@fubaroque

The retinal scanners seen in Half-Life would probably still hold up as an authentication mechanism. The scanners aren't under attacker control, and there's no apparent way for an attacker to tamper with the scanner or input a forged biometric (i.e. hold a printout of retinas in front of the scanner instead of your actual eyes) without tipping off the nearby security guard.

But yeah, those are the lengths you've got to go to, to make biometric authentication secure.

@todb