And Variations

Format: # of rotors:

Rotor initialization:

Plugboard initialization:

Input

Plugboard in

Forward signal

Wheel indicator

Notch sensor

Reflected signal

Plugboard out

Output

A reimagined enhanced emulation of the notorious Enigma electromechanical stepping rotor stream ciphering machine used by the Third Reich during World War II. 
It is based upon a symmetric key polyalphabetic substitution cipher where one or more of the substitution vectors varies deterministically with each plaintext character that is enciphered/deciphered.  
This version allows for the user-settable plugboard, wheel starting positions and ring offsets fundamental to the design as well as choice of 6 different modular alphabets and arbitrary rotor number/choices.
The stator (ETW) here is realized as an additional nonstepping rotor.  The reflector has a settable starting position, which is apparently a feature in some models.   
All emulations are realizable in a purely electromechanical machine of similar design to the original without a need for logic circuitry.
This emulation includes some of the flaws of the original, such as prohibition of self-encipherment, long stepping periods of downstream rotors,
pairing of contacts on plugboard, pairwise wiring of reflector and (potentially) decreased substitution period after a rotor whose number of notches is not coprime to the number of contacts.  
Probably highly vulnerable to modern cryptanalysis.