A Goldmine of GCCS and GCHQ Records (1914-1979)

September 13, 2009
The National Archives

The National Archives

Many thanks to Mike Cowan for a link to an internal sub-tree of The National Archives (UK) with a plethora of links to valuable cryptographic material related to the Government Code and Cypher School (GCCS) and Government Communications Headquarters (GCHQ) between the years 1914-1979.

Quoting from the web site, the site contains “general records of the Government Code and Cypher School (GCCS) and Government Communications Headquarters (GCHQ) relating to responsibilities for intercepting enemy communications, particularly during the Second World War, and for ensuring security of the government’s electronic communications“.

The records span the years 1914-1979 and included the following general categories:

  • Senior management papers
  • Soviet communications
  • Japanese military communications
  • Histories and personal papers
  • German military communications
  • Bulgarian, Croatian, French, Iranian, Italian Portuguese and Spanish communications
  • Diplomatic, commercial and meteorological communications
  • Liaison with allied organisations
  • Communications security
  • Field signals intelligence
  • Technical matters
  • Intercepted plain language communications
  • Wireless Telegraph Section
  • GC&CS Administration
  • Research Section

For those with access to the National Archives in London, there is material here to keep one busy for years.

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A Superb Cryptanalytical Guide to the Enigma Cipher Machine

April 24, 2009

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: Read the rest of this entry »