This is just like the games we used to play as kids, on tree-houses with really sinister clubs. ‘Groupism’ was the way of life back then and rivals often popped in to spoil the fun. So we had a secret knock that matched the beats of ‘Hickory Dickory Dock’. It worked. No one but club members could understand it. Similarly, the Knock-Detecting Door Lock manages to keep your door sealed, with a secret lock that opens up only after it detects someone knocking in the exact pattern that has been recorded.

Now it’s up to you to pick a simple, yet, hard to guess pattern. Avoid hip-hop tracks since they are pretty similar to regular knockings. Also, avoid living near woodpecker-inhabited areas.

[Techeblog]