Keeping it on the phone means that we don't need to re-generate a new one or transmit your old one when you change computers. You're absolutely right that keep

Keeping it on the phone means that we don't need to re-generate a new one or transmit your old one when you change computers. You're absolutely right that keeping the data safe on the phone is an important challenge and it's something we're working hard on. PIN-based encryption is the solution for now, but an invisible attack could be dangerous (though the attack's you mention through the USB key require a rooted phone with permissions allowed, which is not common- privilege escalation attacks are one vector which we still have to work against) We think what we have right now is a big improvement over the status quo, and that we still have a lot of room to keep getting better. Thanks for the feedback.