Military Cryptanalytics, Part III

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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 [...]