CODES, CIPHERS AND SECRET WRITING

Drawing extensively (and with due acknowledgement) on Kahn's exhaustive 1,164-page Code-breakers (1967) and on Gardner's own considerable expertise in the field of mathematical games and puzzles, this is a stimulating must for the intermediate cryptographer who has outgrown Zim's model introduction and wants more nitty-gritty brainwork than Laffin's historical treatment provides. Gardner covers easy transposition and substitution ciphers and harder polyalphabetic ones, as well as grilles (grids), various kinds of invisible writing and ""bizarre methods"" of sending codes, with examples, anecdotes, a little theory, and instructions on breaking and composing ciphers. He explains even the more difficult examples with admirable clarity, alludes to literature (frequently), history, math and science (including the genetic code) with fingertip control, ends with a discussion of radio codes prepared for interplanetary communication, and appends an excellent annotated bibliography.