3 ms·
It must be possible to implement some kind of simple response time check. Given that the speed of light is ~1ns per foot then a total response time greater tha
by tomalpha 9y ago
It must be possible to implement some kind of simple response time check.
Given that the speed of light is ~1ns per foot then a total response time greater than (2d + p) where d = max distance in feet, and p = processing time within the keyfob in nanoseconds would provide a bound.
I suspect however that making the keyfob response time consistent might be the hardest part of the check, closely followed by an accurate timing facility within the car.
- maxerickson 9y agoYeah, the Wikipedia article talks about an implementation that has a processing time of 1 ns (which gives the distance within your foot). The questions are whether it is secure against the world or secure against just the implementers and how much it would cost.
- tjoff 9y agoAt the same time as being very low-power.