The Theorem that Won the War: Part 1 – Enigma on Paper

In 1923, the firm of German engineer Arthur Scherbius (1878–1929) began selling a machine that could encrypt messages automatically. Marketed as Enigma, it was soon adopted (and adapted) by the German military, and by the outbreak of World War II, it was used for almost all important German military communications.

To understand the mathematics behind Enigma, it helps to have an Enigma machine. Unfortunately, most of the remaining machines are in museums, whose curators don’t take too kindly to handling their exhibits, so we’ll have to make do with a mockup. Online Enigma emulators are available, but to understand the mathematical details, we’ll set up a simple “paper” Enigma to analyze key points. We will do this in two parts, pausing to take part in some specific activities along the way.

• Part 1.1: Rotors
  • Activities for Part 1.1
• Part 1.2: The Enigma Encryption
  • Activities for Part 1.2