Author here, this was the last of four cryptograms from #35 of Klaus Schmeh’s list of 50 unsolved cryptograms. The first 3 were cracked in 1948, 1996 and 2019 with the last one remaining uncracked for 76 years. Wood initially set up the cipher to try to prove he could pass the key through a medium after his death.

The key ended up being the Lord's Prayer from a 1912 German Bible. The message reads Hier bin ich. Totsiens. T.E.W. "Here I am" in German, "goodbye" in Afrikaans, with Wood's initials.

Since the release of Fable I’ve been using Claude and OpenAI to try to tackle these open problems, Opus 5.5 wrote the search code and identified the books to use for the key phrase and Astra verified the results. All the code and results related to the search are up on GitHub - https://github.com/creilly11235/wood-cryptogram-1950

Klaus has confirmed the results here - https://klausschmeh.net/woods-cryptogram-from-the-crypt-anot...