Inside the Enigma

Introduction

Press a key on an Enigma and a current runs through the plugboard, three rotors, a reflector, back through the rotors and out to a lamp.

Before the current flows, the right-hand rotor turns. That single fact means the cypher changes with every letter — and made the machine look unbreakable.

Key ideaEvery keypress steps the rotors, so the same letter is encyphered differently each time.