Part 5/17:
Understanding Enigma’s architecture reveals why it was initially considered unbreakable. Each press of a key ran an electrical current through wired rotors, changing the substitution cipher with every keystroke via stepwise rotation. Additional security was provided by the plugboard, where pairs of letters could be swapped, and the reflector, which prevented a letter from encrypted to itself—a feature that later proved crucial.
The Germans relied heavily on procedural keys shared daily, believing that changing rotor positions, plugboard settings, and initial configurations kept their cipher secure. They also considered their procedures, manuals, and training as vital layers of defense, believing that secrecy of design, combined with procedural discipline, created an impregnable system.