What 'limits'? What 'acceptable range' are you talking about? I think they scan the surface doing pit depth / pit counts like an expensive cd reader. Within this presumption, you have to fingerprint either the whole document or a small square. It cannot be duplicated, it cannot be used to authenticate 'batches.' It could only be included in some piggyback data e.g. in the smartcard. Preferrably signed. With some glorious pki.
Keep trying, -Travis On Mar 19, 2010 7:20 PM, "mrx" <[email protected]> wrote: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 [email protected] wrote: > On Fri, 19 Mar 2010 20:51:40 -0000, mrx said: >> Consider a production line for printing anything ... If deviations in the manufacturing process were consistently between known limits, it still serves as a control. A hacker may learn those limits but then the problem of recreating an equal manufacturing process still remains. Obviously if the deviation in each sample is such that the known level of consistency is so wide that the process is easily replicated then the tech is useless as an indicator of integrity. > A bigger concern is whether normal wear and tear will invalidate the > measurements - some spots ... Yes I would agree, but for tokens of limited lifetime perhaps there is still potential. Concert tickets, travel tickets etc. Besides one could always force renewal of the token once it's valid lifetime has expired. I still think there may be a potential security benefit here. mrx - -- Mankind's systems are white sticks tapping walls. Thanks Roy http://www.propergander.org.uk --... iQEVAwUBS6QExrIvn8UFHWSmAQJnygf/dUiVo37byk9WFfk1PTigC/ZJNYxr7iuB JZ9Pv/H2d0YI8M/ru54B5Q6rO7RFqDDRJhlgAjLLOY6R1p2D9ai6NvM+yJWfI5eb gtqOLaV6s4KSY2pl40CYXm26cVOmascglyFOdwSdH76Lu8EERqI7woKra6PNBXv2 1olRAcNr8qmYY6DxBDJPZ1Q3J6/FtGIkMHjh1eg3ysoGtgfPk3TQnusgjqgY5Omp 6MG1Q4wPosVCRAH3igvkR8zRLFpkCgBlHsoV/qvK+poPf4o2h5UNqXIK7jVLrz70 RQmZIH+GrWlXjSS1VLYYf+OHe1W0gRirruS2otj14WqfLvyLrKl3iQ== =TlBw -----END PGP SIGNATURE----- _______________________________________________ Full-Disclosure - We be...
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