Even if all data is encrypted at rest, you can still learn a huge amount from access patterns. You need some kind of Oblivious RAM (which could perhaps be bette

Even if all data is encrypted at rest, you can still learn a huge amount from access patterns. You need some kind of Oblivious RAM (which could perhaps be better named Oblivious Disk) where the cloud server doesn't even know the metadata (e.g. which disk sector) it's serving, let alone the content. Cryptographers know how to do this in theory, but the overhead is pretty big.