Enigma Machine (Domain)

This repository contains a .NET 8 domain library that models the WWII Enigma machine. It follows DDD/Clean Architecture principles: the domain is infrastructure-free and test-driven.

Projects

• EnigmaMachine.Domain: core business logic (rotors, plugboard, reflector, machine, factories, value objects)
• EnigmaMachine.Domain.Tests: xUnit tests covering encoding scenarios and stepping

Build and test

# from repo root
 dotnet restore
 dotnet build -c Release
 dotnet test -c Release --nologo -v minimal

Scope

• Enigma I (3 rotors) with Reflector B
• Historical rotor wirings I–V and correct double-stepping behavior
• UI-friendly diagnostics via IDiagnosticEnigmaMachine (see Domain README)

Notes

• Non-thread-safe: create separate instances per concurrent operation
• Inputs are normalized to uppercase A–Z

See EnigmaMachine.Domain/README.md for domain details.

Example (left-to-right overload)

using EnigmaMachine.Domain.Entities;
using EnigmaMachine.Domain.Factories;
using EnigmaMachine.Domain.Interfaces;
using EnigmaMachine.Domain.ValueObjects;

var plugboard = new Plugboard();
foreach (var pair in new[] { "BA", "QU", "CG" })
	plugboard.Connect(new PlugboardPair(pair[0], pair[1]));

var reflector = new ReflectorB();

// Supply left-to-right (slow to fast) order; API reverses to machine order internally
var machine = EnigmaMachineFactory.CreateEnigmaILeftToRight(
	new[] { RotorType.I, RotorType.III, RotorType.V },
	new[] { 'A', 'B', 'C' },          // ring settings L→R
	new[] { 'X', 'Y', 'Z' },          // initial positions L→R
	plugboard,
	reflector);

// Process text
var input = "HELLO WORLD";
var sb = new System.Text.StringBuilder();
foreach (var ch in input)
{
	if (!char.IsLetter(ch)) { sb.Append(ch); continue; }
	var letter = new Letter(ch);
	sb.Append(machine.ProcessLetter(letter).Character);
}
var cipher = sb.ToString();

// Diagnostics (optional): cast to IDiagnosticEnigmaMachine to inspect rotor positions
var diag = (IDiagnosticEnigmaMachine)machine;
// 0–25 indices, rightmost (fast) at index 0
var numeric = diag.RotorPositions;
// Rich view for UI: A–Z letters and normalized indices
var view = diag.RotorPositionsView; // RotorPosition value objects

Notes:

• The EnigmaMachine constructor validates the rotor list: it must be non-null, non-empty, and contain no null entries.