Cryptanalysis of the Enigma Bletchley Park to describe the network that used the same Enigma setting sheets. Initially these were recorded using coloured pencils and were given the names "red", "light blue" etc., and later the names of birds such as "kestrel". During World War II the settings for most networks lasted for 24 hours, although towards the end of the war, some were changed more frequently. The sheets had columns specifying, for each day of the month, the rotors to be used and their positions, the ring positions and the plugboard connections. For security, the dates were in reverse chronological order down the
Mass surveillance in the United Kingdom and metadata for 30 days. A number of other GCHQ operations were revealed, including hacking into telecoms equipment, access to fibre-optic cables and programmes operated jointly with the NSA. GCHQ was originally established after the First World War as the "Government Code and Cypher School" (GC&CS) and was known under that name until 1946. During World War II, staff including Alan Turing worked on decoding the German Enigma machine, and many other foreign systems. In 1940, GC&CS was working on the diplomatic codes and ciphers of 26 countries, tackling over 150 diplomatic cryptosystems. After World War II, the United Kingdom