raphaelplm / enigma-machine Goto Github PK

The Enigma Machine is an encryption device used mainly during WWII. It also motivated the creation of the famous Bombe machine by Alan Turing and other researchers.

This project started as a programming exercise. After studying the engine of the Enigma, I decided to emulate its logic in a C++ program.

Enigma logic could be easily simulated with just a few lines of code, but this project aims to implement its mechanisms close to the real machines. This means that some elements of the source code may seem inneficient, but the overall goal is to maintain low levels of abstraction.

The enigma is a modular machine. This means that different modules (rotors and reflectors) can be attached in order to generate different patterns of encryption.

These modules are specified in two files:

• wirings.txt (Rotors)
• reflector_wiring.txt (Reflectors) reflector

The first step of the execution is to select three rotors. After selecting each rotor model, you'll be asked to select its offset. Then, you'll be prompted to select a reflector.

This process corresponds to the configuration step of a real Enigma. Rotors and a reflector will be inserted into the machine, and then the rotors will be rotated in order to generate an offset.

After setting up the machine, you'll be able to write a sentence, and get its encrypted version. It's very important to keep track of the adopted configuration (the model of the reflectors, the three rotors and its offsets), because this is what guarantees that the decryption step will produce the right output.

Currently, in order to decrypt a message, you need to restart the program :( Then, you have to setup the Enigma with the same configuration as in the encryption step. This means you have to select the same rotors in the same order, as well as the same offsets and reflector.

After setting it up, you just have to enter the encrypted message, and the original sentence will be then displayed.

Currently, the project has no Makefile. This means the following instruction must be executed to compile:

$ g++ enigma.cpp parser.cpp