Full private document editing

Currently, there's no(or atleast none that I can find) platforms that offer fully private document editing. Today if I want to create a personal journal or jot down ideas, I'd likely have to expose it to a company like google which will scan to feed their advertising services or a company with less liability costs for unscrupulous behavior. I think this fits well with one of the core aspects of Kin, which is the ability to create a private reflection of one own's identity. So instead of considering it as a side product, it might be best to consider if this has synergistic properties to support the primary product direction.\