That's basically what it is doing now... except that the message from the car is relayed over another radio to a radio the attacker is carrying near the victim. The victim's key thinks it is near the car, and signs the message which then is sent back over radio to the car.
This isn't about better cryptography. This is about how can the car know that the key is in close proximity to it? We can transmit data long distances.
Timing is going to be the key, how much time is allowed to be passed between sending a challenge and getting a response? Right now there is a lot of "slop" to allow the owner with the key to be turned away from the vehicle and things to still work, or have it in your left pocket versus your right when seated in the car.
My Subaru WRX requires the key to be right next to the middle console, so I can only keep my key in my right pocket. If I have it in my left pocket I can't start my car.
I don't know how much "timing" slop there is though. Could someone relay my keys transmission with a short delay?
This isn't about better cryptography. This is about how can the car know that the key is in close proximity to it? We can transmit data long distances.
Timing is going to be the key, how much time is allowed to be passed between sending a challenge and getting a response? Right now there is a lot of "slop" to allow the owner with the key to be turned away from the vehicle and things to still work, or have it in your left pocket versus your right when seated in the car.
My Subaru WRX requires the key to be right next to the middle console, so I can only keep my key in my right pocket. If I have it in my left pocket I can't start my car.
I don't know how much "timing" slop there is though. Could someone relay my keys transmission with a short delay?