"keynumber" - 1 õppematerjal

TheCodeBreakers

some are compiled for private firms, many others are sold to the public and therefore provide no real secrecy. Most ciphers employ a key, which specifies such things as the arrangement of letters within a cipher alphabet, or the pattern of shuffling in a transposition, or the settings on a cipher machine. If a word or phrase or number serves as the key, it is naturally called the keyword or keyphrase or keynumber. Keys exist within a general system and control that system's variable elements. For example, if a polyalphabetic cipher provides 26 cipher alphabets, a keyword might define the half dozen or so that are to be used in a particular message. Codewords or codenumbers can be subjected to transposition or substitution just like any other group of letters or numbers—the transforming processes do not ask that the texts given to them be intelligible.