Paper on statistics of repetitions London - Arabstoday The GCHQ, Britain\'s secretive spy agency, has released two papers written by World War II codebreaker Alan Turing, which were written whilst he was at Bletchley Park.  \"Because of continuing sensitivity the papers had been retained at GCHQ,\" a spokesperson for the agency said. \"But they have now been reassessed as suitable for release.\"  The first paper is called \"Paper on Statistics of Repetitions\". It shows Turing trying to work out the best statistical means of testing whether two cipher messages use the same key. The second is called \"The Applications of Probability to Cryptography\", and is about applying probability analysis to a wide range of cryptanalytic problems.  GCHQ could figure out date these papers were written because in one section Turing talks about using life expectancy to examine conditional probability, and writes \"Hitler is now age 52,\" as an example. This suggests that the paper was written between April 1941 and April 1942.  \"We are delighted to release these papers showing more of Alan Turing\'s pioneering research during his time at Bletchley Park,\" the spokesperson said. \"It was this type of research that helped turn the tide of war and it is particularly pleasing that we are able to share these papers during this centenary year.\"  Turing was a genius mathematician who played a pivotal role in World War II by cracking encrypted German messages. He is also considered a founding father of the modern computer, and a key figure in the research of artificial intelligence.  He was convicted for his homosexuality after the war, and took his own life through cyanide poisoning in 1954. In 2009, then-Prime Minister Gordon Brown apologised for Turing\'s \"appalling\" persecution, but in 2012 the government rejected a call to posthumously pardon Turing for his \"crime\".