Alan Turing papers on code breaking released by GCHQ

[Gerald]

Two 70-year-old papers by Alan Turing on the theory of code breaking have been released by the government's communications headquarters, GCHQ.

It is believed Turing wrote the papers while at Bletchley Park working on breaking German Enigma codes.

A GCHQ mathematician said the fact that the contents had been restricted "shows what a tremendous importance it has in the foundations of our subject".

It comes amid celebrations to mark the centenary of Turing's birth.

The two papers are now available to view at the National Archives at Kew, west London.

GCHQ was able to approximately date the papers because in one example Turing had made reference to Hitler's age.

Maths problems

The papers, one entitled The Applications of Probability to Crypt, and the other entitled Paper on the Statistics of Repetitions, discuss mathematical approaches to code breaking.The principal challenge facing Turing, and those who worked at Bletchley Park, was cracking a secret code used by the Nazi government and military to scramble messages.

Establishing the settings the Germans' Enigma machines had used proved vital to the codebreaking effort, ultimately providing the Allies with a significant advantage, particularly against German submarine forces.

According to the GCHQ mathematician, who identified himself only as Richard, the papers detailed using "mathematical analysis to try and determine which are the more likely settings so that they can be tried as quickly as possible."

Bletchley Park went on to use bombes - large electro-mechanical machines worked on by Turing - to help identify the correct settings.

http://www.bbc.com/news/technology-17771962

Note: 19 April 2012 Last updated at 12:48 GMT