-----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 that is used for access >> control. Now providing there is absolutea consistency across every sample of >> the >> material printed/magnetised or otherwise marked during a production run, then >> only one token need be scanned by laser. > > I thought the point was that there *wasn't* absolute consistency, and what > was being measured was the deviations in each sample.
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 will be rubbed smoother by friction, others > will be roughed up. Yes, the fine article says this: > > "This continued even after they were subjected to rough handling, including > submersion in water, scorching, scrubbing with an abrasive cleaning pad and > being scribbled on with thick black marker." > > But I wonder what several years of wear will do. 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 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEVAwUBS6QExrIvn8UFHWSmAQJnygf/dUiVo37byk9WFfk1PTigC/ZJNYxr7iuB JZ9Pv/H2d0YI8M/ru54B5Q6rO7RFqDDRJhlgAjLLOY6R1p2D9ai6NvM+yJWfI5eb gtqOLaV6s4KSY2pl40CYXm26cVOmascglyFOdwSdH76Lu8EERqI7woKra6PNBXv2 1olRAcNr8qmYY6DxBDJPZ1Q3J6/FtGIkMHjh1eg3ysoGtgfPk3TQnusgjqgY5Omp 6MG1Q4wPosVCRAH3igvkR8zRLFpkCgBlHsoV/qvK+poPf4o2h5UNqXIK7jVLrz70 RQmZIH+GrWlXjSS1VLYYf+OHe1W0gRirruS2otj14WqfLvyLrKl3iQ== =TlBw -----END PGP SIGNATURE----- _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
