How does the Enigma machine rotor mechanism work?

The Enigma machine uses an electromechanical rotor mechanism that scrambles the 26 letters of the Latin alphabet as text is entered. With each keypress, the rotors step and change the electrical connections between the keyboard and the illuminated indicator lights. This motion ensures that every letter is encrypted with a different cryptographic key, making the ciphertext highly resistant to conventional frequency analysis.

What we know

• The Enigma machine features an electromechanical rotor mechanism that scrambles the 26 letters of the Latin alphabet. [2, 3]
• The rotor mechanism changes the electrical connections between the keys and the indicator lights with each keypress. [2]
• Because the rotor moves continuously, every typed letter is encrypted using a different cryptographic key. [2]
• Entering ciphertext into the machine transforms it back into readable plaintext, provided the exact operational settings are used. [2]

Where to go next

• how we knowHow did Marian Rejewski break the Enigma cipher?
• whoWhat was the role of Alan Turing in cracking Enigma?
• the bigger pictureWhat is a rotor machine in cryptography?
• how it workedHow did the British Bombe reverse-engineer Enigma settings?
• compared withHow did the Kriegsmarine four-rotor Enigma differ from standard models?
• an unexpected connectionHow did French espionage assist early codebreaking?Polish cryptanalysis succeeded partly because French intelligence supplied material obtained from a German spy inside the Reich.

Sources

• [1]Enigma (Wikidata Q150758) · CC0 1.0
• [2]Enigma machine · CC BY-SA 4.0
• [3]Rotor machine · CC BY-SA 4.0
• [4]Cryptanalysis of the Enigma · CC BY-SA 4.0
• [5]Bombe · CC BY-SA 4.0