/*

 * Copyright (C) 2017 Red Hat, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include "datum.h"

#include "global.h"

#include "errors.h"

#include "common.h"

#include "x509.h"

#include "x509_int.h"

#include "mpi.h"

#include "prov-seed.h"

/* This function encodes a seed value and a hash algorithm OID to the format

 * described in RFC8479. The output is the DER encoded form.

 */

int _x509_encode_provable_seed(gnutls_x509_privkey_t pkey, gnutls_datum_t *der)

{

  asn1_node c2;

  int ret, result;

  const char *oid;

  oid = gnutls_digest_get_oid(pkey->params.palgo);

  if (oid == NULL)

    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  if ((result = asn1_create_element(_gnutls_get_gnutls_asn(),

            "GNUTLS.ProvableSeed", &c2)) !=

      ASN1_SUCCESS) {

    gnutls_assert();

    return _gnutls_asn2err(result);

  }

  result = asn1_write_value(c2, "seed", pkey->params.seed,

          pkey->params.seed_size);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  result = asn1_write_value(c2, "algorithm", oid, 1);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  ret = _gnutls_x509_der_encode(c2, "", der, 0);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = 0;

cleanup:

  asn1_delete_structure2(&c2, ASN1_DELETE_FLAG_ZEROIZE);

  return ret;

}

/* This function decodes a DER encoded form of seed and a hash algorithm, as in

 * RFC8479.

 */

int _x509_decode_provable_seed(gnutls_x509_privkey_t pkey,

             const gnutls_datum_t *der)

{

  asn1_node c2;

  int ret, result;

  char oid[MAX_OID_SIZE];

  int oid_size;

  gnutls_datum_t seed = { NULL, 0 };

  if ((result = asn1_create_element(_gnutls_get_gnutls_asn(),

            "GNUTLS.ProvableSeed", &c2)) !=

      ASN1_SUCCESS) {

    gnutls_assert();

    return _gnutls_asn2err(result);

  }

  result = _asn1_strict_der_decode(&c2, der->data, der->size, NULL);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  ret = _gnutls_x509_read_value(c2, "seed", &seed);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  if (seed.size <= sizeof(pkey->params.seed)) {

    memcpy(pkey->params.seed, seed.data, seed.size);

    pkey->params.seed_size = seed.size;

  } else {

    ret = 0; /* ignore struct */

    _gnutls_debug_log(

      "%s: ignoring ProvableSeed due to very long params\n",

      __func__);

    goto cleanup;

  }

  oid_size = sizeof(oid);

  result = asn1_read_value(c2, "algorithm", oid, &oid_size);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  pkey->params.palgo = gnutls_oid_to_digest(oid);

  pkey->params.pkflags |= GNUTLS_PK_FLAG_PROVABLE;

  ret = 0;

cleanup:

  gnutls_free(seed.data);

  asn1_delete_structure2(&c2, ASN1_DELETE_FLAG_ZEROIZE);

  return ret;

}