> I don't see how we can avoid the "trusted" hardware requirement.

While this is a good point, what's missing here is that this hardware doesn't have to have Google spyware and other bloatware installed. Yet with current design, this becomes mandatory.. security requirements are abused here to force unrelated software on my computer that I have to carry with me in order to participate in society.

This app should work on a dedicated device, something like a smartcard with e-ink display.. it would even be more secure because it would have less attack surface. Just like today I'm not complaining about not being able to install linux on my credit/SIM card, I'd not complain about that either. But locking down the whole OS on my smartphone is unacceptable.