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<?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
*
* @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);
}
/**
* 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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