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Comment by virtue3 | Hacker News Reader

I think if you have enough replays you can deconstruct the rolling code. Not sure.

Also there are ways to desync/resync your key so you might be able to “add a key” with the flipper with certain firmwares.

Cloning the current key and using it can desync it from your car. Super annoying. Be careful

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I don’t know exactly how the rolling key works but wouldn’t it be kind of like having a secret stored in the key that’s needed to generate the next code? If it’s designed properly, recording a few thousand codes shouldn’t tell you anything about the next code, just like you can’t deduce private keys by looking at a few thousand encrypted files. I have no clue if that’s really how it works, so I would be happy to be corrected if my mental model is wrong here.

Basically yeah. You'd need millions of replays to even have a chance. Cracking basic wifi back in the day required a couple days worth of sniffed packets. I'd imagine this is similar, if there is in fact a way to do it.

Rolling code protocols like Keeloq can be broken pretty easily (apparently).

> If it’s designed properly,

That phrase is doing a lot of heave lifting there...

(This is only what I've read, but as i understand it many rolling code keys can be broken by recording three button presses while the keyfob is out of range of the car, then brute forcing the seed.)

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