Enigma Machine Simulator

Authentic WWII Enigma M3 — Rotors I–V, Reflectors B/C, plugboard, double-step anomaly.

Current Rotor Positions
A
A
A

Enigma Settings

Plaintext
Ciphertext
Rotor: I-II-III — Reflector: B — 0 plugboard pairs

How to Use the Enigma Simulator

  1. Configure settings — click Settings to choose rotors, starting positions, ring settings, and plugboard pairs.
  2. Apply settings — click Apply to lock in your configuration. The rotor windows update to show starting positions.
  3. Type your message — enter text in the Plaintext box. The machine encrypts as you type.
  4. Copy the ciphertext — use the Copy button to copy the encrypted message.
  5. Decrypt — reset to the same starting positions and type the ciphertext to recover the original message.

About the Enigma Machine

The Enigma machine was the primary encryption system used by Nazi Germany during World War II. It was an electromechanical device that combined rotating wheels (rotors), a plugboard (Steckerbrett), and a reflector to produce a polyalphabetic substitution cipher. The Wehrmacht, Luftwaffe, and Kriegsmarine all used Enigma, with the naval variant adding a fourth rotor to create the more complex Enigma M4.

How Enigma Works

When an operator pressed a key, an electrical signal passed through the plugboard, then through three rotors right-to-left, was reflected by the reflector, passed back through the rotors left-to-right, and lit up a lamp on the lampboard. After each keypress, the rightmost rotor advanced one step — like an odometer. When the rightmost rotor completed a full revolution, it advanced the middle rotor (via the notch mechanism). The notorious double-step anomaly means the middle rotor sometimes advances two steps in a row: once when it carries to the left rotor, and once on the next step when the right rotor is still at the notch position.

Ring Settings and Starting Positions

Each rotor has a ring setting (Ringstellung) that offsets the internal wiring relative to the alphabet ring on the rotor's exterior. Starting positions are the visible letters in the rotor windows when the message key is set. In wartime practice, operators used a codebook for daily settings (rotor order, ring settings, plugboard pairs) and then transmitted an encrypted message key at the start of each message to set the starting positions for the actual message.

Why Enigma Was Broken

Cryptanalysts at Bletchley Park, led by Alan Turing and Gordon Welchman, exploited several weaknesses: Enigma never encrypted a letter to itself; message keys were initially transmitted twice (later abandoned); operators often used predictable cribs (known plaintext) like weather reports starting with "WETTER"; and the reflector made the cipher reciprocal. Turing's Bombe machine used these properties to rapidly eliminate impossible rotor settings, eventually cracking the daily keys. The intelligence produced, known as Ultra, is credited with shortening the war by up to two years.

Frequently Asked Questions

The Enigma machine was an electromechanical cipher device used by Nazi Germany during WWII. It scrambled messages using rotating wheels (rotors), a plugboard, and a reflector, creating an extremely large keyspace that was eventually broken by Allied codebreakers at Bletchley Park.
The reflector ensures the signal path is always symmetric. A letter can never encrypt to itself, which made the machine self-deciphering but was also a cryptographic weakness that Bletchley Park exploited.
When the middle rotor is at its notch position, it advances both itself and the left rotor in the same step, meaning the middle rotor sometimes takes two consecutive steps in a row. This is an anomaly compared to a normal odometer mechanism.
The plugboard connects pairs of letters with cables, swapping them before and after the rotors. If A-Z are connected, pressing A sends Z into the rotors. Up to 13 pairs can be used, though typically 6–10 were used in wartime settings.
Yes. This simulator uses the exact wiring tables for Rotors I–V and Reflectors B and C from historical documentation, with the double-step anomaly faithfully implemented. Messages encrypted here can be decrypted by other accurate Enigma simulators using identical settings.