Enigma Machine Simulator

Encrypt & decrypt messages exactly like it was done in 1940

UKW B
Lampboardshows the encrypted letter
Keyboardclick a key or type on your own keyboard
Plugboard (Steckerbrett) Click two letters to connect them with a cable · click a plugged letter to remove its cable

Tape — what you typed on the machine

IN
OUT

Signal path — how the last key became its lamp

  1. Press any key to watch the electrical current travel through the machine.

Load a key

Paste a key that someone shared with you (from their Copy key button):

How to use the Enigma simulator

1

Agree on a key

Both people choose the same Machine settings: rotors, ring settings, start positions, reflector and plugboard. Use 🎲 Random key, then 📋 Copy key and send it to your friend.

2

Encrypt

Pick the 🔒 Encrypt tab, type your message and press Encrypt message. Copy the scrambled result and send it.

3

Decrypt

Your friend loads the same key (📥 Load key), picks 🔓 Decrypt, pastes the ciphertext and presses Decrypt message. The original text appears!

Two ways to use it

Why decrypting works

Enigma is reciprocal: if A becomes Q at some position, then Q becomes A at the same position. So decrypting is just encrypting the ciphertext again from the same start position. The simulator always starts a message from the start position set in Machine settings, so you never have to reset by hand.

Parts of the machine

Rotors (Walzen)
Three wired wheels that scramble the alphabet. The right rotor steps on every key press; it pushes the middle one forward once per turn, which in turn pushes the left one. Turn them by hand with the ▲ ▼ buttons, the mouse wheel or arrow keys.
Ring setting (Ringstellung)
Shifts each rotor's internal wiring relative to its letters — another part of the secret key.
Reflector (Umkehrwalze, UKW)
Sends the current back through the rotors by a different route. This is why a letter can never encrypt to itself — the flaw that helped Alan Turing and the codebreakers at Bletchley Park crack Enigma.
Plugboard (Steckerbrett)
Cables that swap pairs of letters before and after the rotors. Historically 10 cables were used, adding about 150 trillion possibilities.

Good to know