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Our house and a few other share the same gate, which is opened remotely by a 433Mhz transmitter.

Unfortunately, we only get one remote per house, and we have two car. The company operating the gate charges almost 100€ to get another key, I thought it would make a fun project to try to clone our existing remote.

I own a RTL-SDR dongle, and I captured the packets sent by the remote. It seems the gate uses a rolling-code algorithm, as the transmitted code changes after every press on the remote.

66 bits are transmitted, 32 are changing every time and 34 are constant, which seems to indicate it is using KeeLoq according to the rolling code Wikipedia page

So I was wondering if there was any possibility of cloning my remote?

My main assumption was that if I record enough presses on my remote, the transmitted code would cycle back to the first one, so I would have all the different possible codes.

Is this possible? Or would there be too much codes before cycling back to the first one?

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  • \$\begingroup\$ 32 + 36 = 68 (not 66) \$\endgroup\$
    – Andy aka
    May 18, 2014 at 19:12

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Maybe, if you recognize the chip, you can extract the code. But there might likely be another issue that is difficult to overcome.

A bona fide 2nd "remote" would be recognized by the system and be seen as having its own address (and sequencing) by the receiver. This is because it would be impossible to keep two identical remotes in sequence - the new one would soon be out of sync with the original remote and this would screw up things entirely. The new 2nd remote would be dealt with differently than the original remote normally.

This is the same problem in cloning a 2nd remote.

Hey, you can afford two cars, pay for it LOL (yeah I know it's fun)

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  • \$\begingroup\$ Thanks. This idea seems more and more impossible to do indeed... By the way I don't actually own 2 cars, I have my own car and live with my parents :) \$\endgroup\$ May 19, 2014 at 5:32
  • \$\begingroup\$ @AlexandreBlin LOL \$\endgroup\$
    – Andy aka
    May 19, 2014 at 8:27

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