Unexpectedly, my paper got some press attention. @jswatz_tx found it and wrote a short piece in the NY Times.

And then locksmiths freaked out. I mean completely lost it. They were very upset, not so much that a very common lock design had a basic security flaw, but that an "outsider" found it and had the poor moral character to make it public.

I started getting weird death threats. They doxed me ("let's see what kind of lock the bastard has on HIS house")

2/

A trade publication called The National Locksmith ran monthly guest editorials in which prominent members of that profession were invited to denounce me. My favorite quote, from a locksmith named Billy Edwards, who had written a book on master keying, and who took my paper rather personally.

3/

I should point out that master keying was about a century old at the time, and while the mechanical details weren't secret, locksmiths tended to regard the inner workings of locks as "restricted knowledge", rather like a medieval trade guild. I didn't understand this.

What took me by surprise was how different the physical security wold's attitude was compared with that of my community, where the ethics of discussion of vulnerabilities has long been essentially settled in favor of openness.

4/

Essentially, their argument was that this would be a huge pain and expense to fix, and so we are all better off just keeping it on the down low. And that kind of worked, for about a hundred years, until more open communities - like computer security research - started looking seriously at locks (as both metaphors and as interesting mechanisms in their own right).

I see their point, even if I personally reject it. But in the age of the Internet, you just can't keep this kind of stuff secret.

5/

Anyway, my intent in looking at locks and publishing my paper wasn't to disrupt the lock industry. I believed, as I still do, that mechanical locks and physical security have quite a bit to teach computing, but also that the abstract techniques of cryptography and computer security can illuminate weaknesses that are hard to see when looking at systems in strictly mechanical terms.

My attack is intuitive and obvious to cryptographers, but rather subtle without our field's tools.

6/

I never did reach a truce with the locksmiths. A couple years later, I met Billy Edwards, the author of that editorial denouncing me, at a trade show, and when he learned who I was he refused to shake my hand and asked me to leave him alone.

I wish he had seen things differently, but I can respect that he was coming from a place of genuine concern, even if I think his approach was wrong.

To this day, I worry that I'm pretty screwed if I get locked out of my house.

7/7

NB: While I never intended to piss off locksmiths with my master keying paper, I did write a followup a couple years later about safes and safecracking, partly out of spite.

mattblaze.org/papers/safelocks…

TL;dr: We can learn a lot from safes and safe locks, and the frameworks of cryptography and computer security are applicable there, too. The fact that our learning about this subject makes people in that industry upset is just a bonus.