Enigma Machine Simulator
Simulate the Enigma I, M3 and M4 with rotors I–VIII, ring settings, start positions, reflectors and a plugboard, with correct double-stepping. Runs in your browser.
Enigma is symmetric: with the same settings, feeding the output back in returns the original text. A letter never encrypts to itself.
The Enigma machine enciphered German military messages in the Second World War using rotating wheels, a reflector and a plugboard. This simulator reproduces the Enigma I, M3 and M4 with the historical rotor wirings and — crucially — the "double-stepping" quirk of the stepping mechanism, so its output matches real machines.
How to use this tool
- Enter your text (letters only are enciphered).
- Choose the model, rotors, reflector, ring settings and start positions.
- Add plugboard pairs if you want (up to 13).
- Read the output; run it back through the same settings to decrypt.
Formula
Each key press first steps the rotors, then the signal passes through the plugboard, right-to-left through the rotors, the reflector, left-to-right back through the rotors and the plugboard again. Ring settings offset each rotor’s wiring.
Double-stepping: when the middle rotor is at its notch it turns on the next key press and also carries the left rotor, so the middle rotor steps twice in a row.
Example
On an Enigma I with rotors I-II-III, reflector B, rings AAA and start AAA, typing AAAAA produces BDZGO — a standard reference result. With the original settings, the simulator also reads the 1941 Operation Barbarossa message (Enigma I) and a 1942 U-boat message (M4) back to their published German plaintexts.
Frequently asked questions
Why can a letter never be itself?
The reflector sends the signal back through a different path, so the output letter is always different from the input. This was a design feature — and a weakness codebreakers exploited.
What is double-stepping?
A mechanical side effect: when the middle rotor reaches its turnover notch, it advances on the next keystroke and drags the left rotor with it, stepping twice in quick succession.
How do I decrypt a message?
Set the machine to the exact same rotors, rings, positions and plugboard used to encrypt, then type the ciphertext. Enigma is symmetric, so it returns the plaintext.
Last updated:
Page address with these inputs: https://kakao.mobile/tools/enigma-machine-simulator/
Cite or embed this tool
kakaoCalc. (2026, November 8). Enigma Machine Simulator. https://kakao.mobile/tools/enigma-machine-simulator/
“Enigma Machine Simulator.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/enigma-machine-simulator/.
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