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The Government Communications Headquarters (GCHQ) is a British Intelligence Agency responsible for providing Signals Intelligence (SIGINT) and Information Assurance to the UK Government and Armed Forces as required, under the guidance of the Joint Intelligence Committee . '''CESG''' (originally '''Communications-Electronics Security Group''') is the branch of GCHQ which works to secure the communications and information systems of the government and critical parts of UK national infrastructure. GCHQ was originally established after the First World War as the Government Code and Cypher School ('''GCCS''' or '''GC&CS'''), by which name it was known until 1946 . GCHQ is the responsibility of the UK Secretary Of State For Foreign And Commonwealth Affairs , but it is not a part of the Foreign Office , and its Director ranks as a Permanent Secretary . GOVERNMENT CODE AND CYPHER SCHOOL (GCCS) During World War I, Britain's Army and Navy had separate signals intelligence agencies, MI1b and NID25 (also known as Room 40) respectively.Johnson, p. 27 In 1919, the Cabinet's Secret Service Committee, chaired by Lord Curzon , recommended that a peace-time codebreaking agency should be created, a task given to the then- Director Of Naval Intelligence , Hugh Sinclair .Johnson, 1997, p. 44 Sinclair merged staff from NID25 and MI1b into the new organisation, which initially consisted of around 25-30 officers and a similar number of clerical staff.Johnson, 1997, p. 45 and Kahn, 1991, p. 82; these sources give different numbers for the initial size of the GCCS staff It was titled the "Government Code and Cypher School", a cover-name chosen by Victor Forbes of the Foreign Office .1 Alastair Denniston , who had been a member of NID25, was appointed as its operational head. It was initially under the control of the Admiralty , and located in Watergate House, Adelphi, London. Its public function was "to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision," but also had a secret directive to "study the methods of cypher communications used by foreign powers."Michael Smith, "GC&CS and the First Cold War," p. 16-17 in ''Action this Day'' edited by Ralph Erskine and Michael Smith, 2001 GCCS officially formed on 1 November 1919 ,Kahn, 1991, p. 82 and produced its first decrypt on 19 October . By 1922, the main focus of GCCS was on diplomatic traffic, with "no service traffic ever worth circulating"Alastair G. Denniston, "The Government Code and Cypher School Between the Wars", ''Intelligence and National Security'' 1(1), January 1986, pp 48-70 and so, at the initiative of Lord Curzon, it was transferred from the Admiralty to the Foreign Office .Smith, 2001, pp. 20-21 GCCS came under the supervision of Hugh Sinclair, who by 1923 was both the Chief of SIS and Director of GCCS. In 1925, both organisations were co-located on different floors of Broadway Buildings, opposite St James' Park . Messages decrypted by GCCS were distributed in blue jacketed files that became known as "BJs".Smith, 2001, pp. 18-19 In the 1920s, GCCS was successfully reading Soviet Union diplomatic ciphers. However, in May 1927, during a row over clandestine Soviet support for the General Strike and the distribution of subversive propaganda, Prime Minister Stanley Baldwin made details from the decrypts public, prompting the Soviet to change their systems to more secure schemes, including the One-time Pad . Before World War II , GCCS was a relatively small department, and staff included Alastair Denniston , Oliver Strachey , Dilly Knox , John Tiltman , Edward Travis , Ernst Fetterlein , Josh Cooper and Hugh Foss . During the Second World War , GCCS was based largely at Bletchley Park , reading, most famously, the German Enigma Machine ciphers, but also a large number of other systems. In 1940 , GCCS was working on the diplomatic codes and ciphers of 26 countries, tackling over 150 diplomatic cryptosystems.David Alvarez, GC&CS and American Diplomatic Cryptanalysis GCCS was renamed the "Government Communications Headquarters" in June 1946.2 AFTER WORLD WAR II |
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