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Rights Amplification in Master-Keyed Mechanical Locks (2003) [pdf] (mattblaze.org)
46 points by wglb on Aug 2, 2022 | hide | past | favorite | 11 comments

Matt recently wrote a tweet thread about this paper and his history with a University Locksmith ... https://twitter.com/mattblaze/status/1553244850304290817

I remember reading this when it was published, as I was living in a college dorm at the time and strongly considered using this method to produce a master key. I didn't, because I couldn't think of anything I'd want to do with the master key once I had it. But I enjoyed knowing that I could make one if I'd wanted to.

I had plenty of legitimate uses for a master key, but I didn't make one because once 2 or 3 people know you have a master key you get blamed for every single misplaced object in the whole damn dorm.

You don't know that you could make one until you do make one.

That isn't necessarily true. There are a ton of things that I know how to make and that I'm sure that I can make but which I haven't made yet.

Every time I see an F1 race and see all of the crypto.com ads, I can't help but picture Matt Blaze spending millions of dollars to advertise his blog.

The difficulty of this attack is definitely in producing so many test keys. I imagine that it might not be much easier than disassembling the lock.

You need one test key per pin, so on the order of 7 keys; that's not so terrible.

Don't you need (up to) `N cut depths - 1` keys per pin? E.g. if there are 4 possible cut depths for a pin, and your key has depth 3 on pin 1, you need to (potentially) test depths 1, 2, and 4 -- and if none of them work, your key shares a depth with the master key.

Oh, you could re-use the same test key if you start at the higher depth, of course.

Is this available in a readable form?

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