It’s a tough job to make public-access interface systems, such as the keypads of ATMs, which can stand up to all forms of ‘use’ (Including attack by blowtorches and portable roaddrills- I’m not kidding).
Today’s invention is an adaptation of the well-known sliding tile puzzle which allows ATMs and other public kiosk systems to be simplified and made more robust. Each authorised user would be equipped with a puzzle, perhaps the size of two adjacent credit cards. The tiles would be movable from behind, whilst the user held the puzzle in front of a camera lens, located behind a small area of armoured glass.
Different configurations of the (clearly marked) puzzle pieces (of which there are 16! for a 4*4 grid) would be interpretable as instructions to the kiosk eg “withdraw £10”. This would allow the guts of the device to remain almost completely inaccessible to would-be thieves and vandals and the code embodied in the arrangement of an individual’s pieces would make their interpretation by any shoulder-surfer almost impossible.
It would also shorten queues, since people would array their pieces on approach to the machine. Each time a puzzle is used, the pieces would be slid a little away from their last-used configuration, making stealing someone’s puzzle a waste of time.