
http://news.bbc.co.uk/1/hi/technology/6312833.stm
(so that's where all the money went into!)Each graphics card manufacturer is responsible for specifying the actual authentication tests, because only they know the subtle idiosyncrasies of their chip. Such tests could involve loading a surface with an image, and then getting the chip to apply various visual effects to the image and reporting back the resulting pixels. Each chip design will return a subtly different set of pixels as the answer.
http://www.microsoft.com/whdc/device/st ... otect.mspx