The recent trend of thieves replicating your key fob signals to steal your car has got me worried. I want to use a box to store my keys at home and to block them from access while I am asleep.

I want to use a cigar box for decorative purposes. What can I use as a "liner" in the box to block my car fob signal? Layers of aluminum? Lead? Where would I get that much lead??? I can buy something off Amazon but it doesn't match my decor and it's expensive.

Lining the inside of a cigar box with aluminum foil should be sufficient. With some tape or contact paper the inside should be durable, basically a small faraday cage.

I found out how spectacularly easy it was to copy/clone these fobs.

While making a few upgrades, I deactivated the receiver and removed it from the vehicle control module.

I have to use the key for the door now, which I don't mind. Changed the code for the transponder as well.

Is that necessary?

I know the signals can be intercepted if a receiver is near you when you push the Fob unlock button, but I've never heard of something that can scan an idle fob.
Or am I just unaware of a new development?

quote:

Originally posted by WaterburyBob:
I've never heard of something that can scan an idle fob.
Or am I just unaware of a new development?

That was my immediate question as well.

Shortly before I moved out of NH my Audi and about a dozen other cars were all hit one morning in the space of about an hour.

I was told that the thieves had a receiver that looked for the very weak fob signal from inside a residence and then amplified that signal to spoof the car into thinking the fob was near the door.

^^^ A good quality Faraday pouch will stop this.

They use a directional antenna and amplifier system. If you park on the street/drive-way any where near your house I would use an RFID blocking bag/box every night.

There is/was a YouTube video of someone stealing a Tesla out of a driveway by holding what looked like a large wire loop antenna between the house and the car and his accomplices opening the car and starting it.

They all jumped in and drove away.

It was all caught on the doorbell camera.

They may have had other equipment that was not visible.

quote:

Originally posted by WaterburyBob:
Is that necessary?

I know the signals can be intercepted if a receiver is near you when you push the Fob unlock button, but I've never heard of something that can scan an idle fob.
Or am I just unaware of a new development?

Modern key fobs are almost never idle.

It is constantly broadcasting so that you don't have to push the button to unlock doors or trunks. They pop out handles as you approach. lock doors as you walk away, and enable push button ignition

Thanks for all the explanation.
One more reason why I didn't want push button start and automatic door unlock just because I walked up to my new car.

Of course I'm assuming that the type of remote I've had for 25+ years to unlock the doors is idle until its button is pushed. If a fob is transmitting continuously, what sort of battery life does it have?

Look into copper foil used to shield electric guitar wiring. It typically comes with an adhesive on one side to make it easy to stick on.

Stewmac.com is one source. There are probably many others, and they are likely to be cheaper. Stewmac is good but not cheap.

Thanks for that, 9mm.

Neither of my cars have that automatic lock/unlock feature, so I didn't even know that existed.

From my understanding, which is limited...the container cannot have any gaps. The signal will leak out of the gaps.

quote:

Originally posted by WaterburyBob:
Is that necessary?

I know the signals can be intercepted if a receiver is near you when you push the Fob unlock button, but I've never heard of something that can scan an idle fob.
Or am I just unaware of a new development?

edit- I opened this window, walked away for a while, and came back and answered. I see a whole bunch of people beat me to the explanation!

Most of the newer ones transmit full time which allows you to interact with the vehicle without pulling the key out of your pocket. This also allows thieves to boost the signal so your car thinks the key is near or in it while the actual key is hung up in your kitchen.

quote:

Originally posted by sigfreund:
If a fob is transmitting continuously, what sort of battery life does it have?

Usually 3-5 years.

I found an irritating feature last night. I walked out to the car to get something from the trunk and it didn't open....I'd left the fob in the house...and then discovered that the doors had also locked.

At first I thought the battery of the fob was draining...but then I remember brushing against the front door handle when I got something out last night. On my Mazda CX-30, the doors lock when you brush the outside of the handle and unlock when you stroke the inside surface.

When the doors are locked, the fob has to be in closer proximity to the car...I'm thinking my fob was about 20-30 feet away. The Mazda also requires that the fob be in proximity to the car while driving away...so when you get out of range the ignition cuts out

quote:

Originally posted by 9mmepiphany:
<snip>
Modern key fobs are almost never idle.

It is constantly broadcasting so that you don't have to push the button to unlock doors or trunks. They pop out handles as you approach. lock doors as you walk away, and enable push button ignition

That seems unlikely to me. Transmitting takes a lot of power, but tiny key fob batteries last for years. I suspect it works this way:

The fob has a RECEIVER that constantly (or periodically) turns on to see if it detects an encoded signal from YOUR car. (You would have to be near it.) If so, it then transmits an appropriate command signal.

That’s my guess for NEW cars.

quote:

Originally posted by 9mmepiphany:
<<snip>> The Mazda also requires that the fob be in proximity to the car while driving away...so when you get out of range the ignition cuts out

That would seem to be the obvious answer to me for car makers to implement. If the fob isn't inside the vehicle when it drives away, the car shuts off. Period!

quote:

Originally posted by Pipe Smoker:

quote:

Originally posted by 9mmepiphany:
<snip>
Modern key fobs are almost never idle.

It is constantly broadcasting so that you don't have to push the button to unlock doors or trunks. They pop out handles as you approach. lock doors as you walk away, and enable push button ignition

That seems unlikely to me. Transmitting takes a lot of power, but tiny key fob batteries last for years. I suspect it works this way:

The fob has a RECEIVER that constantly (or periodically) turns on to see if it detects an encoded signal from YOUR car. (You would have to be near it.) If so, it then transmits an appropriate command signal.

That’s my guess for NEW cars.

True. I believe these attacks use retransmitters with powerful transmitters and sensitive receives. The retransmitter detects the signal emitted by the car, and broadcasts it out with a whole lot more strength so the key fob picks it up and responds from inside your house. The sensitive receiver picks up the weak responding signal from the fob, and transmits it with enough strength that the car believes the key is in the proper proximity.

quote:

Originally posted by 9mmepiphany:
then discovered that the doors had also locked.

That’s something else that I find absolutely incomprehensibly bizarre.
My new car also has several settings that include automatic door locking under some circumstances. As soon as I discovered it in the settings I turned it off so there’s never any automatic locking. Why anyone would want that is beyond me. If I can’t decide for myself when the doors should be locked and push a discrete button to do it, I shouldn’t be driving at all.