Solving the 1950 cipher meant to test life after death

A Yorkshire solicitor, T. E. Wood, published a 21‑letter cipher in 1950 intended as a posthumous proof of survival, using Robert Thouless’s word‑key cipher: each message letter pairs with a distinct word from a text, the letters of that word are summed (A=1…Z=26), reduced modulo 26 to give a key letter, and that key letter defines a Caesar shift (A=0) to produce the ciphertext. Wood’s clues said he used Thouless’s method, the key is in an accessible foreign‑language book, and the message would not stay in one language. The obvious difficulty is that, without the key, many plausible plaintexts can be forced from the same 21 letters, so the search had to try consecutive word runs from many books and score multilingual plausibility rather than English alone.

The solve came when a Bible‑focused, multilingual search found the key starting at the sixth word of Matthew 6:9 in the 1912 Luther Bible (Unser Vater in dem Himmel…), using 21 distinct key words with repeated words skipped. That key decrypts to HIER BIN ICH TOTS IENS TEW, read as German “Here I am”, Afrikaans “Goodbye” and Wood’s initials T.E.W. The result was independently re‑encrypted to match Wood’s ciphertext, confirmed by experts, checked by multiple AI reviewers and code, and subjected to an extensive chance analysis that found the match to be essentially unique across hundreds of millions of trials.