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/*
* $Source$
* $Author$
*
* Copyright 1985, 1986, 1987, 1988, 1990 by the Massachusetts Institute
* of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
*
* These routines perform encryption and decryption using the DES
* private key algorithm, or else a subset of it-- fewer inner loops.
* (AUTH_DES_ITER defaults to 16, may be less.)
*
* Under U.S. law, this software may not be exported outside the US
* without license from the U.S. Commerce department.
*
* These routines form the library interface to the DES facilities.
*
* spm 8/85 MIT project athena
*/
#if !defined(lint) && !defined(SABER)
static char rcsid_cksum_c[] =
"$Id$";
#endif /* !lint & !SABER */
#include <krb5/krb5.h>
#include <krb5/ext-proto.h>
#include "des_int.h"
extern int mit_des_debug;
/*
* This routine performs DES cipher-block-chaining checksum operation,
* a.k.a. Message Authentication Code. It ALWAYS encrypts from input
* to a single 64 bit output MAC checksum.
*
* The key schedule is passed as an arg, as well as the cleartext or
* ciphertext. The cleartext and ciphertext should be in host order.
*
* NOTE-- the output is ALWAYS 8 bytes long. If not enough space was
* provided, your program will get trashed.
*
* The input is null padded, at the end (highest addr), to an integral
* multiple of eight bytes.
*/
void
mit_des_cbc_cksum(in,out,length,key,iv)
krb5_octet *in; /* >= length bytes of inputtext */
krb5_octet *out; /* >= length bytes of outputtext */
register long length; /* in bytes */
mit_des_key_schedule key; /* precomputed key schedule */
krb5_octet *iv; /* 8 bytes of ivec */
{
register unsigned long *input = (unsigned long *) in;
register unsigned long *output = (unsigned long *) out;
unsigned long *ivec = (unsigned long *) iv;
unsigned long i,j;
unsigned long t_input[2];
unsigned long t_output[8];
unsigned char *t_in_p;
t_in_p = (unsigned char *) t_input;
#ifdef MUSTALIGN
if ((long) ivec & 3) {
memcpy((char *)&t_output[0],(char *)ivec++,sizeof(t_output[0]));
memcpy((char *)&t_output[1],(char *)ivec,sizeof(t_output[1]));
}
else
#endif
{
t_output[0] = *ivec++;
t_output[1] = *ivec;
}
for (i = 0; length > 0; i++, length -= 8) {
/* get input */
#ifdef MUSTALIGN
if ((long) input & 3) {
memcpy((char *)&t_input[0],(char *)input++,sizeof(t_input[0]));
memcpy((char *)&t_input[1],(char *)input++,sizeof(t_input[1]));
}
else
#endif
{
t_input[0] = *input++;
t_input[1] = *input++;
}
/* zero pad */
if (length < 8)
for (j = length; j <= 7; j++)
*(t_in_p+j)= 0;
#ifdef DEBUG
if (mit_des_debug)
mit_des_debug_print("clear",length,t_input[0],t_input[1]);
#endif
/* do the xor for cbc into the temp */
t_input[0] ^= t_output[0] ;
t_input[1] ^= t_output[1] ;
/* encrypt */
(void) mit_des_ecb_encrypt(t_input,t_output,key,1);
#ifdef DEBUG
if (mit_des_debug) {
mit_des_debug_print("xor'ed",i,t_input[0],t_input[1]);
mit_des_debug_print("cipher",i,t_output[0],t_output[1]);
}
#else
#ifdef lint
i = i;
#endif
#endif
}
/* copy temp output and save it for checksum */
#ifdef MUSTALIGN
if ((long) output & 3) {
memcpy((char *)output++,(char *)&t_output[0],sizeof(t_output[0]));
memcpy((char *)output,(char *)&t_output[1],sizeof(t_output[1]));
}
else
#endif
{
*output++ = t_output[0];
*output = t_output[1];
}
return;
}
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