unforgeable optical tokens?

[Trei, Peter]

> Hadmut Danisch[SMTP:hadmut at danisch.de]
> 
> On Fri, Sep 20, 2002 at 12:07:38PM -0400, Perry E. Metzger wrote:
> > 
> > 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.
> 
> 
> Mmmh, assuming that this is really difficult to forge, it's not
> silly and doesn't compare to biometric authentication. 
> 
	[...]

> Hadmut
> 
It appears to have replay resistance *between* readers - ie, the data
from reader A would be useless to spoof reader B, since the two readers
will illuminate the device at different locations and angles. 

I would worry about durability - they mention that a 0.5 mm hole can 
destroy the token. It would appear that dust, scratches, etc could
also invalidate it. Sure, it can be encased, coated, etc, but that all
raises the cost.

Peter


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