Keyless entry for cars is incredibly convenient, but it also introduces a potential security risk. With the rise of relay attacks, thieves can exploit the signals from your key fob to gain access to your vehicle and even drive away with it. One proposed solution to this problem is the Faraday box, or Faraday pouch – a container designed to block electromagnetic fields and prevent these signals from being intercepted. But do these protectors really work, or are they just another gimmick? To find out, we decided to conduct our own DIY test using materials you might already have at home.
We’d read about different approaches to creating a Faraday box, ranging from specialized RFID-blocking fabrics to simple household items. Among these, lining a box with tin foil seemed like the most accessible DIY method. Skeptical but curious, we decided to put the tin foil Faraday box to the test. Could a simple cardboard box lined with tin foil actually block the signal from a key fob? To find out, we grabbed some cardboard, tin foil, and a key fob, and set up a simple experiment.
Our initial attempt involved constructing a small cardboard box and lining it with two layers of standard kitchen tin foil, carefully sealing all the seams. To test its effectiveness, we placed a smartphone inside the makeshift Faraday box and attempted to call it from another phone. The idea was straightforward: if the box effectively blocked electromagnetic signals, the phone inside should not receive the call. If it rang, it would indicate a failure in the shielding. Much to our initial dismay, the phone rang. It seemed our DIY Faraday box was a bust.
However, upon closer inspection, we noticed a tiny gap in the tin foil seam, barely two centimeters long and less than a millimeter wide. Could this small imperfection be enough to compromise the entire Faraday cage? We carefully sealed the gap and repeated the test. This time, the phone remained silent. No ringing. The call did not go through.
To our surprise, the humble tin foil Faraday box actually worked! By ensuring complete coverage and eliminating even small gaps, we were able to effectively block the phone signal. This simple experiment demonstrated the principle behind Faraday boxes and their potential to block key fob signals. While our DIY box was a success in this test, for everyday use and guaranteed protection, commercially available Faraday pouches or boxes are likely a more practical and reliable solution. These are often constructed with multiple layers of specialized RFID-blocking materials and are designed for the specific purpose of key fob protection, offering a more convenient and durable way to safeguard your vehicle from relay attacks.
