Py-Enigma is a Python 3 library for simulating the Enigma machines used by the German armed forces (Wehrmacht) during World War 2. Py-Enigma makes it possible to both encrypt and decrypt messages that can be sent to, or received from, actual Enigma machines used by the German army (Heer), air force (Luftwaffe), and navy (Kriegsmarine).

It is my hope that library will be useful to Enigma enthusiasts, historians, and students interested in cryptography.

Py-Enigma strives to be Pythonic, easy to use, comes with unit tests, and documentation.

The current scope of Py-Enigma is to simulate Wehrmacht Enigma machines. Simulation of other Enigmas, such as the various commercial, railroad, foreign, and Abwher (Military Intelligence) models may come later if there is enough interest and data available.

Currently, Py-Enigma can simulate the 3 and 4 rotor Enigma machines used by the German army, navy, and air force.

This example shows how the library can be used to decode a message using the procedure employed by the German army:

from enigma.machine import EnigmaMachine

# setup machine according to specs from a daily key sheet:

machine = EnigmaMachine.from_key_sheet(
       rotors='II IV V',
       reflector='B',
       ring_settings=[1, 20, 11],
       plugboard_settings='AV BS CG DL FU HZ IN KM OW RX')

# set machine initial starting position
machine.set_display('WXC')

# decrypt the message key
msg_key = machine.process_text('KCH')

# decrypt the cipher text with the unencrypted message key
machine.set_display(msg_key)

ciphertext = 'NIBLFMYMLLUFWCASCSSNVHAZ'
plaintext = machine.process_text(ciphertext)

print(plaintext)

This program prints:

THEXRUSSIANSXAREXCOMINGX

Py-Enigma also includes a command-line application for processing messages. Assuming you have a proper key file that contains the same initial settings as the code above, the above example can be performed on the command-line:

$ pyenigma.py --key-file=keys.txt --start=WXC --text='KCH'
BLA
$ pyenigma.py --key-file=keys.txt --start=BLA --text='NIBLFMYMLLUFWCASCSSNVHAZ'
THEXRUSSIANSXAREXCOMINGX

The format of the key file can be found in the documentation.

Py-Enigma is written in Python, specifically Python 3.2. It has no other requirements or dependencies.

Py-Enigma is available on the Python Package Index (PyPI). You can install it using pip:

$ pip install py-enigma             # install
$ pip install --upgrade py-enigma   # upgrade

You may also download a tarball or .zip file of the latest code using the "get source" link on the Py-Enigma Bitbucket page. Alternatively if you use Mercurial, you can clone the repository with the following command:

$ hg clone https://bitbucket.org/bgneal/enigma

If you did not use pip, you can install with this command:

$ python setup.py install

The latest documentation is available at Read the Docs. There you can browse the documentation online, or download it in a variety of formats.

Sources for the documentation are also included in Sphinx format. If you install Sphinx you can generate the documentation in several output formats.

Support is provided at the issue tracker at the Py-Enigma Bitbucket page. If you have general questions or comments, please feel free to email me (address at the top of this file).

And please, if you use Py-Enigma for anything, even if it is just learning, please let me know!

This software would not have been possible without the thorough and detailed descriptions of the Enigma machine on Dirk Rijmenants' incredible Cipher Machines and Cryptology website. In particular, his Technical Details of the Enigma Machine page was a gold mine of information.

Dirk has also written an Enigma simulator in Visual Basic. Although I did not look at his source code, I did use his simulator to check the operation of Py-Enigma.

I would also like to recommend the photos and video at Dr. Thomas B. Perera's Enigma Museum.

Another good website is The Enigma and the Bombe by Graham Ellsbury.

A nice video which shows the basic components and operation of the Enigma Machine is on YouTube: Nadia Baker & Enigma demo.