This simple Enigma machine simulator has been implemented to familiarise the audience of my lecture on Marian Rejewski's Enigma breakthrough of 1932 with the machine's mechanism.

Click any letter on the keyboard and observe the lampboard. One of the lamps will light-up. Hold the key to trace the path the electric current must travel from the keyboard to the lampboard.

A subsequent pressing of the same key will (usually) cause a different lamp to light-up. The current is passing through ‘rotors’—wheels connecting 26 electrical contacts on the left side to 26 contacts on the right by a permutation. Every key-press causes the rightmost rotor to move one step. The middle rotor is pused one-step forward by the rightmost once every 26 steps, etc.