History of Cryptography

The history of cryptography traces the documented development and actual use of codes and ciphers across history, from ancient substitution methods through wartime military and diplomatic codebreaking, working from primary correspondence and archival record rather than from the mathematics of cryptography considered on its own. The journalist and historian David Kahn gave the field its first comprehensive scholarly treatment with The Codebreakers, published in 1967, a history running to more than a thousand pages that traced cryptographic practice from antiquity to the mid twentieth century and established, for the first time, that the subject had a continuous documented history worth writing as history rather than only as applied mathematics.

Gematria, numerology and other cipher systems that assign hidden numerical or coded meaning to a sacred text appear across several traditions, and claims made about when such a system originated and what it was actually used for are exactly the kind of question the history of cryptography can check against the documented record of cipher practice in the same period. The atlas draws on the discipline to distinguish a documented ancient cipher tradition from a later esoteric system that borrowed the vocabulary of code and numerology for a different, later purpose.