4 ms·

Doesn't the system already check the latency from key fob to car antenna? Better yet, you could use two antennas in the car, and triangulate the key fob.

• rocqua 3y ago
  The latency check is usually not sensitive enough to prevent a car being stolen from the drive-way from a relayed key that lies near the front door. For reference 20 meters is about 66 nano-seconds.
  • gruez 3y ago
    Why not? A 2GHz is very attainable in modern CPUs and translates to 0.0005ns per cycle. This isn't theoretical either. 802.11mc[1] is a real standard and is accurate to 1-2m. [1] https://en.wikipedia.org/wiki/IEEE_802.11mc https://en.wikipedia.org/wiki/IEEE_802.11mc
    • hanche 3y ago
      Aren’t you off by three orders of magnitude? 2GHz translates to 0.5ns per cycle. Or perhaps you meant to write ms.
      • gruez 3y ago
        Whoops, you're right!
  • gsich 3y ago
    So, solvable?
  • sebk 3y ago
    UWB is augmenting Bluetooth for car keys solving this exact issue; The Car Connectivity Consortium came up with the Digital Key 3.0 standard that's available today, as implemented by some makes like BMW and the Hyundai/Kia group and Apple, and resists relay and replay attacks through precise ranging.