The Enigma was an electromechanical rotor cipher machine used by Nazi Germany during WWII. This simulator models the M3 variant with 3 rotors (I-V), 2 reflectors (UKW-B/C), ring settings, and a 13-pair plugboard. Key features: each letter encrypts differently due to rotor stepping, and the machine is self-reciprocal — encrypting the ciphertext with the same settings produces the original plaintext. The Enigma was famously broken by Alan Turing and the team at Bletchley Park.