[yjftsjthsd-h]

> My understanding is Dropbox used to first hash file, then see if a copy was already uploaded. That was removed as it was being used for piracy.

How's that work? Somehow modify the client to say that you have a file with a user-provided hash even though it doesn't actually exist on disk?

[CJefferson]

Yes, that's exactly what people were doing -- then you could pirate a film by only distributing the hash.