I was recently at an airport, and while waiting I noticed a "staff- only" type door with a numerical keypad lock. A closer look at the lock showed that it was almost entirely wear-free except for the "1" and "9" keys. Furthermore, there was clearly a lot more wear on the "1". From this, it's not difficult to dramatically cut the number of possible combinations that open the lock. Add in human tendencies such as laziness, and I thought that there was a 50% chance the combination was 1119. I wandered over and tried. I was right, and illicit access to a cleaning closet was mine!

Such factors defeat the purpose of the lock, which is, presumably, to deny the public access to mop buckets. So what can we do?

Lock manufacturers can recommend that customers change the combination frequently, but it won't happen. So, after the lock is made, it's put through an additional process that randomly distresses 2-3 keys. Then, in service, it will be a lot more difficult to determine from wear patterns what the lock combination is.
-- bs0u0155, Jul 07 2022

for a1 (Secure Shuffle Keypad) https://www.allgood...ure-shuffle-keypad/
" Randomised key locations are generated and shuffled to new positions each time the user uses the keypad." (I am not commenting on the security of this lock) [Loris, Mar 06 2023]

How about the wrong number scrawled someplace in sharpie? You input it and it blows up.
-- doctorremulac3, Jul 07 2022


//How about the wrong number scrawled someplace in sharpie?//

Nice touch. Piece of old painter's tape, faded, maybe even crossed out, but with green pen, so it's mostly visible. We could branch out, a door that LOOKS like it's propped open with a wad of paper, but actually isn't, removing the paper makes the lock explode.
-- bs0u0155, Jul 07 2022


Needs more explosions but [+] anyway
-- pocmloc, Jul 07 2022


There are "touch screen" keypads that randomly display the digits, so you aren't pressing the same spots all the time.
-- neutrinos_shadow, Jul 07 2022


//Needs more explosions but [+] anyay//

Ditto
-- doctorremulac3, Jul 07 2022


I like it!
-- 21 Quest, Jul 07 2022


@doctorremulac3 Perfect glitter-bomb application. Got photo, virality, chagrin. Film at 11.
-- minoradjustments, Jul 11 2022


// There are "touch screen" keypads that randomly display the digits, so you aren't pressing the same spots all the time. //

[neutrinos_shadow], have you got a pointer to something like that?
-- a1, Mar 06 2023


// There are "touch screen" keypads that randomly display the digits, so you aren't pressing the same spots all the time. //

[neutrinos_shadow], have you got a pointer to something like that?

(Edit - [Loris] - thanks for the link)
-- a1, Mar 06 2023



random, halfbakery