Military Cryptanalytics, Part III

Post Syndicated from Bruce Schneier original

The NSA has just declassified and released a redacted version of Military Cryptanalytics, Part III, by Lambros D. Callimahos, October 1977.

Parts I and II, by Lambros D. Callimahos and William F. Friedman, were released decades ago — I believe repeatedly, in increasingly unredacted form — and published by the late Wayne Griswold Barker’s Agean Park Press. I own them in hardcover.

Like Parts I and II, Part III is primarily concerned with pre-computer ciphers. At this point, the document only has historical interest. If there is any lesson for today, it’s that modern cryptanalysis is possible primarily because people make mistakes

The monograph took a while to become public. The cover page says that the initial FOIA request was made in July 2012: eight and a half years ago.

And there’s more books to come. Page 1 starts off:

This text constitutes the third of six basic texts on the science of cryptanalytics. The first two texts together have covered most of the necessary fundamentals of cryptanalytics; this and the remaining three texts will be devoted to more specialized and more advanced aspects of the science.

Presumably, volumes IV, V, and VI are still hidden inside the classified libraries of the NSA.

And from page ii:

Chapters IV-XI are revisions of seven of my monographs in the NSA Technical Literature Series, viz: Monograph No. 19, “The Cryptanalysis of Ciphertext and Plaintext Autokey Systems”; Monograph No. 20, “The Analysis of Systems Employing Long or Continuous Keys”; Monograph No. 21, “The Analysis of Cylindrical Cipher Devices and Strip Cipher Systems”; Monograph No. 22, “The Analysis of Systems Employing Geared Disk Cryptomechanisms”; Monograph No.23, “Fundamentals of Key Analysis”; Monograph No. 15, “An Introduction to Teleprinter Key Analysis”; and Monograph No. 18, “Ars Conjectandi: The Fundamentals of Cryptodiagnosis.”

This points to a whole series of still-classified monographs whose titles we do not even know.

EDITED TO ADD: I have been informed by a reliable source that Parts 4 through 6 were never completed. There may be fragments and notes, but no finished works.