protected function getEncryptionKeyByObjectNumber($objectNumber)
    {
        return substr(
            substr(
                md5($this->encryptionKey . pack('VXxx', $objectNumber), true),
                0,
                $this->keyLength + 5
            ),
            0,
            16
        );
    }
protected function getEncryptionKeyByObjectNumber($objectNumber)
    {
        return substr(
            substr(
                md5($this->encryptionKey . pack('VXxx', $objectNumber), true),
                0,
                $this->keyLength + 5
            ),
            0,
            16
        );
    }
protected function getEncryptionKeyByObjectNumber ( $ objectNumber ) { return substr ( substr ( md5 ( $ this -> encryptionKey . pack ( 'VXxx' , $ objectNumber ) , true ) , 0 , $ this -> keyLength + 5 ) , 0 , 16 ) ; }
Computes the encryption key by an object number

@param int $objectNumber
@return bool|string
Computes the encryption key by an object number