cbc_enc.c

Netscape公司提供的安全套接字层

/* 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);
    }