I might be too late to jump in here, but here are my thoughts on TwoFactor authentication using "unique"* biometrics. If I scan my fingerprint in to authentica

I might be too late to jump in here, but here are my thoughts on TwoFactor authentication using "unique"* biometrics. If I scan my fingerprint in to authenticate or scan my retina, on a device that knows my physical location, that is a more literal check-in than anything that exists today. Essentially a check-in would have near absolute certainty that the actual person authenticating was at that place at that time. That's scary to me; one may have a GPS on their phone today, but that's the phones identity, not the owners. If one signs ones credit cards with a thumb print or a retina scan, one is proving beyond any shadow of a doubt that one was present at that place at that time. This may or may not be something one wants and one should be conscious of the realities of biometric authentication. *Just because no one has presented a copy of a retina that can pass a retina scan does not mean one does not exist.