unforgeable optical tokens?

[eli+ at zimbs4.srv.cs.cmu.edu]

I said:
>I can't dig up the memory, but I think I heard of a similar idea --
>random structure in transparent solid, difficult to copy -- used in
>some kind of tag or seal for nuclear security.  Can anyone remind me
>what this might have been?

Someone suggested in personal mail I look at the Slashdot discussion.
Thanks.  A couple of people there mention its use for tamper-evident
tags or seals or both (nobody seems too certain).  Google tells me the
DOD has entire conferences on seals, which I guess makes perfect
sense, and I imagine the details would be in there somewhere.

I looked at Ravikanth's dissertation, but it gave no direct reference
to this work.  It did reference "quantum subway tokens" and a recent
patent which used the random-solid idea; possibly the nuclear stuff
was assumed as prior work to those.  Putting this in the framework of
cryptography (as "physical one-way functions", etc.) seems to be one
of this thesis' contributions.

-- 
     Eli Brandt  |  eli+ at cs.cmu.edu  |  http://www.cs.cmu.edu/~eli/
    (finished Ph.D., woohoo; looking for good work in the Seattle area)

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