Zabbix

<?php declare(strict_types = 0);

/*

** Copyright (C) 2001-2025 Zabbix SIA

**

** This program is free software: you can redistribute it and/or modify it under the terms of

** the GNU Affero General Public License as published by the Free Software Foundation, version 3.

**

** This program 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 Affero General Public License for more details.

**

** You should have received a copy of the GNU Affero General Public License along with this program.

** If not, see <https://www.gnu.org/licenses/>.

**/

​

​

/**

 * Helper class for sign / encrypt data.

 */

class CEncryptHelper {

​

    /**

     * Signature algorithm.

     */

    public const SIGN_ALGO = 'sha256';

​

    /**

     * Session secret key.

     *

     * @var string

     */

    private static $key;

​

    /**

     * Return session key.

     *

     * @return string|null

     */

    private static function getKey(): ?string {

        if (!self::$key) {

            // This if contain copy in CEncryptedCookieSession class.

            if (CSettingsHelper::getPrivate(CSettingsHelper::SESSION_KEY) === '') {

                self::$key = self::generateKey();

​

                if (!self::updateKey(self::$key)) {

                    return null;

                }

​

                return self::$key;

            }

​

            self::$key = CSettingsHelper::getPrivate(CSettingsHelper::SESSION_KEY);

        }

​

        return self::$key;

    }

​

    /**

     * Timing attack safe string comparison.

     *

     * @param string $known_string

     * @param string $user_string

     *