Crypto anarchy in a VW? (not the bug)

I argue that encrypted hard disks should be encrypted at the transfer level.

Actually I was sort of thinking of the keying being done on a per-user basis.

Never fear. Layered encryption is the way of the future. One layer of encryption for the disk as a whole, another for the users. When the stuff gets cheap enough, it will be everywhere. The question is "Who is your opponent?" If you are concerned with the users against each other, then use user level encryption. If you are concerned with the outside world against the machine, then encrypt at the disk controller or device driver level. If you are concerned about both, then do both. Eric