Known-plaintext attackThe known-plaintext attack (KPA) is an attack model for cryptanalysis where the attacker has access to both the plaintext (called a crib) and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books. The term "crib" originated at Bletchley Park, the British World War II decryption operation, where it was defined as:A plain language (or code) passage of any length, usually obtained by solving one or more cipher or code messages, and occurring or believed likely to occur in a different cipher or code message, which it may provide a means of solving.
Hut 8Hut 8 was a section in the Government Code and Cypher School (GC&CS) at Bletchley Park (the British World War II codebreaking station, located in Buckinghamshire) 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. Hut 8 was partnered with Hut 4, which handled the translation and intelligence analysis of the raw decrypts provided by Hut 8.
Ultraadopted 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 (Most Secret) and so was regarded as being Ultra Secret.
BuckinghamshireBuckinghamshire (ˈbʌkɪŋəmʃər,_-ʃɪər), abbreviated as Bucks, is a ceremonial county in South East England. It borders Northamptonshire to the north, Bedfordshire to the north-east, Hertfordshire to the east, Greater London to the south-east, Berkshire to the south, and Oxfordshire to the west. The largest settlement is the city of Milton Keynes (256,385). The county has an area of and a population of 808,666.
Rotor machineIn cryptography, a rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting messages. Rotor machines were the cryptographic state-of-the-art for much of the 20th century; they were in widespread use in the 1920s–1970s. The most famous example is the German Enigma machine, the output of which was deciphered by the Allies during World War II, producing intelligence code-named Ultra. The primary component of a rotor machine is a set of rotors, also termed wheels or drums, which are rotating disks with an array of electrical contacts on either side.
Enigma machineThe 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. The Enigma has an electromechanical rotor mechanism that scrambles the 26 letters of the alphabet.
