Bletchley Park is an English country house and estate in Bletchley, Milton Keynes (Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following 1883 for the financier and politician Sir Herbert Leon in the Victorian Gothic, Tudor, and Dutch Baroque styles, on the site of older buildings of the same name.
Fish was the UK's GC&CS Bletchley Park codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value (Ultra) was of the highest strategic value to the Allies. This traffic normally passed over landlines, but as German forces extended their geographic reach beyond western Europe, they had to resort to wireless transmission.
The bombe was an electro-mechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted secret messages during World War II. The US Navy and US Army later produced their own machines to the same functional specification, albeit engineered differently both from each other and from Polish and British bombes.
Cryptanalysis of the Enigma ciphering system enabled the western Allies in World War II to read substantial amounts of Morse-coded radio communications of the Axis powers that had been enciphered using Enigma machines. This yielded military intelligence which, along with that from other decrypted Axis radio and teleprinter transmissions, was given the codename Ultra.
Alfred Dillwyn "Dilly" Knox, CMG was a British classics scholar and papyrologist at King's College, Cambridge and a codebreaker. As a member of the Room 40 codebreaking unit he helped decrypt the Zimmermann Telegram which brought the USA into the First World War. He then joined the Government Code and Cypher School (GC&CS).
Enigma is a 2001 espionage thriller film directed by Michael Apted from a screenplay by Tom Stoppard. The script was adapted from the 1995 novel Enigma by Robert Harris, about the Enigma codebreakers of Bletchley Park in the Second World War.
Banburismus was a cryptanalytic process developed by Alan Turing at Bletchley Park in Britain during the Second World War. It was used by Bletchley Park's Hut 8 to help break German Kriegsmarine (naval) messages enciphered on Enigma machines. The process used sequential conditional probability to infer information about the likely settings of the Enigma machine. It gave rise to Turing's invention of the ban as a measure of the weight of evidence in favour of a hypothesis. This concept was later applied in Turingery and all the other methods used for breaking the Lorenz cipher.
Commander Alexander "Alastair" Guthrie Denniston was a Scottish codebreaker in Room 40, deputy head of the Government Code and Cypher School (GC&CS) and hockey player. Denniston was appointed operational head of GC&CS in 1919 and remained so until February 1942.
Hut 6 was a wartime section of the Government Code and Cypher School (GC&CS) at Bletchley Park, Buckinghamshire, Britain, tasked with the solution of German Army and Air Force Enigma machine cyphers. Hut 8, by contrast, attacked Naval Enigma. Hut 6 was established at the initiative of Gordon Welchman, and was run initially by Welchman and fellow Cambridge mathematician John Jeffreys.
Albert Leslie Yoxall was a British codebreaker at Bletchley Park during World War II. He devised a method to assist in solving Enigma messages which was dubbed Yoxallismus. After the war he worked at GCHQ until the mid-1970s.
Shaun Wylie was a British mathematician and World War II codebreaker.
Hugh Rose Foss was a British cryptanalyst. At Bletchley Park during World War II he made significant contributions both to the breaking of the German Enigma code and headed the section tasked with breaking Japanese Naval codes.
Rolf Noskwith was a British businessman who during the Second World War worked under Alan Turing as a cryptographer at the Bletchley Park British military base.
Hut 3 was a section of the Government Code and Cypher School (GC&CS) at Bletchley Park during World War II. It retained the name for its functions when it moved into Block D. It produced military intelligence codenamed Ultra from the decrypts of Enigma, Tunny and multiple other sources. Hut 3 thus became an intelligence agency in its own right, providing information of great strategic value, but rarely of operational use. Group Captain Eric Malcolm Jones led this activity from 1943 and after the war became deputy director, and in 1952 director of GCHQ. In July 1945, General Dwight D. Eisenhower Supreme Commander of Allied forces wrote to Sir Stewart Menzies, Chief of the British Secret Intelligence Service (MI6) saying inter alia:
"The intelligence that has emanated from you before and during this campaign has been of priceless value to me. It has simplified my task as commander enormously. It has saved thousands of British and American lives and, in no small way, has contributed to the speed with which the enemy was routed and eventually forced to surrender."
Hut 4 was a wartime section of the Government Code and Cypher School (GC&CS) at Bletchley Park tasked with the translation, interpretation and distribution of Kriegsmarine messages deciphered by Hut 8. The messages were largely encrypted by Enigma machines. As the Kriegsmarine operated Enigma more securely, Hut 8 had less information for Ultra than Hut 6 which handled Army and Air Force messages. Hut 4 also broke various hand cyphers and some Italian naval traffic.
Dennis William Babbage OBE was an English mathematician associated with Magdalene College, Cambridge, and with codebreaking at Bletchley Park during World War II.
Michael Arbuthnot Ashcroft (1920–1949) was a code breaker at Bletchley Park during the Second World War, working in Hut 8 under Alan Turing.
The Short Weather Cipher, also known as the weather short signal book, was a cipher, presented as a codebook, that was used by the radio telegraphists aboard U-boats of the German Navy (Kriegsmarine) during World War II. It was used to condense weather reports into a short 7-letter message, which was enciphered by using the naval Enigma and transmitted by radiomen to intercept stations on shore, where it was deciphered by Enigma and the 7-letter weather report was reconstructed.
Action This Day was a 1941 memorandum sent to Winston Churchill personally, as the Bletchley Park (BP) codebreaking establishment was short of staff in some critical areas. Their requirements were small, but as a small organisation their management did not have priority. Four senior heads of sections ("Huts") and their deputies wrote to Churchill, who had visited "BP" on 6 September 1941, where he made a speech saying he appreciated their work.
