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/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* 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 FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "k5-int.h"
#include "etypes.h"
#include "dk.h"
#define K5CLENGTH 5 /* 32 bit net byte order integer + one byte seed */
krb5_error_code
krb5_dk_make_checksum(const struct krb5_hash_provider *hash,
const krb5_keyblock *key, krb5_keyusage usage,
const krb5_data *input, krb5_data *output)
{
int i;
const struct krb5_enc_provider *enc;
size_t blocksize, keybytes, keylength;
krb5_error_code ret;
unsigned char constantdata[K5CLENGTH];
krb5_data datain;
unsigned char *kcdata;
krb5_keyblock kc;
for (i=0; i<krb5_enctypes_length; i++) {
if (krb5_enctypes_list[i].etype == key->enctype)
break;
}
if (i == krb5_enctypes_length)
return(KRB5_BAD_ENCTYPE);
enc = krb5_enctypes_list[i].enc;
/* allocate and set to-be-derived keys */
blocksize = enc->block_size;
keybytes = enc->keybytes;
keylength = enc->keylength;
/* key->length will be tested in enc->encrypt
output->length will be tested in krb5_hmac */
if ((kcdata = (unsigned char *) malloc(keylength)) == NULL)
return(ENOMEM);
kc.contents = kcdata;
kc.length = keylength;
/* derive the key */
datain.data = (char *) constantdata;
datain.length = K5CLENGTH;
datain.data[0] = (usage>>24)&0xff;
datain.data[1] = (usage>>16)&0xff;
datain.data[2] = (usage>>8)&0xff;
datain.data[3] = usage&0xff;
datain.data[4] = (char) 0x99;
if ((ret = krb5_derive_key(enc, key, &kc, &datain)) != 0)
goto cleanup;
/* hash the data */
datain = *input;
if ((ret = krb5_hmac(hash, &kc, 1, &datain, output)) != 0)
memset(output->data, 0, output->length);
/* ret is set correctly by the prior call */
cleanup:
memset(kcdata, 0, keylength);
free(kcdata);
return(ret);
}
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