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In the history of cryptanalysis, Room 40, also known as 40 O.B. (Old Building) (latterly NID25) was the section in the British Admiralty most identified with the British cryptoanalysis effort during the First World War. Room 40 was a group formed in October 1914, shortly after the start of the war. Admiral Oliver, the Director of Naval Intelligence, gave intercepts from the German radio station at Nauen, near Berlin, to Director of Naval Education Alfred Ewing, who constructed ciphers as a hobby. Ewing recruited civilians such as William Montgomery, a translator of theological works from German, and Nigel de Grey, a publisher. The basis of Room 40 operations evolved around a German naval codebook, the ''Signalbuch der Kaiserlichen Marine'' (SKM), and around maps (containing coded squares), which Britain's Russian allies had passed on to the Admiralty. The Russians had seized this material from the German cruiser ''Magdeburg'' when it ran aground off the Estonian coast on 26 August 1914. Russian personnel recovered two of the four copies that the warship had carried: they retained one and passed the other to the British. In October 1914 the British also obtained the Imperial German Navy's ''Handelsschiffsverkehrsbuch'' (HVB), a codebook used by German naval warships, merchantmen, naval zeppelins and U-Boats: the Royal Australian Navy seized a copy from the Australian-German steamer ''Hobart'' on 11 October. On 30 November a British trawler recovered a safe from the sunken German destroyer ''S-119'', in which was found the ''Verkehrsbuch'' (VB), the code used by the Germans to communicate with naval attachés, embassies and warships overseas. In March 1915 a British detachment impounded the luggage of Wilhelm Wassmuss - a German agent in Persia - and shipped it, unopened, to London, where then-Director of Naval Intelligence Admiral Sir William Reginald Hall discovered that it contained the German Diplomatic Code Book, Code No. 13040.〔(iranica )〕 The function of the Room 40 program was compromised by the Admiralty's insistence upon interpreting Room 40 information in its own way. Room 40 operators were permitted to decrypt, but not to interpret the information they acquired. The section retained "Room 40" as its informal name even though it expanded during the war and moved into other offices. It has been estimated that Room 40 decrypted around 15,000 German communications, the section being provided with copies of all intercepted communications traffic, including wireless and telegraph traffic. Alfred Ewing directed Room 40 until May 1917, when direct control passed to Captain (later Admiral) Reginald 'Blinker' Hall, assisted by William Milbourne James. ==Origins== In 1911, a committee of the Committee of Imperial Defence on cable communications concluded that in the event of war with Germany, German-owned submarine cables should be destroyed. In the early hours of 5 August 1914, the cable ship ''Alert'' located and cut Germany's five trans-Atlantic cables, which ran down the English Channel. Soon after, the six cables running between Britain and Germany were cut. As an immediate consequence, there was a significant increase in cable messages sent via cables belonging to other countries, and cables sent by wireless. These could now be intercepted, but codes and ciphers were naturally used to hide the meaning of the messages, and neither Britain nor Germany had any established organisations to decode and interpret the messages. At the start of the war, the navy had only one wireless station for intercepting messages, at Stockton. However, installations belonging to the Post Office and the Marconi Company, as well as private individuals who had access to radio equipment, began recording messages from Germany. Intercepted messages began to arrive at the Admiralty intelligence division, but no one knew what to do with them. Rear-Admiral Henry Oliver had been appointed Director of the Intelligence division in 1913. In August, 1914, his department was fully occupied with the war and none had experience of codebreaking. Instead he turned to a friend, Sir Alfred Ewing, the Director of Naval Education (DNE), who previously had been a professor of engineering with a knowledge of radio communications and who he knew had an interest in ciphers. It was not felt that education would be a priority during the expected few months duration of the war, so Ewing was asked to set up a group for decoding messages. Ewing initially turned to staff of the naval colleges Osborne and Dartmouth who were currently available, due both to the school holidays and to naval students having been sent on active duty. Alastair Denniston had been teaching German but later became second in charge of Room 40, then becoming Chief of its successor after the First World War, the Government Code and Cypher School (located at Bletchley Park during the Second World War). Others from the schools worked temporarily for Room 40 until the start of the new term at the end of September. These included Charles Godfrey, the Headmaster of Osborne (whose brother became head of naval Intelligence during the Second World War), two Naval instructors, Parish and Curtiss and scientist and mathematician Professor Henderson from Greenwich Naval College. Volunteers had to work at codebreaking alongside their normal duties, the whole organisation operating from Ewing's ordinary office where codebreakers had to hide in his secretary's room whenever there were visitors concerning the ordinary duties of the DNE. Two other early recruits included R. D. Norton, who had worked for the Foreign Office, and Lord Herschell, who was a linguist, an expert on Persia, and an Oxford graduate. None of the recruits knew anything about codebreaking, but were chosen for a knowledge of German and a certainty they could keep the matter secret. A similar organisation had begun in the Military Intelligence department of the War Office, which become known as MI1b, and Colonel Macdonagh proposed that the two organisations should work together. Little success was achieved except to organise a system for collecting and filing messages until the French obtained copies of German military ciphers. The two organisations operated in parallel, decoding messages concerning the Western Front. A friend of Ewing's, a barrister by the name of Russell Clarke, plus a friend of his, Colonel Hippisley, approached Ewing to explain that they had been intercepting German messages. Ewing arranged for them to operate from the coastguard station at Hunstanton in Norfolk, where they were joined by another volunteer, Leslie Lambert (later becoming known as a BBC broadcaster under the name A. J. Alan). Hunstanton and Stockton formed the core of the interception service (known as 'Y' service), together with the post office and Marconi stations, which grew rapidly to the point it could intercept almost all official German messages. At the end of September, the volunteer schoolmasters returned to other duties except for Denniston, but without a means to decode German naval messages there was little specifically naval work to do. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Room 40」の詳細全文を読む スポンサード リンク
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