Pynigma

A modern implementation of the Enigma machine in Python.

Background

In the past month I have finally managed to see The Imitation Game, the famous 2014 movie (yep, it took me a long while) about Alan Turing and its incredible breaking of the german crypto machine Enigma.

Since I was a kid, I have been really fascinated by this machine. I couldn't understand how it worked, let alone how it was cracked without any kind of computer.

An electromechanical machine that was so secure that took years to be decrypted! That can't be true!

So, in order to understand a little bit more how this marvelous machine worked, I decided to try and implement by using the best programming language ever and ever in the past, present and future or computers (Python3).

For the first time I actually started using common sense and modern coding recommendations:

1. Type hinting
2. A meaningful and complete testing suite

I have to say, I don't regret this the least. Making a proper set of tests really helped me a lot.

Who could have ever imagined that? Well.

At this point, there's almost more test than code. Isn't this how it should work?

How to use

The class EnigmaFactory creates Enigma machines based off real models, produced before and during WWII, while the class CustomEnigmaFactory allows you to create, well, Enigma machines with custom settings (rotors, plugboards and deflectors).

Code reference

Code snippets

Create a machine using the EnigmaFactory class

f = EnigmaFactory()
print(f.models) # list all available models
for m in f.models:
  e = f.createEnigma(m)
  print(e) # get some infos about the machine

Create a custom machine using the CustomEnigmaFactory class

# TODO

Compose an Enigma machine using the default Enigma class

By using the Enigma class, a *quasi-*replica of the 1938 model M3.

# TODO

Encrypt and decrypt a message

from Enigmafactory import EnigmaFactory

f = EnigmaFactory()
e = f.createEnigma("M3")

# list reflectors, rotors
print(e.availableRotors, e.available_UKWs, e.available_ETWs)
# setup rotors and reflectors
e.setRotors(["I", "III", "II"])
e.setUKW("UKW-B")
e.setETW("ETW")
# set rotors position
e.setRotorsPositions("AZE")
# set a plugboard (max 10)
e.setPlugboard(["AB", "DE", "KC", "QW"])

# now encode
print(e.encode("HELLO WORlD"))

# reset rotors positions
e.setRotorsPositions("AZE")

# now decode
print(e.decode("")) # TODO

Credits

Thanks to Crypto Museum for the rotors wiring and all the information about various models. It's a really interesting website that you should check out!

Licensing

This project is distributed under Attribution 4.0 International (CC BY 4.0) license.