History & CultureHow it works
How Enigma encrypted, and which part gave it away.
With every keypress, current flowed through a plugboard, three rotating rotors and a reflector, then back, lighting up a letter. Because a rotor advanced after each character, the same letter was encrypted differently each time. But the reflector had a consequence: no letter could ever appear as itself. Codebreakers used exactly that to rule out possibilities.
Useful: A system is only as secure as its most convenient simplification.
Source: en.wikipedia.org