3 ms·
Fortunately, this problem has an easy solution. IEEE 802.15.4 UWB (Ultra-Wideband) radios with timestamping functionality allow measuring the time of flight (w
by jwr 9y ago
Fortunately, this problem has an easy solution.
IEEE 802.15.4 UWB (Ultra-Wideband) radios with timestamping functionality allow measuring the time of flight (well, not directly, but it can be inferred from an exchange of messages) of your signal. With some added crypto, it isn't difficult to build a solution which is limited to a specified distance. You can get as precise as ±20cm.
This means that you can build a system which will not work beyond a certain distance, because signals will take too long to travel.
I'm surprised this hasn't been picked up by car manufacturers yet. Perhaps there is too little market pressure.
- londons_explore 9y agoThe time of flight is not cryptographically secure. Ie. an attacker can trick it. There are protocols which are though: https://en.wikipedia.org/wiki/Distance-bounding_protocol https://en.wikipedia.org/wiki/Distance-bounding_protocol
- xr4ti 9y agoSure. However, I think the objective would to increase difficultly and the level sophistication required for exploitation rather than compete security. For instance, a physical lock on your front door can easily be defeated by someone with the requisite tools and expertise, but that doesn't make them useless as a security measure.
- jwr 9y agoBy itself it isn't, but use the timestamps as part of an authenticated exchange, and you're fine.