Considering different groundsettings for these messages:



HIU HKQ (where similar letters were known as (1,4) ,(2,5) females etc.

I think the cipher clerk rotated the rotors based on the groundsettings with an offset of the 3 for the 2nd enigma in a pair. While that might produce the same letter in each enigma in a pair whether Bomba gives an accurate result of rotor order and ring settings. In other words can bomba still halt but give you different settings other than the one Germans used.


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Not sure I follow your question and example. For a start, the Bombe did not look for the correct key settings, it excluded impossible/wrong key settings. Since it exclude wrong setting then when it stops it might be a good stop or a false stop. They did calculate the number of stops they expected in a complete run (don't remember exact but <10) and later that calculation prove to be correct.

The groundsettings you show seems to be related to the repeated key that was used in the beginning. For that they used Zygalski/Jeffrey sheets to find wheels and key settings, that has nothing to do with the Bombe.

  • $\begingroup$ Well I have read in the book 'Decrypted Secrets' by 'F.L Bauer'(p.379) that Rejewski used a polish bomba to figure out the Enigma settings. Am I right? $\endgroup$
    – justin
    Nov 15, 2017 at 0:13

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