I hope most of the key less entry cars are using rolling codes in order to improve the security between the key fob and the car. Is it possible to intercept this communication using a device such as HackRF?

Can we jam the signal from the key fob to the car and replay it later to crack the rolling code sequence? If so, how can we secure this?

2 Answers 2


If I'm not mistaken, there's a pretty decent security hole with car keys. If a car-key transmits one of it's rolling codes and the car does not received it. That code is still valid until the car receives a new code from the key. In the meantime, a listener could have picked up the code and be able to use it.

The attack vector is something like: While away from your car someone gets a hold of your keys briefly and presses the unlock button, they snoop the code and then go off and unlock your car without you knowing.


Yes, it is, using either the HackRF or other SDR devices capable of replaying the signal. You can jam the key fob by simply listening to the signals, the frequency on which the key fob operates gets interferred, then you are free to use the first code you got and store the later one to open the car in another moment. To secure against this hashing the button should do it, or using time-based algorithms

Source: https://www.youtube.com/watch?v=1RipwqJG50c

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