Several months ago, I read about someone who was making a key that was difficult if not "impossible" to copy. They mixed sparkly things into a plastic resin and let them set. A camera would take a picture

This boils down to difficulty of faking the analog interface. Anything that regular camera captures the attacker can also capture and reproduce it for the benefit of the camera. This means that camera has to be able to distinguish between the real thing and images of the real thing. This probably means going beyond optical image and somehow detecting 3D coordinates of particles, forcing the attacker to actually construct a new physical key carrier. At the current level of technology and economy, it's cheaper to hire an unemployed hardware engineer (no, s/w engs are not qualified,) to look at the key than to construct a 3D particle-sensing camera. ===== end (of original message) Y-a*h*o-o (yes, they scan for this) spam follows: __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com

In message <20030902233422.81119.qmail@web40609.mail.yahoo.com>, Morlock Elloi <morlockelloi@yahoo.com> wrote:

Anything that regular camera captures the attacker can also capture and reproduce it for the benefit of the camera.

Please read the paper. What's sent is not a picture of the token, but a hash of a picture of the pattern produced by a laser shining through the token. Because the laser scatters through the token in three dimensions it is difficult to model or reproduce the token. By varying the angle of the laser you can produce a large number of possible patterns, too many to be stored -- it's claimed this can be as much as 7 TB of data. So you can have a useful level of security even with untrusted token readers, and an extremely high level of security with trusted token readers. -- Shields.