PMA\libraries\plugins\auth\AuthenticationCookie::_getSessionEncryptionSecret PHP Method

    private function _getSessionEncryptionSecret()
    {
        if (empty($_SESSION['encryption_key'])) {
            if (self::useOpenSSL()) {
                $_SESSION['encryption_key'] = openssl_random_pseudo_bytes(32);
            } else {
                $_SESSION['encryption_key'] = Crypt\Random::string(32);
            }
        }
        return $_SESSION['encryption_key'];
    }