Modern automotive keys incorporate a tiny radio transmitter. The key sends a code to a receiver in your car, which unlocks the doors when it receives the correct code. The receiver (vehicle) and transmitter must be synchronised (with a key). If your key is faulty, it may not be able to deliver the signal to your car, leaving you locked out. A locksmith can program a replacement key for you. This is how auto key programming works.
Security is a top priority with today’s remote keyless entry technologies in cars. If people could easily unlock other people’s cars in a busy mall parking lot, it would be a serious problem.
Additionally, it would be best if you stopped anyone from “catching” the code that your transmitter emits due to the rise of radio scanners. Once they get your code, they could easily re-send it to gain entry to your car. This article discusses the working principle of modern car keys.
- The current 40-bit code is stored in a memory section on the controller chip of the transmitter. When you push a button on your key fob, the 40-bit code is delivered, along with a function code that tells the car what you want it to do (lock the doors, unlock the doors, open the trunk, etc.).
- The 40-bit code is also stored in memory space on the receiver’s controller chip. The receiver performs the requested function if the anticipated 40-bit code is received. Otherwise, it has no effect.
- Both the transmitter and the receiver employ the same pseudo-random number generator. The transmitter creates a new code each time a 40-bit code is delivered, using a pseudo-random number generator stored in memory. The receiver employs the same pseudo-random number generator to produce a new code each time it gets a legitimate one. As a result, the transmitter and receiver are in sync. If the recipient receives the anticipated code, the door will unlock. If you have a Honda, consider using only Honda replacement keys.
- If you accidentally push the transmitter button while you are a mile away from your vehicle, the transmitter and receiver get out of sync. The receiver resolves this problem by permitting any 256 permissible codes in the pseudo-random number sequence. If you (or your three-year-old child) “accidentally” pushed a button on the transmitter up to 256 times, the receiver would still take the message and perform the appropriate function. If you accidentally click the button 257 times, the receiver will entirely reject your transmitter. It will no longer work.
- Additionally, you can see that this form of rolling code transmitter does not support code capture. Older garage door transmitters used a DIP switch arrangement to send the same 8-bit code. The code may be easily taken and retransmitted to unlock the door by someone with a radio scanner. With a rolling code, recording the conversation serves no use. Re-transmitting the recorded code has no effect since it is impossible to predict which random number the transmitterand receiver will use as the next code. Since there are billions of options, it would take years to read through every code.
When considering buying a car, it is better to know how the car key works. It can help you be more cautious when parking your vehicle outside.