Duration: 60 hours
Team Members: 3
Skills Applied: Arduino IDE (C), Circuit Assembly, Logic Gates, Soldering, SolidWorks
Tools Used: Arduino, 12V Power Supply, Miscellaneous Electrical Components, Rabbit Laser Cutter
Background
The Enigma machine is an encryption device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military. The Enigma had an electromechanical rotor mechanism that scrambles the 26 letters of the alphabet. In typical use, one person enters text on the Enigma’s keyboard and another person writes down which of 26 lights above the keyboard lights up at each keypress. If plain text is entered, the lit-up letters are the encoded ciphertext. Entering ciphertext transforms it back into readable plaintext. The rotor mechanism changes the electrical connections between the keys and the lights with each keypress.
More can be read here.
Our Project
This project is a functioning model of the rotors in an Enigma machine from the World War II era. Our project specifically uses clear acrylic and LED lights to visualize the path which the electrical current would follow, highlighting the locations where the coded letter would be encrypted within the rotors. To hone in on the specific function of the encryption path in the rotors, we simplified the rotating mechanism for each individual rotor from a system of ratcheting mechanisms to stepper motors. As the rotors rotate relative to each other, the path within the rotors changes, resulting in a different encryption pattern for each time the circuit is run.
Within the rotor, there are a series of electrical wires, connecting one part to another corresponding color (i.e. Blue light corresponds to Red light on the other side of the rotor). This hard connection is part of the encryption process, where each rotor is hard wired to visualize the change in the electrical path. The rotors are made from clear acrylic to allow visualization of the electrical connections within the rotors. To continue the electrical path, we used copper tape pads on the edges of the rotors, with one side built up with a balloon interior to allow flexibility to maximize conductivity between the two pads.
This project sought to simplify the rotors scramble system of the enigma by using stepper motors instead of a ratcheting system, and with only 6 LED paths. By utilizing LED strips, we were able to make separate rotors which show the scramble between input and output of each rotor. By using copper fasteners, we were able to conduct between each separate rotor, allowing the possibility of changing electrical paths with rotations.
Documentation can be seen on the next page.