[tptacek]

If you've invented the most convenient file transfer tool on the whole Internet, you've buried the lede here; forget about the encryption, and get your Dropbox-competitor funded.

If you haven't, well, people should use that other service instead of this one.

Either way: I'm still totally unclear on why anyone would allow a server to encrypt files for them. I don't even reach the question of whether it's possible to do it securely, because it seems like such a weird thing to want.