4 ms·

And the fix for this is for the keys to go to sleep when not being moved for x minutes. I can put my keys next to my car and walk away. After x minutes I cannot

And the fix for this is for the keys to go to sleep when not being moved for x minutes. I can put my keys next to my car and walk away. After x minutes I cannot open my car anymore unless I wiggle the keys. Example: https://www.youtube.com/watch?v=hRhYFXVo6To https://www.youtube.com/watch?v=hRhYFXVo6To

piffey 3y ago
Seems easy to defeat. I shake your car to make the alarm go off, hide, wait for you to pick up your keys to disable the alarm when you see no one there, use RF extender while your keys are active to unlock and steal the car.
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 ago
  the 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 ago
    You 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.
OtherShrezzing 3y ago
Even with that, this is a feature I'd be turning off. If your $75-125k car is vulnerable for 5 minutes per day at a predictable time and location, that's plenty of information for would be thieves. Keyless entry + keyless start means your vehicle could be gone before you've even got your shoes off after you get home.
kjs3 3y ago
There will be pushback because people leave their keys in the car. Hell, I probably know a dozen people who've told me "oh, I just leave the car keys in there". This is the kind of customer friction the car companies hate, so they likely won't do it, no matter if it's the 'right' answer.

piffey 3y ago

Seems easy to defeat. I shake your car to make the alarm go off, hide, wait for you to pick up your keys to disable the alarm when you see no one there, use RF extender while your keys are active to unlock and steal the car.

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 ago
the 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 ago
  You 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.

OtherShrezzing 3y ago

Even with that, this is a feature I'd be turning off. If your $75-125k car is vulnerable for 5 minutes per day at a predictable time and location, that's plenty of information for would be thieves. Keyless entry + keyless start means your vehicle could be gone before you've even got your shoes off after you get home.

kjs3 3y ago

There will be pushback because people leave their keys in the car. Hell, I probably know a dozen people who've told me "oh, I just leave the car keys in there". This is the kind of customer friction the car companies hate, so they likely won't do it, no matter if it's the 'right' answer.