cbc_cksm.c

来自「Netscape公司提供的安全套接字层」· C语言 代码 · 共 51 行

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

unsigned long des_cbc_cksum(input,output,length,schedule,ivec)
des_cblock *input;
des_cblock *output;
long length;
des_key_schedule schedule;
des_cblock *ivec;
    {
    register unsigned long tout0,tout1,tin0,tin1;
    register long l=length;
    unsigned long tin[2],tout[2];
    unsigned char *in,*out,*iv;

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

    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,DES_ENCRYPT);
        /* fix 15/10/91 eay - thanks to [e-mail] */
        tout0=tout[0];
        tout1=tout[1];
        }
    if (out != NULL)
        {
        l2c(tout0,out);
        l2c(tout1,out);
        }
    tout0=tin0=tin1=tin[0]=tin[1]=tout[0]=tout[1]=0;
    return(tout1);
    }