Hello, everyone.
Let's say I bought two identical keyless remote access kits for my cars (generic aftermarket) and want to install them in order to open the trunks (2 cars).
Since they are identical and the cars are in the same driveway, would the remote fob from one car open the trunk of both cars? Can one fob interfere with another receiver? Assumed frequency is 433MHz.
If there is a chance of interference and I want to avoid that, could the oscillator crystals in set #2 be replaced with a different frequency, assuming that they both have replaceable crystals? Antenna length affected? I know that there are kits with "an external" antennas (just a wire) and imprinted on the PCB.
Also, this is an issue if somebody would walk up to my driveway and pop the trunk(s) with his "generic" 433MHz fob.
Thanks in advance.

 

It's not the matching frequency that matters, the FOBs would have to use the same codes.

 

So, each set has its own "unique" code that doesn't interfere with another set? And two sets (the same model and manuf.) won't interfere?

 

So, each set has its own "unique" code that doesn't interfere with another set? And two sets (the same model and manuf.) won't interfere?

You usually need to 'pair' the remote with the controller. This pairing generates unique codes (some pairing code chips are better that others) for each remote or set of remotes for only that controller during that pairing process.

 

OK, I understood - the pairing is unique for each set. Thanks. Now I can sleep better.

 

OK, I understood - the pairing is unique for each set. Thanks. Now I can sleep better.

Don't sleep too soundly or keep anything valuable in the car, most of the codes on the cheap remote fobs can be easily broken.

https://www.ndss-symposium.org/wp-content/uploads/2023/02/vehiclesec2023-23037-paper.pdf
Enhanced Vehicular Roll-Jam Attack using a Known Noise Source

Abstract—The traditional vehicular roll-jam attack is an
effective means to gain access to the target vehicle by jamming
and recording key fob inputs from a victim. However, it requires
specific knowledge of the attack surface, and delicate tuning
of software-defined radio parameters. We have developed an
enhanced version of the roll-jam attack that uses a known noise
signal for jamming, in contrast to the additive white Gaussian
noise that is typically used in the attack. Using a known noise
signal allows for less strict tuning of the software-defined radios
used in the attack, and allows for digital noise removal of the
recorded input to enhance the replay attack.

 

Now, I can't sleep!

 

Wireless Convenience == Inherent vulnerability

 

Now, I can't sleep!

Don't worry about it. The odds are in your favor in a safe neighborhood. Why steal your car when you can jack one with a USB cable?

 

To get an idea of what is going on, this talk by Samy Kamkar (@samyk) who we are fortunate to have as a member here, albeit not very active, is probably the preeminent authority on wireless hacking of cars, remote controls, and related topics.

He has many talks at conferences, and lots of material on his website.