[jodrellblank]

I was assuming dropbox would do reference counting so they could delete data that nobody is using, and account tracking so they can put storage limits on your account and charge you for using more space.

But they could make a system which didn't do those things and then they would be able to do as you discuss.

Now the limit to what they could do for the RIAA is identify if they have a file stored and delete it or block it from being stored, but only with an example whole file - not by filename or hash.

So the solution is ugly, and reasonable, but has some weaknesses. Yet, it is better than nothing.

Maybe. It depends what you are guarding against. If you fundamentally do not trust dropbox, then it is no better than nothing. If you do want to keep copied music files then it is pretty much no better than nothing. If you want convenience and features it is worse than nothing. If you want a basic security that stops dropbox easily trawling your most personal files, it is better than nothing.

[bdhe]

I was assuming dropbox would do reference counting so they could delete data that nobody is using, and account tracking so they can put storage limits on your account and charge you for using more space.

Definitely. There are a few problems that can "de-anonymize" users. I don't claim that the outline presented would be very robust.

Maybe. It depends what you are guarding against.

I agree, that requires more qualification. I think in the context of subpoenas or trawling, there are some definite advantages.