Electronic Key Fobs

I’ve never been that thrilled with them. The one on our BMW has a failed lock button, and it’s over $200 to replace. But here’s another problem:

The teenagers, he said, likely got into the car using a relatively simple and inexpensive device called a “power amplifier.”

He explained it like this: In a normal scenario, when you walk up to a car with a keyless entry and try the door handle, the car wirelessly calls out for your key so you don’t have to press any buttons to get inside. If the key calls back, the door unlocks. But the keyless system is capable of searching for a key only within a couple of feet.

Mr. Danev said that when the teenage girl turned on her device, it amplified the distance that the car can search, which then allowed my car to talk to my key, which happened to be sitting about 50 feet away, on the kitchen counter. And just like that, open sesame.

“It’s a bit like a loudspeaker, so when you say hello over it, people who are 100 meters away can hear the word, ‘hello,’ ” Mr. Danev said. “You can buy these devices anywhere for under $100.” He said some of the lower-range devices cost as little as $17 and can be bought online on sites like eBay, Amazon and Craigslist.

Mr. Danev said his company was in talks with several car manufacturers to install a chip that can tell how far the key is from the car, thereby defeating the power-amplifier trick.

I’d think that putting the key in the microwave would work as well as the freezer, except you risk accidentally cooking it. That wouldn’t be a problem with our new unit, though — it won’t let you start it without opening and reclosing the door.

6 thoughts on “Electronic Key Fobs”

  1. A related issue; any kind of remote control, such as a keyfob that opens doors at the push of a button, or a garage door opener, is vulnerable to a signal grabber (unless it uses rolling-code). Simply record a use, then play it back later. Many garage doors openers have rolling code these days, but if it also has the ability to program an older remote into it, this bypasses the rolling code protection without, at least in some cases, mentioning this risk in the instructions.

    And, regarding the RFID chips in the article, a further reason I don’t like them; some unlock ALL the doors when you approach your car. This is very handy for a robber-carjacker hiding on the far side.I prefer that my vehicle stays locked until I unlock it. I’ll stick to a rolling code button activated entry that unlocks the driver door only unless you press it twice.

    I also hate RFID chip based credit cards for the same reason; way too easy to remotely grab the code.

  2. I can’t think of an inexpensive way to “tell how far the key is from the car.” Obviously, you can’t deduce it from the power. You’d have to have some kind of two way ranging. There are other options, but many $$$ and probably a very bulky key.

  3. Regarding the prevention of this particular method of theft by surrounding it with conductive material: The thickness of the conductive material is immaterial. Which means that lining your pocket with the sort of stuff emergency blankets are made of might well work. Or your handbag, if that’s where you keep your key.

    I’m told that this is a tactic fairly commonly used by shoplifters, incidentally.

  4. I thought about this some more. Isn’t the authentication a query-and-response? Just because the car can scream out to 100 meters doesn’t mean that the key can scream back as loudly.

    Just because the cattlemen can hear the bell/triangle for dinner doesn’t mean they can tell you how many potatoes they want on their plate.

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