private function decode($encData)
    {
        $params = explode(self::ENC_SEPARATOR, $encData);
        if (count($params) < self::ENC_SECTIONS) {
            return false;
        }

        $startIndex = intval(base64_decode($params[self::ENC_STARTINDEX_INDEX]));
        $dataLength = intval(base64_decode($params[self::ENC_DATALENGTH_INDEX]));

        if (empty($startIndex) || empty($dataLength)) {
            return false;
        }

        $data = $params[self::ENC_DATA_INDEX];

        return base64_decode(substr($data, $startIndex, $dataLength));
    }