Author Options:

Safety of your garage door or car remote... Answered

No time and no pics for a proper Instructable, so I just put out some word of warning ;)

Around here bad people take advantage of the fact that a lot of new houses have the garage right next to the house.
With these you usually also get a door so when you park your car you don't have to get out of the garage again.
All controlled by the press of a button on the remote...
Some fancy guys got a device working similar to the IM-ME Open Sesame hack a few years back.
But unlike the original author the new guys found ways to make money by providing working "universal garage door openers" on dubious websites.
Problem with the new model is that it not only fakes a remote with dip switches but also the newer models with so called "rolling code", "intellicode", "changing code" and so on.
The old remotes with dip switches should actually by phased out years ago by any owner who values his stuff...
But the new models are still deemed secure and next to impossible to hack - well if you trust the advertisement...

How does the code hacking work?
The old dip switch models allow for a maximum of just over 4000 different codes and come in just 3 or 4 frequency bands.
No real problem for anyone with basic electronic and coding skills to hack these - as shown with Open Sesame.
The new models all use a so called rolling code, here the remote and opener are paired through 32 bit of ID code and an encrypted part that changes every time.
Both remote and opener calculate the next code once a button was pressed or a code received.
To overcome reception problems the base usually calculates the next 256 codes in advance - and that is the entry point for bad boys.
The illegal device scrambles the frequency detected while storing the code received by the orignal remote.
As the door did not open the owner will try to press the button again.
Still scrambled to opener does nothing - until the device sends out the first recorded code!
Now the owner can drive in and is happy.
Of course he still needs to close the garage - again all is scrambled and the code stored as before.
You see where this is going....
It is even possible to set the amount of required tries to capture, so in theory a bad guy could get the next 10 or codes in advance for use once the owner is gone out...
Worst thing however is that these illegal devices not only open garage doors but also cars as a lot of them use similar systems for their remotes - up to the point of starting the car with it.
Took me only 2 hours with Google translate to find a website outside the usual search results that offers these "gadgets", along with WiFi and cell phone jammers, credit card copy devices and more things I don't want know about...

What can you do to protect yourself?
First check what type of remote your system uses - if there are DIP Switches than replace the remote system or the entire device in favour for something more secure.
If you already have a rolling code model that you are far better off but sadly no longer totally safe here.
A lost remote should not only be replaced but the old one removed from the system as well - you never know if you just lost it or someone took your remote ;)
Alternatives exist, especially if you are not afraid of doing some open heart surgery on the electronics of a garage door opener.
You can add a WiFi module and use your mobile phone to open the garage - search Google if you like the idea ;)
Another very neat way is using a second transmitter that keeps the relay for activating the opener from working.
This can be anything from a BT module paired with your phone or cars BT system over a keycard to numberplate recognition cams.
A good system also allows for a "holiday mode" or similar.
Here you can set this mode with one remote until you deactivate it with the same remote the system will not react to anything.
Great if you leave the house for more than a day or two...
As a last resort you can always get a big and angry dog to sleep in your garage....

What if you are renting or a bit limited with the electronics and soldering skills?
Not all is lost if you can accept a second remote for added safety.
These days you can get plug in converters for your mains voltage outlets that work with a remote control.
Unless they use Infra Red for this they are great to disable your opener.
Simply plug it in where the power cord for the opener is and then plug the cord into it as well ;)
Now you can fully shut off the opener with the press of a button and only if the power outlet is switched on the opener will work.
If in doubt you can use a double outlet adapter an extension cord and a night light to indicate wether or not the opener has power.

Ok, and what about the door lading from the garage into the house?
Well, of course keep it locked and if you are home also keep it locked.
At least this way you have some extra time in case someone tries to enter through your garage while you are sleeping ;)


The forums are retiring in 2021 and are now closed for new topics and comments.