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Re: Digitally Signing Physical Objects
i wrote-
> >[Physical signature]
> > seems to have a tricky dependence on the tolerance. The forger can
> >get a valid plaintext and signed feature vector. So, if the tolerance
> >for error is too low, you get false positives, but if it's too high, a
> >forger could create something starting from the feature vector. An
> >interesting CAD/CAM problem.
Allen J. Baum replied-
> To keep black market forgery part off the market, a 30% tolerance is way
> more than enough. There should be no false negatives (making a real part
> look fake), but if 1/3 of the forgeries slip through (i.e. 2/3 don't), this
> has the affect of driving the forgery price up by a factor of 3,
> effectively pricing them out of the market.
I don't see how you factor out the variables of the resolution, what
physical property is scanned, etc. For some combinations, it would be easy
to forge 100% matches. For others, it would be hard to get a 30% match on
the original object... Maybe the whole scheme could be improved by a
trap-door function that has built-in error-tolerance. (By the way, if
anybody knows about fuzzy hash functions, please write me; I'm curious for
other reasons.)
> (Unless the real goods are overpriced a factor of 3...:-)
Isn't Great Art overpriced by thousands of times, in terms of reproduction
cost? Anyway, a 2/3 rejection rate would be tough.
-fnerd
quote me
- - - - - - - - - - - - - - -
We shall have to evolve
Problem solvers galore
As each problem they solve
Creates ten problems more. --Piet Hein
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