Treatise on Cryptography

Treatise on Cryptography is Aegean Park Press's English edition of André Lange and E.-A. Soudart's Traité de Cryptographie, first published in Paris by Librairie Félix Alcan in 1925.

The original French text opens with five chapters tracing the history of cryptography from antiquity to the early twentieth century. It then turns to technical treatment of transposition methods, substitution methods, codes, cryptographic devices, and cipher machines, illustrated with roughly 100 tables and drawings across 366 pages. The Aegean Park edition presents this material in English, not in facsimile French. A Google Books record for the English edition credits the US Office of the Chief of Naval Operations as a contributor. That points to Aegean Park having reprinted an existing US Navy translation of the work, rather than commissioning a new one.

Lange and Soudart's treatise is counted among the standard general studies of cryptography from the interwar period. It sits alongside works such as Givierge's Cours de Cryptographie and Figl's Systeme des Chiffrierens. Together, these shaped cryptology before the rise of machine cryptanalysis.