As the culprit who started the "Native American Encryption" thread, I'd like to speak out in thanks and in favor of many answers to a question. It's true that lots of folks correctly identified Navajo as the source pf the language used. But lots of other details came in, one post at a time, that clarified the picture, and made it both more accurate and more interesting to folks interested in this fascinating chapter in the history of coding. The fact that Navajo was originally all-oral, but is now written; that the talkers used a compound of Navajo and on-the-fly slang; that real-language systems are immeasurably harder to crack than encrypted messages if you don't know they are real-life languages; etc. etc. -- I for one got a great deal out of the thread, including some references to follow up on. And all this has made me wonder if real-life languages, as opposed to algorthymic encryption schemes,.... Well, that's another thread.