I am writing a python program for the Enigma machine. I know what the ground setting (Grundstellung) is but I don't know the difference between ground setting and ring setting.

  • What's different between ground setting and ring set in the Enigma machine?

1 Answer 1



As stated on Wikipedia:

  • Ring settings (Ringstellung) – the position of each alphabet ring relative to its rotor wiring.
  • Starting position of the rotors (Grundstellung) – chosen by the operator, should be different for each message.


The ring setting changes the output letter of a rotor. A rotor has a fixed permutation installed (by the wiring) as seen here, i.e. one rotor would encrypt the letter A to the letter G. After one encryption the rotor would turn and the next wiring comes into effect and the new encryption of the letter A would now be encrypted to the letter C.

With the ring setting you could additionally change this fixed permutation of the rotor, i.e. with a ring setting of B (a.k.a. 02) it would change the output of the rotor. It functions like a caesar cipher. Using the example above with the ring setting of B would change the letter A to the letter H (because B is mapped to A (difference of 1) H is mapped to G).

  • $\begingroup$ but wires in a rotor are fix so why we have different output with one input? $\endgroup$ Commented Oct 31, 2019 at 18:50
  • $\begingroup$ @RamtinMoradi The turnover notch is attached to the ring, not the inner rotor. So the only functional difference (aside from changing the displayed letter) is that you are changing the location in the sequence where the next rotor turns over. $\endgroup$
    – captncraig
    Commented Dec 3, 2019 at 3:09

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