Nomenclators:
One once-common variant of the substitution cipher is the nomenclator. Named after the public official who announced the titles of visiting dignitaries, this cipher uses a small code sheet containing letter, syllable and word substitution tables, sometimes homophonic, that typically converted symbols into numbers. Originally the code portion was restricted to the names of important people, hence the name of the cipher; in later years, it covered many common words and place names as well. The symbols for whole words (codewords in modern parlance) and letters (cipher in modern parlance) were not distinguished in the ciphertext. The Rossignols‘ Great Cipher used by Louis XIV of France was one. [Wikipedia]
Not quite a match for my example, though, which is in “How scientists are cracking historical codes to reveal lost secrets,” Joshua Howgego, NewScientist (23 September 2023, paywall):
But unless your cipher is very basic, it won’t stop there. Many historical ciphers also contain elements called nomenclators, symbols that represent syllables, whole common words or names. These can be extremely hard to crack unless you have some sense of what the letter is about or who wrote it and can make an educated guess about what the nomenclators mean. Sometimes, these symbols can even be “nulls” – characters that have no meaning and should be discounted – just to throw adversaries off the scent.
Perhaps an example of language changing over time? In any case, a fascinating intro article on the automation of encryption breaking. No mention of everyone’s favorite encrypted, or so at least some speculate, manuscript, the Voynich Manuscript.
