Stage three
Enigma Training
Inside the machine. Trace the current through plugboard, rotors and reflector, then learn the guaranteed flaw that let Bletchley in.
The machine
Free practice. Set the rotors, type a message, then return the rotors to the same start position and type the cypher back to decrypt it.
Machine settings
Electrical path
Press a key below and watch the current travel across the schematic: keyboard, plugboard, static wheel, three scrambler cogs, reflector, back through the cogs, plugboard again, then the lamp.
Lampboard
Keyboard
Message tape
In: —
Out: —
Type the output back into a machine with the same starting settings and the original message comes out. That is why Enigma needed no separate decoding machine.
Why no letter can encrypt to itself
Nowhere in that list does a letter map to itself. The reflector always pairs a letter with a different letter, and the return journey can never undo that. This single weakness is what made cribs — guessed plaintext — so powerful.
Whole message (start position AAA)
KLHFRTDYCUFON