I have an alternate explanation: It's easier this way. I'm not attempting to downplay Dropbox's (or anyone else's) efforts, but Crypto Is Hard. Really Hard. Onc

I have an alternate explanation: It's easier this way. I'm not attempting to downplay Dropbox's (or anyone else's) efforts, but Crypto Is Hard. Really Hard. Once you try to implement zero-knowledge full encryption, it gets Really Freaking Ridiculously Hard, some cool things stop even being possible (Web access? Sorry, no can do.), and it becomes easy to fail while appearing to work (see e.g. http://www.cryptofails.com/2013/07/synergy-integer-overflow-key-reuse-iv.html http://www.cryptofails.com/2013/07/synergy-integer-overflow-... ). Also, there isn't (yet) a mass demand for such features, and there are smaller providers offering those.