In winter 2015, I visited Bletchley Park, where I saw real Enigma machines.

I came home and decided to build a software one in Java, and make it an exercise with my second year computer science students.

Note that it was not a cryptographic exercice, but a software engineering one. It was tested against virtual enigma machines found on the internet (like this one) on sample texts with basic settings.

The students got fun. Me too.

I was able to find many information on the internet (e.g. the mapping of each rotor and reflector).

The GUI is basic: you type a letter on the keyboard, and a letter is highlighted on the GUI (the letter is also stored in a textfield). There is a known bug in the GUI: the rottors are "eaten" by the machine (i.e. they do not appear again in the rotor box when replaced by a new one).

I make it available for education purpose: I am happy to get feedback on that design. Note that some comments are still in French.

The design is simplified: the rotors cannot be shifted, and there is no plugboard.