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.
The Enigma machine is a cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military. The Enigma machine was considered so secure that it was used to encipher the most top-secret messages.
Ultra was the designation adopted by British military intelligence in June 1941 for wartime signals intelligence obtained by breaking high-level encrypted enemy radio and teleprinter communications at the Government Code and Cypher School (GC&CS) at Bletchley Park. Ultra eventually became the standard designation among the western Allies for all such intelligence. The name arose because the intelligence obtained was considered more important than that designated by the highest British security classification then used and so was regarded as being Ultra Secret. Several other cryptonyms had been used for such intelligence.
German submarine U-559 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.
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.
The Cipher Bureau was the interwar Polish General Staff's Second Department's unit charged with SIGINT and both cryptography and cryptanalysis.
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.
Cryptography was used extensively during World War II because of the importance of radio communication and the ease of radio interception. The nations involved fielded a plethora of code and cipher systems, many of the latter using rotor machines. As a result, the theoretical and practical aspects of cryptanalysis, or codebreaking, were much advanced.
Peter Frank George Twinn was a British mathematician, Second World War codebreaker and entomologist. The first professional mathematician to be recruited to GC&CS. Head of ISK from 1943, the unit responsible for decrypting over 100,000 Abwehr communications.
Hut 8 was a section in the Government Code and Cypher School (GC&CS) at Bletchley Park tasked with solving German naval (Kriegsmarine) Enigma messages. The section was led initially by Alan Turing. He was succeeded in November 1942 by his deputy, Hugh Alexander. Patrick Mahon succeeded Alexander in September 1944.
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.
Captain Raymond C. "Jerry" Roberts MBE was a British wartime codebreaker and businessman. During the Second World War, Roberts worked at the Government Code and Cypher School (GC&CS) at Bletchley Park from 1941 to 1945. He was a leading codebreaker and linguist, who worked on the Lorenz cipher system – Hitler's most top-level code.
Marian Adam Rejewski was a Polish mathematician and cryptologist who in late 1932 reconstructed the sight-unseen Nazi German military Enigma cipher machine, aided by limited documents obtained by French military intelligence. Over the next nearly seven years, Rejewski and fellow mathematician-cryptologists Jerzy Różycki and Henryk Zygalski developed and used techniques and equipment to decrypt the German machine ciphers, even as the Germans introduced modifications to their equipment and encryption procedures. Five weeks before the outbreak of World War II in Europe, the Poles shared their technological achievements with the French and British at a conference in Warsaw, thus enabling Britain to begin reading German Enigma-encrypted messages, seven years after Rejewski's original reconstruction of the machine. The intelligence that was gained by the British from Enigma decrypts formed part of what was code-named Ultra and contributed—perhaps decisively—to the defeat of Nazi Germany.
Enigma is a 1995 novel by Robert Harris about Tom Jericho, a young mathematician trying to break the Germans' "Enigma" ciphers during World War II. Jericho is stationed in Bletchley Park, the British cryptology central office, and is worked to the point of physical and mental exhaustion. The book was adapted to film in 2001.
Lieutenant Francis Anthony Blair Fasson,, known as Tony Fasson, was a Royal Navy officer. He was posthumously awarded the George Cross "for outstanding bravery and steadfast devotion to duty in the face of danger" when on 30 October 1942 in action in the Mediterranean Sea he captured codebooks vital for the breaking of the German naval "Shark" Enigma cipher from the sinking German submarine U-559.
Colin Grazier, GC was a sailor in the Royal Navy who was posthumously awarded the George Cross for the "outstanding bravery and steadfast devotion to duty in the face of danger" which he displayed on 30 October 1942 in action in the eastern Mediterranean when capturing codebooks vital for the breaking of the German naval "Shark" Enigma cipher from the sinking German submarine U-559.
Thomas William Brown GM was an English recipient of the George Medal, one of the youngest persons to have ever received that award. In October 1942, as a NAAFI canteen assistant, he was involved in the action between Petard and U-559, being one of three men to board the sinking submarine in an effort to retrieve vital documents, and was the only one of the three to survive. These documents greatly assisted Bletchley Park codebreakers in cracking the German Enigma code. After this heroic deed, it was revealed that he was underage to be at sea. He returned home to North Shields. In 1945 he died from injuries sustained while rescuing his sister Maureen from a house fire in North Shields Ridges Estate whilst on leave from HMS Belfast. His family were presented with his medal by King George VI in 1945, and later presented it to the NAAFI in 1985.
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.
X, Y & Z: The Real Story of How Enigma Was Broken is a 2018 book by Dermot Turing about the Enigma machine, which was used by Nazi Germany in World War II, and about the French, British, and Polish teams that worked on decrypting messages transmitted using the Enigma cipher.
