I read that if you lock yourself out of your remote control locked car, that you can have someone who has a spare key beep theirs into their cell phone while you aim yours at the door.
That would mean it’s an audio signal?
Or that radio signals can be replicated by cell phones?
Anyway, if it’s audio, couldn’t a crook just wait at the parking garage, taping every remote when people go home. And return the next day to play back the tape and pop open the doors and trunks?
It’s not the sound. Those thing use infrared signals which you can duplicate with a computer that has an infrared reciever and the appropriate software.
OK, you’re both mistaken.
The standard remote car lock is RF based, not infrared or audio.
The ones I’m familiar with transmit a low-powered radio signal at 300-500 MHz with digital codes embedded in the signal. The digital codes are where your security lies. There are billions of combinations of these digital codes.
As far as a cell phone being able to unlock your car, Snopes says no. And that is exactly what I was going to tell you.
Actually, I do believe that mine uses infrared, as I see no (at least exterior antenna) and it does have a filter just like those you can see on TV removes.
But anyway, even if it does use RF (which I do believe that some do, since I’ve seen friends opening their cars from a long distance while mine has to be pretty close) it can also be fake with a computer and the appropriate software if you can get a sample of it. But yes, by trial and error it might take a while.
What do you mean “does have a filter”? An IR LED like TV remote?
Do you have to point it at the auto?
Will it open the lock even if in your pocket or pointed away from the auto?
Nevermind. A knowledgeable car thief can open the door and barring a micro-chip equipped key can unlock the steering wheel, start the engine, and be out of sight in a few, (3), minutes at most.
No cites but I read an article in the past few months that claimed that some researchers at a university in the U.S. had developed a device that cracked the code. Fortunately, they are honorable members of society and are sharing their findings with the auto makers so that they can improve security.
Cause for worry? Not really at this point.
However, it just shows to go you that as soon as you devise something that you think is bulletproof, someone will develop a better bullet.
A) The average car thief is not knowledgable about cars
B) It depends on the car and security system. There is no way in hell a car thief could get my car started in 3 minutes without an authorized key that has been programed in to the computer memory. Tow it away yes. Get it started and drive it away? No way. Hell I could have a duplicate key cut, and give that to the guy, and if it had not been programmed into the computer memory he still would not be able to start the car. Not in 3 minutes, not 30 not in 3 days.
There was an episode of Numb3rs that addressed this topic.
On some of the early models, it was possible for someone to grab the codes using a “sniffer” (i.e. a device that records the signal and then will repeat it). However, the car makers quickly fixed that problem (don’t know about the low-end aftermarket folks, though), by using the scrambled codes that change every time you use the fob. The odds, of course, of your car being snagged by a sophisticated thief are next to non-existant, unless you own some highly desirable car (there’s an apparently thriving black market in stolen cars in Asia and the Mid-East). Otherwise, as has been said, it’s going to be towed out of there, taken to a chop shop, and stripped for parts.
So close, yet so wrong. The linked article is on the RFID tags in the igniton keys and items like a Mobil speedpass
This thread on the other hand is concerning the security of remote keyless entry systems.
Any decent authentication system should be resistant to replay attacks through the use of two phase authentication or something similar.
There were reports about a thief using one of those watches that can control TVs to open cars - he would test drive the car, program his watch with the signal, then come back and drive it off. That was a long time ago though (assuming it was true), the signal changes every time you press the button now. Also, I believe radio hsa replaced IR as the main way of opening cars.
So assuming for a minute that he A) could program his watch to the IR unlock signal, and B) do this without making the dealer employee wonder what the fuck he was up to, I have a rather simple question.
How did he unlock the steering column and start the car? I haven’t seen a watch that can do that. 
The weak point for stealing cars with the “correct” key is criminals social engineering dealers into cutting them the right key.
Was it possible a few years back? Heck yeah.
Would it work today? No clue. Hope not.
Here’s How Stuff Works article on them.
Unless your car is fairly old it has to be RF. 100% of systems made today are radio frequency. My brother owned an old Eagle (mid 80s) which had the only infrared system I’ve ever seen. It had a little black dome receiver above the rearview mirror. Didn’t work very well either, being line-of-sight.
According to the HSW article above, modern 40-bit systems have trillions, with a ‘T’, of possible combinations.