cbc_enc.c

一个DES、3DES加解密的库文件

/* cbc_enc.c */
/* Copyright (C) 1993 Eric Young - see README for more details */
#include "des_locl.h"

int 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 tout[2],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;
			tin1^=tout1;
			tin[0]=tin0;
			tin[1]=tin1;
			des_encrypt((unsigned long *)tin,(unsigned long *)tout,
				schedule,encrypt);
			tout0=tout[0];
			tout1=tout[1];
			l2c(tout0,out);
			l2c(tout1,out);
			}
		}
	else
		{
		c2l(iv,xor0);
		c2l(iv,xor1);
		for (; l>0; l-=8)
			{
			c2l(in,tin0);
			c2l(in,tin1);
			tin[0]=tin0;
			tin[1]=tin1;
			des_encrypt((unsigned long *)tin,(unsigned long *)tout,
				schedule,encrypt);
			tout0=tout[0]^xor0;
			tout1=tout[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]=tout[0]=tout[1]=0;
	return(0);
	}