You never know....this is slightly OT, but I was reading on the history of The Culper Spy Ring. They had a dictionary of sorts of about 700+ numbers that when represented different words, etc. They have the key on the Mt. Vernon website. It was quite complicated - it's not like they had excel spreadsheets. Now think of all the nonsense tweets we see where it is too obvious messages are being sent - we just don't have the decoder ring.

https://www.mountvernon.org/george-washington/the-revolutionary-war/spying-and-espionage/the-culper-code-book/