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<?php declare(strict_types = 0);
/*
** Zabbix
** Copyright (C) 2001-2023 Zabbix SIA
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** 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 General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
**/
/**
* 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::getGlobal(CSettingsHelper::SESSION_KEY) === '') {
self::$key = self::generateKey();
if (!self::updateKey(self::$key)) {
return null;
}
return self::$key;
}
self::$key = CSettingsHelper::getGlobal(CSettingsHelper::SESSION_KEY);
}
return self::$key;
}
/**
* Timing attack safe string comparison.
*
* @param string $known_string
* @param string $user_string
*
* @return boolean
*/
public static function checkSign(string $known_string, string $user_string): bool {
return hash_equals($known_string, $user_string);
}
/**
* Encrypt string with session key.
*
* @param string $data
*
* @return string
*/
public static function sign(string $data): string {
$key = self::getKey();
return hash_hmac(self::SIGN_ALGO, $data, $key, false);
}
/**
* Generate random 16 bytes key.
*
* @return string
*/
public static function generateKey(): string {
return bin2hex(openssl_random_pseudo_bytes(16));
}
/**
* Update secret session key.
*
* @param string $key
*
* @return boolean
*/
public static function updateKey(string $key): bool {
$db_config = DB::select('config', ['output' => ['configid']])[0];
return DBexecute(
'UPDATE config'.
' SET session_key='.zbx_dbstr($key).
' WHERE '.dbConditionInt('configid', [$db_config['configid']])
);
}
}
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