/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/crypto/krb/checksum_dk_cmac.c */
/*
* Copyright 2010 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. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* 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.
*/
#include "crypto_int.h"
#define K5CLENGTH 5 /* 32 bit net byte order integer + one byte seed */
krb5_error_code
krb5int_dk_cmac_checksum(const struct krb5_cksumtypes *ctp,
krb5_key key, krb5_keyusage usage,
const krb5_crypto_iov *data, size_t num_data,
krb5_data *output)
{
const struct krb5_enc_provider *enc = ctp->enc;
krb5_error_code ret;
unsigned char constantdata[K5CLENGTH];
krb5_data datain;
krb5_key kc;
/* Derive the key. */
datain = make_data(constantdata, K5CLENGTH);
store_32_be(usage, constantdata);
constantdata[4] = (char) 0x99;
ret = krb5int_derive_key(enc, NULL, key, &kc, &datain,
DERIVE_SP800_108_CMAC);
if (ret != 0)
return ret;
/* Hash the data. */
ret = krb5int_cmac_checksum(enc, kc, data, num_data, output);
if (ret != 0)
memset(output->data, 0, output->length);
krb5_k_free_key(NULL, kc);
return ret;
}