My goal wasn't to create a 100% secure diary. If you need that, you probably should not store your data in the cloud. That's unlikely that I will ever try to make it happen. But even if I would, there're so many ways to screw it over anyway, so I won't ever try to make this promise.
However, I will consider open-sourcing it.
Also see my comment where I addressed the privacy issue: https://news.ycombinator.com/item?id=22045670