Re: Faraday bags and other scarey things (2023 Update)

Anyone with more than a couple of brain cells knows about keys in a faraday cage.And probably all in this group...

Well, it's not *simply* false. it's false in the case of cars some, like the guy on NextDoor, describe cryptically as "pushbutton" cars. My car's fob and the car have lots of pushbuttons too.

Last Feb to June I rented a car that was only a year old and I've already forgotten how unlocking the door worked, but it had a little add-on keypad and 4 numbers had to be entered to start the car. So that would defeat this method of stealing cars. But I know American cars, or non-rental cars, don't have such things.

It seems almost like it's worth not buying a car like this. Even if you live in the Yukon, on a farm 20 miles from town, where thieves never go, if you go to town and don't use the Faraday bag or something, and someone likes the car, can't he see the owner get out of it, follow him and amplify the signal and while the owner is walking one way, walk the other and steal the car?

Nope, not with the best keyless systems.

When we get home, our keys go in a Danish Butter Cookie can. Those are pretty good shields.

I bet keeping the fobs in an open top brass bowl would also work, by being a shorted turn close to the fob's antenna loop.

Back when we worried about the RFID chips un US passports being read from a distance, I would but a piece of 0.003" brass foil in the passports book. If I forgot to remove the brass sheet, the US Passport Control folk could not read the RFID chip. They never gave any grief after I removed the sheet and it scanned OK.

Joe Gwinn

Yep. But those bags have their use too -- you car can be stolen when you e.g. park it at a grocery store and come inside. The good practice is to put the keyfob in a Faraday cage protection bag every time you leave it. Those are not big boxes and easily fit in one's pocket. Something like this:

Or you could just drive a car with an actual key, like my 2012 Mustang convertible. ;)

Cheers

Phil Hobbs (And yes, it's pointless locking a convertible--if only I could convince my insurance company.) ;)

We have old fashioned cars with RF fobs that transmit when the button is pushed. I don't think the RF relay cheat works with them.

The retranslator makes a faraway fob to appear NEAR your car :) No intelligence required, just receivers/amplifiers/transmitters.

When car responded and allowed the perp in and start the engine they insert a key pairing device in the vehicle OBD port and in ten seconds or so marry their own keyfob to the vehicle. Then they have a properly working keyfob in their hand that vehicle recognizes as its genuine one and nothing else needed anymore.

You can purchase a set of e.g. Lexus keyfobs and that device for mere $100 or so from many places on the Net. This allows the perps to give a stolen car to a prospective buyer with a fully working set of genuine keyfobs as if it was a fully legit car, not stolen. The thing is reusable so they can reprogram fobs again or use the OBD plug on another set. That is if they don't want to bother with a hacked full Techstream that allows to do anything including pairing the fobs.

There is no "best keyless system", the thing is FUNDAMENTALLY flawed.

I know that it doesn't. And even recording what happens when the owner locks the car doesn't work with a rolling code system.

It should be something very high resolution to distinguish e.g. 10ft. from

100ft... Then, the keyfob should be blazingly fast as the roundtrip time includes the fob response time that is almost certainly several orders of magnitude more that signal roundtrip time. That makes a whole bunch of tricks possible as it is not THAT fast.

The very simple and almost bulletproof solution is to have a button on a keyfob that turns it on and off as needed. However that doesn't fit that braindead idea of "hands-free". So Faraday bag substitutes for that button.

If you are going to do all that BS, it's better to just have a key fob that doesn't do anything until you push a button. Then no way to defeat it, without all the silliness.

I wear my key on a carabiner hooked to my belt loop. A miniature version of the biker's wallet. Works fine, but it does leave my car susceptible to being stolen if the thieves have the proper tech. Good thing they tend to avoid Teslas on general principles. There are much easier cars to steal, like my 2005 Tundra pickup.

So I guess the thieves don't know your theory. Someone tell them they can't steal the cars they're stealing.

As long as that delay is fixed, accurately, it can't be removed and the distance can be found.

Even if it is a poor substitute. It shouldn't be needed at all. How would you feel if you found out your bank's security depended on the manager remembering to use something equivalent to the baggie for the vault? I'd get my safe deposit box out in a hurry.

So now you have to wear a wrist watch to unlock your car? Electric cars don't really have start buttons. Mine is "started" by stepping on the brake pedal. I like the sound of the engine when it revs up! lol

Why worry about tech for cars that won't be made for more than another ten years or so?

In theory, yes. However considering the distances involved the required resolution seems to be far out of reach. Especially with the keyfob requirement of being small and not requiring battery replacement every week.

Of course we want everything and at the same time in the same tiny device. However, life's a bitch and one have to make compromises.

It is also worth remembering that those making living from breaking security systems are not stupid. As a matter of fact, they are probably the brightest minds, top of the crop. And another thing is that there are very few working on designing those security systems while the number of trying to break them is essentially unlimited in comparison.

It is all true. However, I'm not talking about a button to activate the fob BRIEFLY. It is turn on/off switch. You turn the switch on (pull the fob from the Faraday bag) when you are near you car. You can put it in your pocket and keep it there while you are driving -- there is little use of recording RF traffic or whatever so that can't be used to steal your car later on. Then, when you leave your car and have it locked and armed you turn the fob off (put it in the Faraday bag) so nobody could use a range extender to steal your car.

Ah, that is not a solution... You can use, e.g. a "security button" by applying it to a pad on your vehicle as well. It is just an electronic version of a good old mechanical key...

I wonder why we are not there already... However, in case everything else failed my Lexus LS460L has a mechanical emergency backup key :) It is a part of that keyfob assembly -- you can pull it from the fob and open the car with that mechanical key. That is an ESSENTIAL feature that MUST be present. Just imagine that your car's battery died. What are you going to do? The battery is under the hood so you'll have to open it to get to that battery. The hood lock is mechanical but its lever is INSIDE the car and you can't get into the car to open the hood to replace the battery because the working battery is required to open the door to get to the hood lock lever to get to the battery...

Not in theory, this is a simple thing to measure. It's not the keyfob that needs to do any heavy lifting. A crystal oscillator sets the time base. From then on it's just a matter of ticking off the time for the delay. You can measure a waveform accurately to a small fraction of a cycle. This is the basis of many time codes.

None of this is remotely relevant.

Nope. I have a LiIon/SuperCapacitor booster inside the car (actually in the trunk but I can retrieve it from within the car even if the trunk is locked). You put the booster's alligator clips across the battery and after some time (minutes) the supercap is charged enough to give your car enough power to start the engine. Once engine is started your alternator takes care of running everything else and charging the battery.

That's a different story.