Easy Indexed Access to Declassified NSA/CSS Documents

The NSA/CSS Declassification Initiatives web page contains the following easily overlooked paragraph:

“An index of 4,923 entries containing approximately 1.3 million pages of previously declassified documents, which have been released to NARA is provided. The documents are from the pre-World War I period through the end of World War II.”

The links refers to a fascinating listing of cryptologic documents declassified by NSA/CSS in Project OPENDOOR (1996) and released to the U.S. National Archives and Record Administration (NARA) in Washington, D.C. In the very long, unsorted list one could easily overlook such gems as:

• William F. Friedman’s “Index of Coincidence and its Application to Cryptography” (# 504)

A Superb Cryptanalytical Guide to the Enigma Cipher Machine

Over the years I’ve come across many articles explaining how the Enigma cipher machine works. All too often I would feel, as a cryptanalyst, that many of the articles glossed over important features or handled them poorly.

Well, if you’re looking for an in-depth explanation of the Enigma, complete with a lucid mechanical description and mathematical underpinnings you can really sink your teeth into (and understand!) look no further. Check out Erik Vestergaard’s superb explanation of the Enigma’s mechanical, operational, and mathematical aspects. A Danish high school mathematics teacher, Vestergaard took his class on a study tour to London in 2007, and one of their stops included Bletchley Park. This site is a wonderful compilation of their experience in Bletchley, complete with mouth-watering, clear descriptions of how the Enigma works and how it was broken. Here’s a list of topics covered:

NSA/CSS declassified documents

The National Security Agency (NSA) and the Central Security Service (CSS) periodically release declassified documents or indexes to these documents to the public.  This is all part of the Freedom of Information Act (FOIA) which allows for the full or partial disclosure of previously unreleased information and documents controlled by the United States Government.

If cryptology and cryptanalysis are your cup of tea, just browse over to NSA’s Declassification Initiatives web page and dive in.   You’ll need a few hours to do this justice, so plan on returning a few times.

Here are some juicy finds: