unforgeable optical tokens?

[David Honig]

At 12:07 PM 9/20/02 -0400, Perry E. Metzger wrote:
>
>A couple of places have reported on this:
>
>http://www.nature.com/nsu/020916/020916-15.html
>
>An idea from some folks at MIT apparently where a physical token
>consisting of a bunch of spheres embedded in epoxy is used as an
>access device by shining a laser through it.
>
>On the surface, this seems as silly as biometric authentication -- you
>can simply forge what the sensor is expecting even if you can't forge
>the token. Does anyone know any details about it?

This kind of thing has been done as "conformal coatings" in
nuke-tracking work.  Also diamond-tracking.  The idea is you
have a complex, optically-coupled-state (metal flakes or spheres
in clear paint/epoxy; crystal flaws) which you can read out but not duplicate.

This kind of 'unduplicable' conformal coating may appear on 
US-bound Canadian trucks, too.  Certify in the great white north,
spray, measure, drive, re-measure, pass, look ma, no long lines
at the border.








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