Military Cryptanalytics

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Military Cryptanalytics (or MILCRYP as it is sometimes known) is a revision by Lambros D. Callimahos of the series of books written by William F. Friedman under the title Military Cryptanalysis. It also contains contributions by other cryptanalysts. It was a training manual for National Security Agency and military cryptanalysts. It was published between 1957 and 1977, though parts I and II were written in 1956 and 1959.

From the Introduction in Part I, Volume I, by Callimahos: "This text represents an extensive expansion and revision, both in scope and content, of the earlier work entitled 'Military Cryptanalysis, Part I' by William F. Friedman. This expansion and revision was necessitated by the considerable advancement made in the art since the publication of the previous text."

The series consists of several parts, the first two of which have been declassified; the third has so far only been released in such a severely redacted form that it wasn't considered worth publishing on its own. (The unredacted portions repeat material from the first two parts.)

Callimahos referred to parts III-VI at the end of the first volume: "...Part III will deal with varieties of aperiodic substitution systems, elementary cipher devices and cryptomechanisms, and will embrace a detailed treatment of cryptomathematics and diagnostic tests in cryptanalysis; Part IV will treat transposition and fractioning systems, and combined substitution-transposition systems; Part V will treat the reconstruction of codes, and the solution of enciphered code systems, and Part VI will treat the solution of representative machine cipher systems."

Parts IV through VI were contemplated by Lambros D. Callimahos, but not completed before his death.

Both Military Cryptanalytics and Military Cryptanalysis have been subjects of FOIA requests, including one by John Gilmore.

Parts I and II are available from Aegean Park Press. Each part consists of two volumes: the first volume contains the tutorial text and the second volume contains appendices. Part I includes material on both uniliteral and multiliteral ciphers and polyalphabetic ciphers. Part II includes material on repeating-key and bipartite systems and periodic ciphers. Part II, volume II includes the Zendian Problem, a practical exercise in traffic analysis and cryptanalysis.

For the Aegean Park Press edition, Wayne G. Barker added programs for the TRS-80.