Today’s invention is a simple way to improve the security of a lock-and-key mechanism.
The door, or lid, containing the lock would be equipped with an array of identical keyhole plates, only one of which would have an actual lock behind it. All others would be decoys. The plates are cheap to apply and delay the actions of anyone speculatively trying to pick the lock, or of someone who has somehow obtained the correct key.
In addition, a special lock mechanism might be used (eg in a Yale-type lock) in which any attempt to turn or vibrate the internal cylinder, without first having fully displaced all the pins (in the right order), would cause an internal mousetrap-like device to snap shut on the lockpick or skeleton key, making its withdrawal impossible. This might also be used to activate an alarm.