4 ms·

So, the attack starts out with the car stopped, and some sort of equipment to amplify the keyless entry signals to the car and vice versa, so the car thinks the

So, the attack starts out with the car stopped, and some sort of equipment to amplify the keyless entry signals to the car and vice versa, so the car thinks the key is within range. The car starts, and they drive away from the amplification system. What happens when the car drives out of range of the key while it is running? Does the engine just turn off, or does it keep going until you press the engine off button? I wish I had a car to experiment with... but on the other hand I'll stick with the old fashioned keys, even if those are rather easy to get past too.

Deestan 16y ago
> What happens when the car drives out of range of the key while it is running? Does the engine just turn off[...]? Would be nasty. Imagine the car key running out of battery on the motorway.
- kreneskyp 16y ago
  The key doesn't have a battery. It's usually RFID.
  - count 16y ago
    On my Lexus it's both active and passive RFID. If you start the car and the key is 'active', you have to keep it in the cabin, or the car starts complaining (I've not been brave enough to drive with it not in there...). If you start the car with the key as passive (ie: dead battery - you have to hold it on the ignition button to be detected), it recognizes the difference and doesn't complain.
    - kreneskyp 16y ago
      Just because it's "active" doesn't mean the FOB needs a battery for the RFID to work. The car could periodically check for the key. If your RFID required a battery, and required that it constantly be on, then the battery would need to be replaced often. Couple this with your car potentially shutting off in the middle of the highway and you've got a very unsafe car. I know for certain that VW keys do not need the battery for the RFID to work. The battery is only used for remote lock/unlock. Perhaps other cars are different, but I'd consider that a design flaw. edit: forgot to mention that my VW does not even have physical locks except for the glovebox. A dead rfid battery, if it had one, would mean i was stranded. I'm actually not sure what happens if my car battery dies while the car is locked.
      - count 16y ago
        The fob battery does die fairly often (replace it once/twice a year?). My car has no visible physical locks - there's a small notch under the drivers door handle you can pop off a piece of the handle using the fob, and then there is a physical lock you can get into the car with (no way to open the trunk until you turn the car on). I've had to do this a few times :) Like I said, you can still use the key to start the car, but if the battery is dead, you have to hold it up to the start button.
  - kgermino 16y ago
    Are you sure, It seems like RFID without batteries would run into range problems. I know mine has a battery.
    - kreneskyp 16y ago
      RFID range is between 3-20 feet. Average human arm length is less than 3 feet. The limiting factor here is not RFID range.
stonemetal 16y ago
The car keeps running, or at least the Prius does.

Deestan 16y ago

> What happens when the car drives out of range of the key while it is running? Does the engine just turn off[...]? Would be nasty. Imagine the car key running out of battery on the motorway.

kreneskyp 16y ago
The key doesn't have a battery. It's usually RFID.
- count 16y ago
  On my Lexus it's both active and passive RFID. If you start the car and the key is 'active', you have to keep it in the cabin, or the car starts complaining (I've not been brave enough to drive with it not in there...). If you start the car with the key as passive (ie: dead battery - you have to hold it on the ignition button to be detected), it recognizes the difference and doesn't complain.
  - kreneskyp 16y ago
    Just because it's "active" doesn't mean the FOB needs a battery for the RFID to work. The car could periodically check for the key. If your RFID required a battery, and required that it constantly be on, then the battery would need to be replaced often. Couple this with your car potentially shutting off in the middle of the highway and you've got a very unsafe car. I know for certain that VW keys do not need the battery for the RFID to work. The battery is only used for remote lock/unlock. Perhaps other cars are different, but I'd consider that a design flaw. edit: forgot to mention that my VW does not even have physical locks except for the glovebox. A dead rfid battery, if it had one, would mean i was stranded. I'm actually not sure what happens if my car battery dies while the car is locked.
    - count 16y ago
      The fob battery does die fairly often (replace it once/twice a year?). My car has no visible physical locks - there's a small notch under the drivers door handle you can pop off a piece of the handle using the fob, and then there is a physical lock you can get into the car with (no way to open the trunk until you turn the car on). I've had to do this a few times :) Like I said, you can still use the key to start the car, but if the battery is dead, you have to hold it up to the start button.
- kgermino 16y ago
  Are you sure, It seems like RFID without batteries would run into range problems. I know mine has a battery.
  - kreneskyp 16y ago
    RFID range is between 3-20 feet. Average human arm length is less than 3 feet. The limiting factor here is not RFID range.

stonemetal 16y ago

The car keeps running, or at least the Prius does.