No, the Key isn't sent over SATA. It works like this if I understand it right:
DVD-Drive encrypt Data with DVD-Key => Send encrypted Data over SATA => Console decrypt this Data with DVD-Key.
DVD-Drive encrypt Data with DVD-Key => Send encrypted Data over SATA => Console decrypt this Data with DVD-Key.
If you send encrypted data and know the dvd-key and decrypt the data and then send the same encrypted data with the unknow key and compare it whit dectypt data to generate the key?.

