HOW THE ENIGMA MACHINE WORKS
An electro-mechanical polyalphabetic substitution cipher machine developed in the early 20th century to encrypt and decrypt classified military telecommunications.
HISTORICAL CRYPTOGRAPHY ARCHIVE: The mechanical key space of the Enigma relies on complex rotor stepped permutation combined with plugboard character swapping and symmetric reflection.
Core Electro-Mechanical Components
- Plugboard (Steckerbrett): Located at the front of the unit, swapping up to 10 pairs of letters before electrical signals enter the rotor assembly.
- Rotor Drum (Walzen): A series of rotating wheels that continuously shift internal wiring configurations after each keystroke, creating a moving polyalphabetic cipher.
- Reflector (Umkehrwalze): Sends the electrical current back through the rotor stack in reverse order, ensuring reciprocal operation (encrypting and decrypting with the same settings).
- Lampboard: Displays the illuminated output character corresponding to the depressed key on the keyboard.
Cryptographic Vulnerabilities
Despite its vast state space, structural design constraints—most notably that a letter could never encrypt to itself—provided Polish and British cryptanalysts (such as Marian Rejewski and Alan Turing) the mathematical leverage needed to break the code mechanically using the Bombe.