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/*
* Copyright (c) 1990 Dennis Ferguson. All rights reserved.
*
* Commercial use is permitted only if products which are derived from
* or include this software are made available for purchase and/or use
* in Canada. Otherwise, redistribution and use in source and binary
* forms are permitted.
*/
/*
* des_cbc_cksum.c - compute an 8 byte checksum using DES in CBC mode
*/
#include "des.h"
#include "f_tables.h"
unsigned long
des_cbc_cksum(in, out, length, schedule, ivec)
des_cblock *in;
des_cblock *out;
long length;
des_key_schedule schedule;
des_cblock ivec;
{
register unsigned long left, right;
register unsigned long temp;
register u_int32 *kp;
register unsigned char *ip;
register long len;
/*
* Initialize left and right with the contents of the initial
* vector.
*/
ip = (unsigned char *)ivec;
GET_HALF_BLOCK(left, ip);
GET_HALF_BLOCK(right, ip);
/*
* Suitably initialized, now work the length down 8 bytes
* at a time.
*/
ip = (unsigned char *)in;
len = length;
while (len > 0) {
/*
* Get more input, xor it in. If the length is
* greater than or equal to 8 this is straight
* forward. Otherwise we have to fart around.
*/
if (len >= 8) {
left ^= ((*ip++) & 0xff) << 24;
left ^= ((*ip++) & 0xff) << 16;
left ^= ((*ip++) & 0xff) << 8;
left ^= (*ip++) & 0xff;
right ^= ((*ip++) & 0xff) << 24;
right ^= ((*ip++) & 0xff) << 16;
right ^= ((*ip++) & 0xff) << 8;
right ^= (*ip++) & 0xff;
len -= 8;
} else {
/*
* Oh, shoot. We need to pad the
* end with zeroes. Work backwards
* to do this.
*/
ip += (int) len;
switch(len) {
case 7:
right ^= (*(--ip) & 0xff) << 8;
case 6:
right ^= (*(--ip) & 0xff) << 16;
case 5:
right ^= (*(--ip) & 0xff) << 24;
case 4:
left ^= *(--ip) & 0xff;
case 3:
left ^= (*(--ip) & 0xff) << 8;
case 2:
left ^= (*(--ip) & 0xff) << 16;
case 1:
left ^= (*(--ip) & 0xff) << 24;
break;
}
len = 0;
}
/*
* Encrypt what we have
*/
kp = (u_int32 *)schedule;
DES_DO_ENCRYPT(left, right, temp, kp);
}
/*
* Done. Left and right have the checksum. Put it into
* the output.
*/
ip = (unsigned char *)out;
PUT_HALF_BLOCK(left, ip);
PUT_HALF_BLOCK(right, ip);
/*
* Return right. I'll bet the MIT code returns this
* inconsistantly (with the low order byte of the checksum
* not always in the low order byte of the long). We won't.
*/
return right;
}
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