Lock puzzle

Lock puzzles are puzzles consisting of a lock with unusual or hidden mechanics. Such locks are sometimes called trick locks, because opening them is like performing a magic trick. A matching key may or may not be used in this trick.

Lock puzzles have a long history. Chinese jewelry boxes often contain trick locks and hidden drawers. An example of such a box is an integral part of the plot of the movie Shanghai Knights. Clive Barker has written a number of horror stories (including The Hellbound Heart, which was made into the movie Hellraiser) centered around Lemarchand's Box which appears to be such a puzzle box but in fact opens the gates to Hell when manipulated.

Other lock puzzles stem from the necessity to invent secure locks in the Middle Ages.