Earlier quoted context omitted.
Amazon also quite clearly keeps hashes of all keys in S3, which Dropbox rides on. Would you expect the government to be able to issue hash based takedowns to amazon across all buckets? I was under the impression that Dropbox, while having the ability to decrypt your files, encrypts them before they hit S3. If so, a hash-based takedown sent to Amazon would at best be able to take down a single encrypted instance of a…
Except that Dropbox dedupe _everything_. So I suspect what happens is that everybodies bittorrented dvd rip of Avatar on dropbox is deduped and stored once on S3, admittedly encrypted, but all with Dropboxes encryption key and all with the same hash pointing at the same single encrypted instance of the file.
This makes things extra problematic because completely unrelated files might share chunks. Standard file formats may lead to duplicate headers. Or consider a political science textbook that contains a complete copy of the US Constitution, and a file that contains just the US Constitution. One is perfectly legal to distribute freely, the other may not be, but both might share some common blocks, and a federal judge with a shoot-first mentality might craft an order requiring the deletion of those common blocks.