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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* lib/crypto/krb/prf/dk_prf.c
*
* Copyright (C) 2004 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.
*
*
*
* This file contains an implementation of the RFC 3961 PRF for
*simplified profile enctypes.
*/
#include "prf_int.h"
#include <dk.h>
krb5_error_code
krb5int_dk_prf(const struct krb5_keytypes *ktp, krb5_key key,
const krb5_data *in, krb5_data *out)
{
const struct krb5_enc_provider *enc = ktp->enc;
const struct krb5_hash_provider *hash = ktp->hash;
krb5_crypto_iov iov;
krb5_data prfconst = make_data("prf", 3);
krb5_key kp = NULL;
krb5_error_code ret;
/* Hash the input data into an allocated buffer. */
iov.flags = KRB5_CRYPTO_TYPE_DATA;
ret = alloc_data(&iov.data, hash->hashsize);
if (ret != 0)
return ret;
ret = hash->hash(1, in, &iov.data);
if (ret != 0)
goto cleanup;
/* Truncate the hash to the closest multiple of the block size. */
iov.data.length = (iov.data.length / enc->block_size) * enc->block_size;
/* Derive a key using the PRF constant. */
ret = krb5int_derive_key(ktp->enc, key, &kp, &prfconst);
if (ret != 0)
goto cleanup;
/* Encrypt the truncated hash in the derived key to get the output. */
ret = ktp->enc->encrypt(kp, NULL, &iov, 1);
if (ret != 0)
goto cleanup;
memcpy(out->data, iov.data.data, out->length);
cleanup:
zapfree(iov.data.data, hash->hashsize);
krb5_k_free_key(NULL, kp);
return ret;
}
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