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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  /**
  17   * This file contains functions used by upgrade and install.
  18   *
  19   * Because this is used during install it should not include additional files.
  20   *
  21   * @package   enrol_lti
  22   * @copyright 2021 Jake Dallimore <jrhdallimore@gmail.com>
  23   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24   */
  25  
  26  defined('MOODLE_INTERNAL') || die();
  27  
  28  /**
  29   * This function checks if a private key has been generated for this enrolment instance.
  30   *
  31   * If the key does not exist it generates a new one. If the openssl
  32   * extension is not installed or configured properly it returns a warning message.
  33   *
  34   * @return string A warning message if a private key does not exist and cannot be generated.
  35   */
  36  function enrol_lti_verify_private_key() {
  37  
  38      $name = 'lti_13_kid';
  39      $key = get_config('enrol_lti', $name);
  40  
  41      // If we already generated a valid key, no need to check.
  42      if (empty($key)) {
  43          // Create the private key.
  44          $kid = bin2hex(openssl_random_pseudo_bytes(10));
  45          set_config($name, $kid, 'enrol_lti');
  46          $config = array(
  47              "digest_alg" => "sha256",
  48              "private_key_bits" => 2048,
  49              "private_key_type" => OPENSSL_KEYTYPE_RSA,
  50          );
  51          $res = openssl_pkey_new($config);
  52          openssl_pkey_export($res, $privatekey);
  53  
  54          if (!empty($privatekey)) {
  55              set_config('lti_13_privatekey', $privatekey, 'enrol_lti');
  56          } else {
  57              return get_string('opensslconfiginvalid', 'enrol_lti');
  58          }
  59      }
  60  
  61      return '';
  62  }