Enigma Machine Simulator
A working Enigma I, the cipher machine of the German military in World War II. Choose three of the five historical rotors and a reflector, set the ring settings and start positions, wire up the plugboard, then type: lamps light, rotors step (including the famous double-step anomaly), and a live wiring diagram traces your letter’s full path — through the plugboard, three rotors, the reflector and all the way back. Encrypt and decrypt whole messages with authentic behaviour, follow the odometer-style rotor windows, and see with your own eyes the machine’s fatal flaw: no letter can ever encrypt to itself — the crack Bletchley Park drove a bomb through.
Runs 100% in your browser — simulations are computed locally on your device.
Read the full guide to this tool
Notes
- Rotor wirings, notch positions and reflectors are the historical ones (rotors I–V, reflectors B and C), so settings from real procedure books and museum machines reproduce exactly.
- The double step: whenever the middle rotor is at its notch it steps together with the left rotor — a mechanical quirk of the pawl mechanism that shortens the machine’s period and helped cryptanalysts.
- Because the reflector sends every signal back through the rotors, encryption is self-inverse — the same settings decrypt — and no letter maps to itself, a regularity that made "cribs" possible and doomed the cipher.
- The plugboard contributed most of the key space (over 150 trillion combinations with 10 cables), yet the Bombe sidestepped it almost entirely — key size is not security.
- Runs 100% in your browser — keys and data never leave your device.
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