Well, the technology may not be there yet, but conceptually, the strongest authentication available is some combination of voice and face recognition, as done by a human.
If you consider just a camera (with no additional sensors spread over a large area), it is a crappy concept. Its the kind of concept that stops being viable once it starts being possible.
Only an awesome 3D camera with an extremely wide angle would not fall into the "just use a printed piece of paper" method. And that non-existent awesome camera would still fall for several other methods, such as well-built models of your face. Even if you're using awesome stereo vision from 2010, the same printed piece of paper in front of any cheap model of a human head will do.
And the kind of AI needed for a computer to detect a person using only image and sound is HARD. So hard that when we actually have this kind of AI, the cheap tech needed to fool it (the hell, to fool real people) will already be available.
eg, if you want a new passport, in England, you have to take a picture, and get someone you know to certify it's a true likeness of you. How does that person know it is you? Well, by seeing how you look like, and listening to your voice. I guess?
The picture allows humans to recognise you. It is meant for humans and humans only.
So, from a theoretical point of view, this system is I feel sound. Just, maybe the technology is not quite there yet
It depends. If you can afford distributing sensors all over the place, it is POSSIBLE to avoid cheating. You can add cameras and distance sensors over a large area and youll stop most forms of cheating. High-tech cheaters can get away by standing in front of the system and using a special set-up to project a different image inside the camera.
If all you want is a small sensor embedded on a laptop computer, its a stupid concept.