private function salted($key, $suffix = null)
    {
        $delimiter = ':';
        if (defined('static::DELIMITER')) {
            $delimiter = static::DELIMITER;
        }

        if (defined('static::PREFIX')) {
            $key = sprintf('%s%s%s', static::PREFIX, $delimiter, $key);
        }

        if ($suffix) {
            return sprintf('%s%s%s', $key, $delimiter, $suffix);
        }

        return $key;
    }