Puzzling

On 4th June this year, Chester Nez (93) died . He was the last of the Navaho code talkers. In all the reading I've done on cryptography, codes, and ciphers, the story of the American Indian code talkers is my favourite. Before we delve into their fascinating story, I need to be explain the difference between a code and a cipher. Codes A code is a mapping of a word, a short phrase, or even a whole sentence, to a single collection of symbols (words, numbers, or other symbols). They are almost impossible to break through analysis. However, unless it's a very brief code (which can be memorised), a code requires a codebook. There is simply no way to remember all of the substitutions accurately (unless you have a photographic memory!). The existence of this codebook is a security hazard, though. If the enemy gets a copy, you've had it. Some examples of codes are: @! = the contract has been signed pancake = come at once, bring syrup 169 = the plan is proceeding ...