KEYLESS REPEATERS

Car Key Repeater: Understanding Relay Attack Devices & Security Risks

What Is a Car Key Repeater?

A car key repeater (also called a keyless repeater or relay attack device) is a radio frequency (RF) tool that intercepts, amplifies, and retransmits signals from wireless car key fobs. By extending the key's signal range, these devices can unlock and even start a vehicle remotely—even if the key is far away from the car.

How Does a Car Key Repeater Work?

1. Signal Interception – The repeater detects the low-power RF signal from a key fob (even through walls or pockets).
2. Signal Amplification – The device boosts the signal strength, allowing it to travel much farther.
3. Signal Relay – The amplified signal is transmitted to the car, tricking it into thinking the key is nearby.
4. Unauthorized Access – The vehicle unlocks and, in some cases, allows the engine to start without the real key present.

This method is known as a "relay attack" and is a major security concern for modern keyless entry vehicles.

Legitimate Uses of Car Key Repeaters

While often linked to theft, authorized professionals use these devices for:

1. Automotive Security Testing
✔ Manufacturers and security experts test keyless entry vulnerabilities to improve anti-theft systems.

2. RF Signal Range Analysis
✔ Engineers measure maximum key fob range to optimize vehicle security performance.

3. Locksmith & Security Training
✔ Professionals learn how relay attacks work to develop better protection methods.

4. Advanced Vehicle Diagnostics
✔ Developers use repeaters to simulate attacks and create more secure encryption (rolling codes, UWB, etc.).

Security Risks & How to Protect Your Car

How Thieves Use Key Repeaters
🔹 Two-Device Relay Attacks – One thief stands near the key (e.g., inside a home), while another near the car captures & relays the signal.
🔹 Quick Theft Method – Many modern cars can be stolen in under 30 seconds using this technique.

How to Prevent Relay Attacks
✅ Use a Faraday pouch (blocks key fob signals when not in use)
✅ Disable wireless key functions (if possible)
✅ Enable additional security (steering wheel locks, GPS trackers)
✅ Park in secure areas (garages, well-lit spots)

Legal Status of Car Key Repeaters

⚠ Warning:
- Unauthorized use of repeaters is illegal in most countries.
- Only licensed security researchers, locksmiths, and manufacturers can legally operate them.
- Possessing or using a repeater for vehicle theft can lead to criminal charges.

Conclusion

Car key repeaters pose a serious security risk but also help improve automotive protection when used legally. Vehicle owners should take precautions against relay attacks, while manufacturers continue developing more secure keyless entry systems.

🔒 Need a security upgrade? Consider Faraday bags, signal-blocking cases, or aftermarket immobilizers to protect your car from keyless theft.