Car Remote Key Fob Security

Car Security System: Security has come a long way using high technology and miniaturization in circuits. The key fob you have in your hand is really a sophisticated piece of technology that offers 40 bit code ( or more)with one trillion (1 followed by 12 zeros) possible combination codes. The chances of others opening your car through other remotes are remote. The remote key fob security uses a technique called as Hopping Code. This technique doesn't use the same code every time. If it used the same code, car thieves can use a Radio Scanner in what is called as Code Grabbing to record the transmission between the car remote key and the car receiver to fool the car into thinking that the authentic owner has issued the command.

In this Hopping code technique they use a rolling code - a code that keeps changing every time. This method of security using NLFSR (Non linear feedback Shift Register) is hard to beat at the present stage. You might wonder how the transmitter and the receiver manage to keep synchronized. They do that using a pseudo random number which they agree upon. So every time you press the key, the transmitter sends a new code to the receiver. The receiver accepts the code if it is one of the possible 256 pre-arranged codes. The 256 extra options are given because if you press the key away from the normal receiving area of the car, the transmitter steps out of synchronization otherwise. Thus you are given 255 chances of staying within sync with the receiver in the car. The decoder in the receiver activates only when the next expected code in the hopping code sequence is received - any interception and subsequent retransmission of the same code released previously will not activate the decoder function.

If for some reason the transmitter and the receiver steps out of synchronization - possibly because the encoder in the transmitter was not near the receiver for more than 256 times, then manual re synchronization may need to be done. Check your car manual for the exact sequence.

We find from the technical manual of this chip (Multi Channel Advanced Remote Control Serial Transmitter and receiver family) manufacturer (Texas instruments) representative of such technology that on average the chip stores the contents for up to 10 years. It can operate between -40 degree C and 85 degree C - a typical scenario unlikely to be exceeded in a car.

Safeguard your car Security

The remote key fob uses many types of batteries for their functioning. Mostly they may use a 3 V Li-Ion button type cells or a slender 12 V type depending on the manufacturer. Most remote batteries last for about 2 years. But don't go by the time scale alone. If the battery is weak, there will be some tell-tale signs you need to watch out for. The range will come down. The red LED which lights up to indicate that you are pressing a key will 'look' weak. Change the battery at the first sign. The slender tubular battery also tends to leak corroding the printed circuit board. So if you have this type in your keys - change them every alternate year.

Modern Car Remote Keys are generally tolerant of normal day-to-day abuse and occasional drop on a hard floor. But don't expect them to survive a drop from the 1st floor. The chips and the few passive components your car remote key has may survive the fall as they are surface mounted devices but the power transistor or the chip transmitter may not be that lucky. They don't take kindly to immersion in water either.

In many modern cars, merely the presence of the remote key fob in you can trigger the receiver to open the car doors. This system operates by detecting a low power Radio frequency signal constantly emitted by the car and the remote car key fob sends the suitable code sequence without requiring any key to be manually pressed. This sort of communication requires that you have the key on you and you need to be less than 8 meters from the car to work reliably. But this can be a security issue if someone can mimic the car signal near you and activate your transmitter to send the activation code which can be captured and sent to the car. This necessitates at least 2 perpetrators - one near you and another near the car. The technology is available to conduct such 'hacking'. If your car key has the option to disable 'automatic' or 'Hands free' opening of the door, use that in a crowded parking area. It your remote key doesn't have the option of disabling that, find an aluminium wallet or an all metal wallet and keep the key inside. Just make sure when your key is inside the wallet, the car doesn't open the door even when you are near the car.

In addition to the security outlined above, there is another car security technique to protect any one from starting your car which uses RFID (Radio Frequency Identification Device) technology. Your car key's plastic top cover may contain a tiny RFID chip which when queried by the car ( the receiver lives close to the ignition key socket) sends out an unique digital code. If the code matches the one stored in the car, the immobilizer deactivates and allows the car engine to be started. If the RFID code doesn't match the car, the immobilizer will not allow the car to start.