Enigma Machine

This project contains an enigma simulator, as well as a decryptor.

Requirements

1. python 3.9.x
2. pip3
3. Python Modules:
    a. Flask
    b. sys
    c. os

Installation

In case you don't have a python installation, you can install it using:

1. Linux:

sudo apt-get install python3 python3-pip

2. Windows: Head over to https://www.python.org/downloads/windows/ and follow the instructions there.

The os and sys modules come along with your python installation, but you'll have to install Flask. This can be done using:

pip install flask
or
pip3 install flask

Get this project by git cloning this repository using

git clone https://github.com/gall1frey/enigma_decoder

Usage

GUI

The project comes with a GUI. This is purely for conceptual purposes, to show how an enigma machine would work. It doesn't allow for a lot of tweaking.

To launch the GUI, open a terminal inside the gui directory and run the enigma_run.py python file using

python3 enigma_run.py

Then open a browser, ideally on a laptop/desktop, and head to http://localhost:5000

In the browser, once you've set the rotors(buttons on the bottom right) and their configurations, you can begin typing letters on your keyboard.

You should be able to see encrypted letters light up on the screen.

The Enigma Class

The enigma machine class in this project is a simulator of an actual enigma machine, where you can do almost everything that can be done on an actual enigma machine.

The class allows you to set the reflector, rotors, their positions and even the ring positions and plugboard(This couldn't be done in the GUI).

To use the enigma class, start with importing the class into your script, and creating an object of the class.

from enigma import Enigma

e = Enigma(rotors='I II IV',
           reflector='B',
           rotor_positions=[3,4,10],
           ring_settings=[2,4,0],
           plugboard_connections=[('A','F'),('G','T')])

Then, encryption can be done by the encrypt() method. This method takes plaintext as argument and returns the encrypted string.

encrypted_text = e.encrypt('Plain Text')

If the reflector, rotors, rotor positions, ring settings and plugboard connections are known, passing the ciphertext to the encrypt function will return the plaintext.

Enigma Decoder

This is an enigma decoder that performs a statistically optimized bruteforce attack on the ciphertext.

Check out computerphile's video for explanation of the attack: https://www.youtube.com/watch?v=RzWB5jL5RX0

This script is based on the attack performed in that video, so thanks Computerphile!

Running the attack:

First import all functions from the decoder.py script. We'll only be using the decrypt function, but the others need to be imported because the decrypt function depends on them.

from decoder import *

Then, we decrypt:

pt, key = decrypt(ciphertext,available_rotors,plugboard_connections,max_keys,IOC)

This function returns the decrypted plaintext as well as the key. The key is a class that includes all the components that constitute an enigma key: rotors, rotor positions, ring settings, plugboard connections and the reflector.