3 ms·
No, the fix for an attack that extends the readable distance via a relay is to use timing information in the authentication process between the key and the car.
by Borealid 3y ago
No, the fix for an attack that extends the readable distance via a relay is to use timing information in the authentication process between the key and the car.
Car: "please respond to challenge blah"
Key: ENC(car-public-key, SIGN(blah))
Car: "too slow"
Physics itself limits how quickly you can do a round-trip to a device that's a certain distance away. If the timeout for the operation is set near enough to those physical limits, a relay attack won't work.
- nullc 3y agothe latency auth trick requires very fast timings, to distinguish between 5 ft and 25 ft... 20 feet difference is like 20 ns. (the attacker's parts don't need to be high delay themselves, could be a pair of gain antennas and amplifiers.)
- contravariant 3y agoYou could of course use a phase difference instead of trying to measure sub nanosecond timings, but honestly it sounds like a nightmare to get right. Distance travelled by light will probably turn out to have very little in common with how we think it ought to work.