To my knowledge it is not. For this reason, I stopped using it, despite their otherwise very nice approach generally. I have been doing without cloud storage for my most important files (financial documents, etc.), so I'm pretty interested in Filerock, having found this thread.

I naively attempted to roll my own mash-up for this purpose (https://github.com/clebio/duplicitySync) and was not successful. The combination of local encryption, incremental backup, and _synchronization across multiple computers_ was the breaking point.