/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *   http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing,

 * software distributed under the License is distributed on an

 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 * KIND, either express or implied.  See the License for the

 * specific language governing permissions and limitations

 * under the License.

 */

/***************************************************************************

 * Copyright (C) 2017-2026 ZmartZone Holding BV

 * All rights reserved.

 *

 * DISCLAIMER OF WARRANTIES:

 *

 * THE SOFTWARE PROVIDED HEREUNDER IS PROVIDED ON AN "AS IS" BASIS, WITHOUT

 * ANY WARRANTIES OR REPRESENTATIONS EXPRESS, IMPLIED OR STATUTORY; INCLUDING,

 * WITHOUT LIMITATION, WARRANTIES OF QUALITY, PERFORMANCE, NONINFRINGEMENT,

 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  NOR ARE THERE ANY

 * WARRANTIES CREATED BY A COURSE OR DEALING, COURSE OF PERFORMANCE OR TRADE

 * USAGE.  FURTHERMORE, THERE ARE NO WARRANTIES THAT THE SOFTWARE WILL MEET

 * YOUR NEEDS OR BE FREE FROM ERRORS, OR THAT THE OPERATION OF THE SOFTWARE

 * WILL BE UNINTERRUPTED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * @Author: Hans Zandbelt - hans.zandbelt@openidc.com

 */

#include "util/util.h"

#include <openssl/evp.h>

/* iteration count for PBKDF2-HMAC-SHA256, per current OWASP guidance; this only runs once per

 * (re)start, in the single-threaded post_config phase -- see oidc_cfg_crypto_passphrase_post_config */

#define OIDC_UTIL_KEY_DERIVE_ITERATIONS 210000

/* fixed, non-secret, application-specific salt: it exists for domain separation (so a

 * precomputed table built against some other use of PBKDF2-HMAC-SHA256 does not apply here),

 * not to protect against an attacker who has the source code */

#define OIDC_UTIL_KEY_DERIVE_SALT "mod_auth_openidc-crypto-passphrase-v1"

/*

 * stretch an operator-supplied OIDCCryptoPassphrase value into "out_len" bytes of key material

 * using PBKDF2-HMAC-SHA256, so that a low-entropy passphrase cannot be brute-forced offline at

 * the speed of a single SHA-256 evaluation

 */

apr_byte_t oidc_util_key_derive_passphrase_key(const char *passphrase, unsigned char *out, apr_size_t out_len) {

  if ((passphrase == NULL) || (_oidc_strlen(passphrase) == 0))

    return FALSE;

  return (PKCS5_PBKDF2_HMAC(passphrase, (int)_oidc_strlen(passphrase),

          (const unsigned char *)OIDC_UTIL_KEY_DERIVE_SALT,

          (int)(sizeof(OIDC_UTIL_KEY_DERIVE_SALT) - 1), OIDC_UTIL_KEY_DERIVE_ITERATIONS,

          EVP_sha256(), (int)out_len, out) == 1)

       ? TRUE

       : FALSE;

}

/*

 * create a symmetric key from a client_secret

 */

apr_byte_t oidc_util_key_symmetric_create(request_rec *r, const char *client_secret, unsigned int r_key_len,

            const char *hash_algo, apr_byte_t set_kid, oidc_jwk_t **jwk) {

  oidc_jose_error_t err = {{'\0'}, 0, {'\0'}, {'\0'}};

  const unsigned char *key = NULL;

  unsigned int key_len;

  if ((client_secret != NULL) && (_oidc_strlen(client_secret) > 0)) {

    if (hash_algo == NULL) {

      key = (const unsigned char *)client_secret;

      key_len = (unsigned int)_oidc_strlen(client_secret);

    } else {

      /* hash the client_secret first, this is OpenID Connect specific */

      unsigned char *hashed = NULL;

      if (oidc_jose_hash_bytes(r->pool, hash_algo, (const unsigned char *)client_secret,

             (unsigned int)_oidc_strlen(client_secret), &hashed, &key_len,

             &err) == FALSE)

        return FALSE;

      key = hashed;

    }

    if ((key != NULL) && (key_len > 0)) {

      if ((r_key_len != 0) && (key_len >= r_key_len))

        key_len = r_key_len;

      *jwk = oidc_jwk_create_symmetric_key(r->pool, NULL, key, key_len, set_kid, &err);

    }

    if (*jwk == NULL) {

      oidc_error(r, "could not create JWK from the provided secret: %s", oidc_jose_e2s(r->pool, err));

      return FALSE;

    }

  }

  return TRUE;

}

/*

 * merge an array of JWKs and a JWK into a single hashtable

 */

apr_hash_t *oidc_util_key_symmetric_merge(apr_pool_t *pool, const apr_array_header_t *keys, const oidc_jwk_t *jwk) {

  apr_hash_t *result = apr_hash_make(pool);

  const oidc_jwk_t *elem = NULL;

  if (keys != NULL) {

    for (int i = 0; i < keys->nelts; i++) {

      elem = APR_ARRAY_IDX(keys, i, const oidc_jwk_t *);

      if (elem->kid != NULL)

        apr_hash_set(result, elem->kid, APR_HASH_KEY_STRING, elem);

    }

  }

  if (jwk != NULL) {

    apr_hash_set(result, jwk->kid, APR_HASH_KEY_STRING, jwk);

  }

  return result;

}

/*

 * merge the provided array of keys (k2) into a hash table of keys (k1)

 */

apr_hash_t *oidc_util_key_sets_merge(apr_pool_t *pool, apr_hash_t *k1, const apr_array_header_t *k2) {

  apr_hash_t *rv = k1 ? apr_hash_copy(pool, k1) : apr_hash_make(pool);

  const oidc_jwk_t *jwk = NULL;

  if (k2 != NULL) {

    for (int i = 0; i < k2->nelts; i++) {

      jwk = APR_ARRAY_IDX(k2, i, const oidc_jwk_t *);

      if (jwk->kid != NULL)

        apr_hash_set(rv, jwk->kid, APR_HASH_KEY_STRING, jwk);

    }

  }

  return rv;

}

/*

 * merge two hash tables with key sets

 */

apr_hash_t *oidc_util_key_sets_hash_merge(apr_pool_t *pool, apr_hash_t *k1, apr_hash_t *k2) {

  if (k1 == NULL) {

    if (k2 == NULL)

      return apr_hash_make(pool);

    return k2;

  }

  if (k2 == NULL)

    return k1;

  return apr_hash_overlay(pool, k1, k2);

}

/*

 * return the first JWK that matches a provided key type and use from an array of JWKs

 */

oidc_jwk_t *oidc_util_key_list_first(const apr_array_header_t *key_list, int kty, const char *use) {

  oidc_jwk_t *rv = NULL;

  oidc_jwk_t *jwk = NULL;

  for (int i = 0; key_list && (i < key_list->nelts); i++) {

    jwk = APR_ARRAY_IDX(key_list, i, oidc_jwk_t *);

    if ((kty != -1) && (jwk->kty != kty))

      continue;

    if ((use == NULL) || (jwk->use == NULL) || (_oidc_strncmp(jwk->use, use, _oidc_strlen(use)) == 0)) {

      rv = jwk;

      break;

    }

  }

  return rv;

}