As a result of a mandate by the National Highway Traffic Safety Administration (NHTSA), beginning September 2007, all cars and trucks sold in the US must have a Tire Pressure Monitoring System (TPMS).

Here’s how it works: there’s a sensor, usually in the valve stem, that monitors information like pressure, temperature, and whether the tire is actually moving. That sensor – which has a unique ID – transmits to the car’s computer, much like your Bluetooth earpiece does to your cell phone. Since the transmitter has a unique ID, your car’s computer knows it’s only listening to its own tire sensors, and not the sensors on the car next to you. That information is broadcast as “clear text” – in other words, as something like ASCII (what’s ASCII? Hint: you’re looking at it). If you’ve figured out that the sensor is RFID and that both the data and your car’s identity get openly broadcast without any encryption, then you’ve figured out why I’m writing about it.

Continued