Elementary cryptanalysis

A practical instructional treatment of classical cryptanalysis that concentrates on techniques for analyzing and solving encrypted messages rather than codes or chemical and mechanical devices. It surveys concealment methods, transposition and geometrical systems, irregular and columnar types, single- and polyalphabetic substitution (including Vigenère, Gronsfeld, Beaufort, and Playfair), periodic-cipher analysis such as the Kasiski method, auto-encipherment, and approaches for attacking unknown ciphers. Each topic is presented with explanatory discussion, worked examples, and practice cryptograms, while appendices provide frequency tables, digram/trigram data, common-word lists, charts, and a bibliography to support statistical and linguistic decryptment methods.