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A comment on Almost one in 10 people use the same four-digit PIN. Parent comment

Re:Almost one in 10 people use the same four-digit PIN by kqr on Tuesday January 28, 2025 @05:15PM (#42858784)
And even if the number is randomly generated, many devices accept any string of digits that end with the correct four digits. Pressing "12345" actually tests both codes "1234" and "2345".

I'm sure there's an optimal sequence of keypresses that tests all 10000 codes in something like 30,000 keypresses rather than the naive 40,000.

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Re:Almost one in 10 people use the same four-digit PIN by quesera on Tuesday January 28, 2025 @08:19PM (#42860293)
Also true of those old "lockbox" key lockers that real estate agents use to "protect" the keys to your house.

This made me uncomfortable when I was selling a house, so naturally I wrote some code to generate a string of digits that would cover the full solution space most efficiently.

Armed with this "master key", I had the lockbox open in negligible time. Honestly I think it was just a few minutes, and I was about halfway through the string.

This let me put the key out only when a showing was happening, and I brought the lockbox to the closing, which baffled the real estate agent.

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Re:Almost one in 10 people use the same four-digit PIN by speq on Wednesday January 29, 2025 @06:36AM (#42863818)
Yes, there's some solid theory behind it:

https://en.wikipedia.org/wiki/De_Bruijn_sequence

It seems that you can do it in 10003 key presses. Calculation for this this exact example is in the Wikipedia page.

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