Enigma Machine Emulator

A JavaScript implementation of the World War II era Enigma Machine encryption device. This emulator accurately recreates the functionality of the Enigma M3, including the plugboard, three rotors, and the reflector.

Features

• Implements the historical Enigma M3 machine components:
  • Five available rotors (I, II, III, IV, V) with their authentic wiring
  • UKW-B reflector with historical wiring
  • Plugboard supporting up to 10 plug pairs
  • Accurate stepping mechanism with rotor notches
• Supports encryption and decryption of text
• Handles spaces in input text (though the original machine had no space bar)

Installation

npm install

Running the Emulator

Run the emulator using Node.js:

node cli.js

This will process the input text defined in cli.js and output the encrypted result.

Usage

The emulator is controlled via a command-line interface. The following commands are available:

• process <message>: Encrypts the given message.
• settings: Displays the current machine settings (rotors, plugboard, etc.).
• load [filename]: Loads machine settings from a file. Defaults to ./data/machineSettings.enigma.
• save [filename]: Saves the current machine settings to a file. Defaults to user_settings/enigma_settings.enigma.
• exit, quit, bye: Exits the application.

Components

For a detailed explanation of how the Enigma machine works and the mathematical equations behind its operation, please refer to the Enigma Explanation Document.

PlugBoard

• Implements the plugboard (Steckerbrett) that allows letter pairs to be swapped
• Supports up to 10 plug pairs
• Validates input to ensure only valid letter pairs are used

Rotor

• Implements the mechanical rotors with their unique wiring configurations
• Handles rotor stepping and notch positions
• Supports ring settings and initial positions
• Processes signals in both forward and reverse directions

Reflector

• Implements the UKW-B reflector with historical wiring
• Reflects the signal back through the rotor system

API Usage

The project also includes a simple API server using Express.js that allows you to interact with the Enigma machine programmatically.

Running the API Server

To start the API server, run:

node server.js

The API will be listening on http://localhost:4000.

Endpoints

POST /process

Processes a message using the Enigma machine with the provided settings.

• Method: POST
• URL: /process
• Content-Type: application/json
• Request Body:

{
  "settings": {
    "plugboard": ["AZ", "BY"],
    "rotors": [
      { "name": "I", "ring": 0, "position": 0 },
      { "name": "II", "ring": 0, "position": 0 },
      { "name": "III", "ring": 0, "position": 0 }
    ],
    "reflector": "UKW-B"
  },
  "message": "HELLOWORLD"
}

• Response:

{
  "result": "ENCRYPTEDMESSAGE"
}

• Example (using curl):

curl -X POST -H "Content-Type: application/json" \
-d '{"settings":{"plugboard":["AZ","BY"],"rotors":[{"name":"I","ring":0,"position":0},{"name":"II","ring":0,"position":0},{"name":"III","ring":0,"position":0}],"reflector":"UKW-B"},"message":"HELLOWORLD"}' \
http://localhost:4000/process

Testing

The project includes comprehensive tests using Jest. Run the tests with:

npm test

Historical Note

The Enigma Machine was a cipher device used by Nazi Germany during World War II. This implementation is based on the Enigma M3, which was widely used by the German military services and was one of the most common variants.

License

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

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.