/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */

/* lib/crypto/krb/prf_cmac.c - CMAC-based PRF */

/*

 * Copyright (C) 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"

krb5_error_code

krb5int_dk_cmac_prf(const struct krb5_keytypes *ktp, krb5_key key,

                    const krb5_data *in, krb5_data *out)

{

    krb5_crypto_iov iov;

    krb5_data prfconst = make_data("prf", 3);

    krb5_key kp = NULL;

    krb5_error_code ret;

    if (ktp->prf_length != ktp->enc->block_size)

        return KRB5_BAD_MSIZE;

    iov.flags = KRB5_CRYPTO_TYPE_DATA;

    iov.data = *in;

    /* Derive a key using the PRF constant. */

    ret = krb5int_derive_key(ktp->enc, NULL, key, &kp, &prfconst,

                             DERIVE_SP800_108_CMAC);

    if (ret != 0)

        goto cleanup;

    /* PRF is CMAC of input */

    ret = krb5int_cmac_checksum(ktp->enc, kp, &iov, 1, out);

    if (ret != 0)

        goto cleanup;

cleanup:

    krb5_k_free_key(NULL, kp);

    return ret;

}