Let's say you just bought a Mercedes S550--a state-of-the-art, high-tech vehicle with an antitheft keyless ignition system.

After you pull into a Starbucks to celebrate with a grande latte and a scone, a man in a T-shirt and jeans with a laptop sits next to you and starts up a friendly conversation: "Is that the S550? How do you like it so far?" Eager to share, you converse for a few minutes, then the man thanks you and is gone. A moment later, you look up to discover your new Mercedes is gone as well.

Now, decrypting one 40-bit code sequence can not only disengage the security system and unlock the doors, it can also start the car--making the hack tempting for thieves. The owner of the code is now the true owner of the car. And while high-end, high-tech auto thefts like this are more common in Europe today, they will soon start happening in America. The sad thing is that manufacturers of keyless devices don't seem to care.

Wireless or contactless devices in cars are not new. Remote keyless entry systems--those black fobs we all have dangling next to our car keys--have been around for years. While the owner is still a few feet away from a car, the fobs can disengage the auto alarm and unlock the doors; they can even activate the car's panic alarm in an emergency.

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