In early August 2022, an ad on Yahoo.com claimed, “Wrap Your Car Keys in Foil at Night When Alone.” The wording appeared to hint at a critical security reason such as keeping your car’s electronic key fob signal safe from criminals. The ad led to a 64-page slideshow article. None of the pages mentioned anything about wrapping car keys in tinfoil, because it was clickbait.
We hope we saved readers from making all of the “next page” clicks in the slideshow article. However, we didn’t want to stop there. After doing some digging, we noticed that the idea of wrapping car keys in foil had appeared in the news before. This led us to wonder what this was all about.
We’ll tell you right off the top that, yes, wrapping your car’s key fob in foil or placing it in a metal container or special pouch might keep its signal — whether the always-on low frequency or the button-pressed higher frequency — secure from criminals. However, these methods would likely not be foolproof, as the fob likely has to be removed from its protective covering to start and drive the car. Also, while recorded incidents of this kind of crime are on the rise, don’t lose sight of the fact that, like many crimes, the likelihood of someone being targeted by criminals via their keyless entry technology are relatively low.
In this story, we’ll explain how key fobs work, perform some basic tests, and go in-depth into how criminals have been trying to exploit the technology.
How Electronic Key Fobs Work
Central to this subject are car key fobs, the electronic devices attached to key rings that contain buttons to lock and unlock your vehicle. They also often have a red button to sound your horn or alarm, referred to sometimes as a “panic” button. Some more modern fobs can even start your car’s ignition from afar.
According to tctechsystems.com, “key fobs use radio waves to communicate with a reader in the door latch that they are programmed to open” on “a system known as radio frequency identification (RFID), which operates like an electronic barcode for identification purposes.”
The idea of wrapping your fob in foil might sound a bit odd and lead to thoughts about tinfoil hats, as if it’s something only a paranoid person would do. So what are the facts about car key fobs and foil? We did some digging and decided to print our findings on a single page (as opposed to, let’s say, a 64-page slideshow article).
Testing Car Keys with Foil
We performed a simple test with three vehicles. The results from this small test showed that it appeared to sometimes be true that wrapping a key fob in aluminum foil could keep your car’s special signal (code) contained.
For example, we found that a Toyota key fob wrapped in foil was not able to send a signal to the car, even when positioned inches away from the vehicle. A test of a Mazda key fob wrapped in foil showed that it wouldn’t function from just a few feet away. A third test with a key fob for a Subaru showed that the device couldn’t reach the vehicle from 20 feet away, but could successfully perform functions from just ten feet away.
In other words, the results were a mixed bag and perhaps depended on the make or year of the car, or both. The results may also have been impacted by the different thicknesses of foil used.
Criminals Targeting Car Key Fobs
Why would someone want to contain their key fob’s signal within a tiny space, surrounded by foil? According to a 2019 press release from the American Automobile Association (AAA), some car thieves have been known to take advantage of exploits in keyless entry technology. Keyless ignition technology may also be more vulnerable, and refers to car key fobs that can start the vehicle with the press of a button. Criminals can even potentially access the signal sent by a key fob that’s inside the car owners’ home:
More than half of the cars sold in the United States in 2018 came equipped with a keyless ignition system. Once only available on luxury vehicles back in the early 2000s, keyless ignition systems are popular accessories on all makes and models. They are popular with car thieves. Never underestimate their ingenuity. “Another way that criminals exploit the key fob is during the process of locking the vehicle,” warns Interpol. “As you lock your car, criminals can intercept and block the ‘lock signal’ sent by the key fob to the vehicle, leaving it unlocked. The criminal can then easily steal the contents inside the vehicle, or the vehicle itself.”
“Many of today’s cars use keyless entry/ignition ‘smart fobs’ that allow the car to be unlocked and started without removing the fob from one’s pocket or purse,” said John B. Townsend II, AAA Mid-Atlantic’s Manager of Public and Government Affairs. “The vehicle and fob communicate using low-power radio signals that are only effective when the fob is within approximately 36 inches of the car door or ignition start/stop button. Thieves can amplify the signal sent by your key fob to unlock [the] door and break-in your car and rife through your vehicle and steal it too. It is spawning a wave of keyless car thefts known as ‘relay attacks.’”
AAA defined “relay hacks” executed by criminals as a way of amplifying the communication signals between vehicles and fobs, “‘tricking’ the car into thinking the fob is next to the car door or trunk when it is somewhere else.” This apparently mostly involves the theft of personal property inside the vehicle and not so much the stealing of the car itself, as “once the car has been driven out of range of the smart fob and shut off, it cannot be restarted.”
Guidance on Protecting Fobs
In 2019, the National Insurance Crime Bureau (NICB) recommended four security steps to ensure you keep your vehicle and the belongings inside your car safe:
1. Lock the vehicle, set the alarm, and take all keys or FOBS.
2. Do not leave the garage door opener in the vehicle.
3. Take a picture of your registration on your cell phone and do not leave the registration or other papers with personal information in the vehicle.
4. Never leave a car unlocked and running to warm it up or while stopping for a quick cup of coffee. It only takes a moment for the opportunistic thief to jump inside and drive off.
By email, AAA did not specifically provide to us guidance about foil but did mention metal containers:
1. Don’t leave valuable items (purses, GPS units, shopping bags or electronics) in your car. If you must do so, make sure they are out of sight in a locked glove box or trunk.
2. Park your car in a closed garage; this makes it a far less inviting target.
3. Store your key fobs (all of them) in a metal container when not in use. The metal provides a barrier that interrupts radio signals to/from the smart fob.
4. Alternatively, inexpensive “RFID sleeves” and “Faraday bags” are available that have metal mesh linings that will shield a key fob from sending or receiving radio signals.
5. Do not place key fobs in a freezer or microwave oven, as these methods may damage the fobs, which can cost hundreds of dollars to replace and program.
We reached out to NICB with a few questions similar to what we asked AAA about and will update this story if we receive a response.
Note: Have you been targeted by criminals who were seeking your key fob radio frequency data? Do you want to share your story with our readers? If so, contact us. Please include evidence such as a police report or other official documentation, so that we can verify the details.
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Agatie, Cristian. “Ford Patents Key Fob Relay Attack Prevention System, Will Make Stealing Cars a Lot Harder.” Autoevolution, 13 May 2022, https://www.autoevolution.com/news/ford-patents-key-fob-relay-attack-prevention-system-will-make-stealing-cars-a-lot-harder-188742.html.
Bond, Casey. “Does Wrapping Your Car Key In Tin Foil Really Prevent Theft?” HuffPost, 21 Nov. 2019, https://www.huffpost.com/entry/car-key-in-tin-foil-fob-relay-attack_l_5db8d269e4b00d83f71ef35a.
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“How Do Key Fobs Work? – How to Program a Key Fob.” TC Tech Systems, 22 July 2019, https://www.tctechsystems.com/how-key-fobs-work/.
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Townsend, John, and Ragina C. Ali. “Car Thieves Are Targeting Keyless Fobs To Snatch Your Car; Auto Thefts Are On The Rise As Drivers Leave Fobs In Their Cars.” AAA News & Press Releases, 19 Dec. 2019, https://cluballiance.aaa.com/public-affairs/press-release/?rdl=midatlantic.aaa.com&Id=f0e8cf35-3b05-4638-950b-00233a48cc10.
Tsukayama, Hayley. “Should Your Car Keys Be Wearing a Tinfoil Hat?” Washington Post, 12 July 2028, https://www.washingtonpost.com/technology/2018/07/12/should-your-car-keys-be-wearing-tinfoil-hat/.