unforgeable optical tokens?

[David Wagner]

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.

Yeah.  I think it's neat!

This is not a replacement for cryptography.  It's not biometric
authentication.  It's no good for challenge-response authentication
across a network.  It's not a secure credit card.

What is it, then?  It's a physical object that's hard to duplicate.
I'd describe their work by analogy to marbles.  Marbles are more-or-less
unique.  When I first meet you, I could give you a marble, and if I
see you again a little bit later, I can know it's you again by the fact
that it's the same marble, just by looking at your marble.  Also, their
"marble" has the property that someone else who peeks at your marble
won't be able to easily duplicate your marble.  Their "marble" requires
a special reader to scan the token, though.

What are the applications?  Well, you can imagine this might be useful
to stop counterfeiting, for instance.  Maybe our future dollar bills
could include such a strip, and cheap readers could be used to validate
the authenticity of a bill.

I think it will take some time to validate how secure their proposal
is, but it is an intriguing new idea that might just work.  Also, it
remains to be seen whether their technique will be cheap enough to be
cost-effective; still, I'm intrigued.

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