Marcus J Ranum wrote :
> Robertson, Paul writes:
> > Also, does anyone have any info on what algorithm they use?
> Their clock-sync algorithm is patented, but should be intuitively
> obvious. Looks like they just DES encrypt the clock modulo some granularity
> with a secret key that is stored on the card. The server performs the same
> encryption using its clock, then applies a skew based on the last time the
> card successfully authenticated, with a sliding window to allow for greater
> drift latitude over time. Just a guess, though.
I don't think it's DES, since they can (and do) export it, but from what they
told me, you guessed right about the rest.
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