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Comment by miniatureape | Hacker News Reader

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miniatureape·

A made a little “secret knock” authentication demo.

Shave and a haircut is obviously the secret knock used in the demo

https://miniatureape.github.io/prohibition/

(Nb: I’m sure this doesn’t work great on some devices)

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Fun! Over a decade ago, my boss and I added a secret knock using Shave and a Haircut just like this to our wayfinder product, a large touchscreen app used on trade show floors.

It’s how we got into our admin to maintenance them at the shows and was useful if something was wrong with the onscreen keyboard (or we didn’t have our own keyboard to attach).

I used it for a silly credits screen in football trivia game - summer 2002 I could knock on the screen of a many pub trivia machine to make it show my name :)

It just always says scram no matter what I do, I can record a single knock and it will still say "scram". Latest Safari on latest macOS.

I couldn't get it to pass on my phone, but "scram"/"get out of here" is equivalent to a password rejected/401 response. A single knock does not match the expected pattern, so you would expect it to be rejected.

No, there is a recording function that is supposed to let us in (I think?), but I don't know how

I had an issue, but I figured it out. The rhythm is not the same as the one on the wikipedia page - which I was already familiar with. After looking at my recordings I realized I was playing it straight, but the default knock recording has a swing/triplet feel.

straight: DAA DA-DA DA DA, DA DA

swung: DAA DA D-DA DA, DA DA

I hope my highly rigorous notation is helpful here

edit - in hindsight this has nothing to do with your problem

I can't use it on Edge, I tap tap, record, tap tap, do everything I can, but its Scram every time

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