In the midst of all the news about Kim Dotcom's Mega, I started wondering: do any online backup solutions actually store your information encrypted in such a way that they cannot decrypt it?
All of them advertise SSL encryption over the wire and then on-disk encryption at the data-centers, but I have a hard time determining from their marketing literature whether they actually keep a copy of the keys to decrypt the data.
Most (all?) solutions like Backblaze and Mozy install an agent on your machine which takes care of sending your data to the backup server. It's easy to imagine an agent that generates the key locally and encrypts the files before they're sent such that the service does not actually know the key, but do any of the services do this?