To expand on that, mega.co.nz does attempt to do encryption end deduplication. Each file uploaded is encrypted with it's own hash, and the hash is stored in the

To expand on that, mega.co.nz does attempt to do encryption end deduplication. Each file uploaded is encrypted with it's own hash, and the hash is stored in the users encrypted account. The idea is that if two users upload the same file they will have the same hash and be deduplicated. It's not particularly secure or private in their implementation, but it can certainly be done.