Hello, German friends,

I am interested in finding out more about a German cipher used during WW I, but I don't live in Germany and don't read German very well. Americans called the cipher "Fuer GOD" because messages always began with FUERGOD (GOD was the call sign of the receiver) or "Wilhelm" (for no good reason). I do not know the true name of the cipher. It was a periodic polyalphabetic substitution with a nonstandard tableau of substitutions. These papers contain everything that I know so far; none of them are by Germans:

J. Rives Childs; German Military Ciphers from February to November, 1918; 1918; https://www.nsa.gov/Portals/75/documents/news-features/declassified-documents/friedman-documents/publications/FOLDER_268/41784789082381.pdf

Greg Mellen, “Cryptanalyst’s Corner,” Cryptologia 8:1 (1984) 55-57, DOI: 10.1080/0161-118491858773

Hans van der Meer, An old challenge, 2010, https://staff.fnwi.uva.nl/h.vandermeer/pubs/fuergod.pdf

There are also some unpublished papers by Childs at University of Virginia; I am making inquiries into seeing those.

The tableau is missing rows J, Q, X, Y, but that is not a problem if the table was created without them; none of the keys in use required them. A bigger problem is that there are duplicated letters in some of the existing rows in the tableaux given in these papers, and this makes for a bad cipher.

My question is this: Are you able to find any information that the German government may have about it or any true ciphertexts used in the past? From enough ciphertexts I can resolve the problems with the tableau.

Thank you in advance. I am willing to repay your efforts by designing a challenge with this cipher if we can completely determine the tableau.