enigma

The World War II's cryptic game-changer, a mechanical marvel of secrecy and encryption

This repository features a TypeScript simulation of the iconic Enigma machine — an encryption device used by the German military during World War II.

Having watched The Imitation Game movie with prior understanding of cryptography, I decided to challenge myself into creating a simulation of the basic functionality of the original Enigma machines. Then later try to break it just like Alan Turing and his collegues did.

Now the first step is done 🎉

The rest of this document tells what I found out and provides a guide to run the simulation on your computer.

To try the live demo, first check out how to use it here.

Check out the simulation in action: Try it Yourself

The Enigma machine consisted of rotors, reflector, plugboard and a keyboard. Each key press initiated a complex encryption process involving the rotation of rotors and the reflection of signals. Its daily-changing settings posed a significant challenge to Allied codebreakers.

The process of transforming an input character involves a sequence of steps through various components, including the plugboard, rotors, reflector, and plugboard again before reaching the lampboard. Here's a brief description of the transformation pipeline:

1. Plugboard:

   • The input character enters the plugboard, where initial letter swaps occur. Pairs of letters are connected, providing an additional layer of complexity to the encryption.

2. Rotors:

   • The character then passes through a series of rotors, each with its own internal wiring. As the rotors rotate with each keypress, the electrical signal is further scrambled through these intricate pathways.

3. Reflector:

   • After passing through the rotors, the signal is directed to the reflector. The reflector ensures that the signal is then sent back through the rotors in a different path, contributing to the complexity of the encryption.

4. Rotors (again):

   • The signal, now reflected, passes through the rotors again in the reverse direction. This double-pass through the rotors adds a crucial non-linearity to the encryption process.

5. Plugboard (again):

   • The signal re-enters the plugboard for a second letter swap. This final permutation provides an additional layer of complexity to the output.

6. Lampboard:

   • The transformed signal finally reaches the lampboard, where the illuminated letter represents the encrypted output. This letter corresponds to the final encrypted character.

The transformation process involves a carefully orchestrated series of steps through various components, creating a highly secure and dynamic encryption process during each keypress.

Follow these steps to set up and run the Enigma machine simulation on your local machine:

• Node.js installed on your machine

1. Clone the repository:

   git clone https://github.com/henryhale/enigma.git

2. Navigate to the project directory:

   cd enigma

3. Install dependencies:

   npm install
   # pnpm install

Run the provided example script to witness the Enigma machine in action:

• Node.js

  npm run simulate
  # pnpm simulate

• Browser

  npm run dev
  # pnpm dev

Explore the script to create your own scenarios and delve into different Enigma machine configurations.

To build the simulation for production, run the provided command

npm run build
# pnpm build

• source/: Implementation of the Enigma machine, rotors, plugboard and reflector.
• demo/simulate.ts: Example script for Node.js.
• demo/browser.ts: Example script for the browser (with index.html)

This section focuses on the browser demo taking you through how to encrypt and decrypt messages

• Open the demo locally in your browser or check out the live demo.
• Mode: Encryption - select the encrypt radio button.
• Rotors: For simplicity, leave each rotor position at 0 - A. Otherwise set the rotors to the desired positions say 0 - A, 1 - B, 2 - C. Be sure to note the order as it will be used to decrypt the messages.
• Lampboard: Everytime you input a key, the output (ciphered) key will light up.
• Input: Type the plain text message here.
• Output: The output is represented the ciphered text from the input message.
• Mode: Decryption - to decrypt the message, open the demo in another tab and select decrypt under the Mode section.
• Rotors: Set the rotor positions to the values they were at during encryption.
• Input: Enter the ciphered text into the input textarea.
• Output: The corresponding result is the plaintext you entered during the encryption.

If you have reached this point, you have got it 🎉

Contributions are welcome! If you have suggestions or improvements, feel free to open an issue or create a pull request.

• How did the Enigma work? Youtube Video
• The Imitation Game (2014) - Film
• Enigma Machine - Wikipedia article
• The Enigma Machine - Crypto Museum
• Enigma: The Battle for the Code by Hugh Sebag-Montefiore

This project is licensed under the MIT License - see the LICENSE.md file for details.

Copyright © 2023 Henry Hale