ENIGMA M3

1. Rotor Selection

Select three different rotors for the Left, Middle and Right positions. Rotor order matters: I–II–III is different from III–II–I. Use the ▲ and ▼ controls to set the letters visible in the three rotor windows. These are the starting positions. The rotors advance automatically with each keypress, including the historical middle-rotor double-step.

2. Ring Settings (Ringstellung)

The three ring settings adjust the alphabet ring relative to each rotor's internal wiring. A–A–A is the default. Ring settings are separate from the letters shown in the rotor windows. Set the rings first, then set the desired starting rotor positions.

3. Reflector (UKW)

Select reflector B or C. The reflector returns the electrical signal back through the rotors. Encryption and decryption must use the same reflector.

4. Plugboard (Steckerbrett)

Enter letter pairs separated by spaces, for example: AV BS CG DL FU HZ IN KM OW RX. Each pair swaps those two letters before the signal enters the rotors and again after it returns. A letter should be used in only one pair. Leave the field blank to operate without plugboard connections.

5. Signal Path

6. Encrypting

Choose the rotor order, ring settings, reflector, plugboard pairs and starting rotor positions. Type A–Z on the computer keyboard or click the machine keys. Each keypress advances the rotor mechanism and illuminates the encrypted letter. The INPUT and OUTPUT boxes keep a record of the message.

7. Decrypting

There is no separate decrypt switch. Return the machine to exactly the same initial settings used by the sender and type the ciphertext. The output will reproduce the original plaintext. Rotor order, ring settings, reflector, plugboard and initial rotor positions must all match.

Example Key

Rotors: II IV V   |   Rings: B L A   |   Reflector: B
Start: W X C   |   Plugboard: AV BS CG DL FU HZ IN KM OW RX

Buttons

CLEAR TEXT erases the displayed message without changing the current rotor positions. RESET A-A-A clears the message and returns all rotor windows to A. COPY OUTPUT copies the output to the clipboard.