Cryptography researchers from Johns Hopkins University have cracked the popular "immobilizer" security system used in "more than 150 million Ford, Toyota, and Nissans." The security system from Texas Instruments uses an RFID transponder built into the car key. The car looks for a signal from the key when you try to start it. If it does not get the proper code response from the key, the car doesn't start.

The researchers said that it would be possible to extract the built-in code from a person's key by standing next to them then, after some computing time, turn around and "feed the code to the car and hot-wire it." The technique could also apply to those keychain wands used to purchase gas by waving it past a reader on the gas pump.

This case brings into focus not just the possibility of college students stealing cars and gas, but the insecurity of transmitting important information over radio waves. As industry begins to rely on the promise of RFID, it must also address real security issues as they arise.