Most people acquainted with cryptology, either through sensational cloak-and-dagger stories or through newspaper cryptograms, are not aware that many aspects of this art may be treated systematically, by means of some fundamental mathematical concepts and methods.

In this book, Sinkov gives us the mathematical side of elementary cryptography, the single and multiple replacement functions, transpositions, and the like used to encode messages, and how to crack such ciphers. He also shows how the code breaker uses statistical and other regularities of language to deduce the coding and decoding functions.

Also included are BASIC programs developed by Paul L. Irwin for use in his course based on this book.