Run an Enigma Machine Visual Simulator on an Arduino

Enigma machines are likely the most famous cryptographic tools ever developed. While they were originally designed in the early 20th century and were used for commercial purposes, they’re most well known for their use by Nazi Germany in World War II. Through spying and brilliant mathematical work, they were cracked by the Allies time and time again throughout the war, which makes them a very interesting part of history. Now you can run your very own Enigma machine visual simulator on an Arduino.

An Enigma machine is a very complicated electro-mechanical cipher that relies on a series of rotors to take a input letter and convert it into an output letter. Each rotor can be turned to different positions, and the combination of rotor positions and plug wire positions— the encryption key — results in unique ciphers. Those rotors create complex and irregular electric pathways for each letter typed, which is why Enigma machines were so difficult to crack. They don’t simply produce an offset cipher, which is trivial to break, but rather a very robust series of ciphers for each letter. They were really only defeated through spying, and because of a lack of operator diligence.

Thanks to Mark J Culross, you can now use an Arduino to experience for yourself how an Enigma machine is operated. To do that, all you’ll need is an Arduino Uno and a 2.8" TFT touchscreen LCD shield from Adafruit. All you have to do is flash Culross’s code to the Arduino, plug in the LCD shield, and get started. The display will show a graphical representation of an Enigma machine, and you can choose from various specific models with different numbers of rotors. You can even configure the electrical pathways of each rotor. Then you simply set your rotors, and start generating encrypted messages — and then decrypt them!