Leaving your car keys in the microwave is a method some people use to protect their keyless entry fob from being hacked or stolen via a method known as a “relay attack.” The reasoning behind this practice is similar to placing your keys in the refrigerator, as both appliances can block the signal emitted by the key fob. Here’s why this technique might be used:
1. Signal Blocking
- Keyless Entry Systems: Many modern vehicles are equipped with keyless entry systems that allow you to unlock and start your car without physically inserting a key. The key fob emits a signal that your car recognizes when you are nearby.
- Relay Attacks: Thieves can use devices to intercept and amplify the signal from your key fob, even if it is inside your home. By capturing and relaying this signal, they can trick your car into thinking the key fob is in close proximity, allowing them to unlock and steal your vehicle.
2. Microwave as a Faraday Cage
- Electromagnetic Shielding: A microwave oven is designed to contain electromagnetic waves and prevent them from escaping, which is why it can be used as a makeshift Faraday cage. When you place your key fob inside the microwave (without turning it on), the metal shielding of the microwave can block the signals that the key fob emits, making it difficult for thieves to intercept them.
- Signal Interference: By putting your keys in the microwave, you can prevent the signal from your key fob from being broadcasted beyond the walls of the microwave, reducing the risk of relay attacks.
3. Practicality and Caution
- Convenience: For people who don’t have a Faraday pouch or other signal-blocking device, using a microwave that’s already in the home can be a quick and effective solution.
- Safety Warning: It is crucial never to turn on the microwave while your keys are inside. The microwave is not designed to heat metal objects, and doing so can cause damage to the microwave and potentially start a fire. Always ensure the microwave is off and unplugged when using it for this purpose.
4. Temporary Solution
- Short-Term Protection: While this method can be effective in the short term, it’s not necessarily a practical long-term solution. A Faraday pouch or a signal-blocking box, specifically designed to block key fob signals, is more convenient and safer for regular use.
