((unsigned long *)tin,schedule,DES_ENCRYPT);
						tout0=tin[0]; l2c(tout0,out);
						tout1=tin[1]; l2c(tout1,out);
						}
				}
		else
				{
				c2l(iv,xor0);
				c2l(iv,xor1);
				for (; l>0; l-=8)
						{
						c2l(in,tin0); tin[0]=tin0;
						c2l(in,tin1); tin[1]=tin1;
						des_encrypt((unsigned long *)tin,schedule,DES_DECRYPT);
						tout0=tin[0]^xor0;
						tout1=tin[1]^xor1;
						if (l >= 8)
								{
								l2c(tout0,out);
								l2c(tout1,out);
								}
						else
								l2cn(tout0,tout1,out,l);
						xor0=tin0;
						xor1=tin1;
						}
				}
		tin0=tin1=tout0=tout1=xor0=xor1=0;
		tin[0]=tin[1]=0;
		}