Hut 7

Hut 7 was a wartime section of the Government Code and Cypher School in Bletchley Park tasked with the solution of Japanese naval codes such as JN4, JN11, JN40, and JN25 [cite book |last=Loewe |first=Michael |chapter=Chapter 26: Japanese Naval Codes |editor=F. H. Hinsley and Alan Stripp |title=Codebreakers: The Inside Story of Bletchley Park |year=1993 |publisher=Oxford University Press |isbn=0-19-285304-X] [cite book |last=Denham |first=Hugh |chapter=Chapter 27: Bedford-Bletchley-Kilindini-Columbo |editor=F. H. Hinsley and Alan Stripp |title=Codebreakers: The Inside Story of Bletchley Park |year=1993 |publisher=Oxford University Press |isbn=0-19-285304-X] [cite journal |last=Scott |first=Norman |coauthors= |year=1997 |month=April |title=Solving Japanese Naval Ciphers 1943 – 45 |journal=Cryptologia |volume=21 |issue=2 |pages=pp149–157 |doi=10.1080/0161-119791885878] . The hut was headed by Hugh Foss who reported to Frank Birch, the head of Bletchley's Naval section.

Hut 7 supplied cryptanalysts and linguists to Bletchley’s front line station at Anderson Station, in Colombo, Ceylon (now Sri Lanka), and later Allidina School in Kilindini, Kenya.

Bletchley cooperated with units in Melbourne and Washington D.C. (the US Navy Code and Signals Section known as OP-20-G).

Pre-War Origins

Among the first challenges was overcoming the special kana and romaji Morse code system used by the Japanese. GCCS began breaking Japanese diplomatic traffic in the early 1920s [cite book |last=Smith |first=Michael |title=The Emperor's Codes: Bletchley Park and the Breaking of Japan's Secret Ciphers |year=2000 |publisher=Bantam Press |isbn=0-593-04642-0] . GCCS subsequently attacked the Naval Reporting Code, and General Operations Code.

The section was headed by William "Nobby" Clarke with Harry Shaw and Ernest Hobert-Hampden. These were later joined by Eric Nave, seconded from the Royal Australian Navy, John Tiltman, and Hugh Foss.

GCCS operated an intercept station in Hong Kong which later moved to Singapore and then to Colombo.

WWII Expansion

Potential linguists and cryptographers were recruited from universities of Cambridge and Oxford by referral through people like the Revd Martin Charlesworth, A.D. Lindsay, Dr C. P. Snow, and Theodore Chaundy. Candidates were interviewed and approved by a board that included Colonel Tiltman. Successful candidates received a final interview at Bletchley by a senior representative of their section.

At the outset of the war, Britain had few Japanese linguists and conventional wisdom held that it would require two years to produce qualified linguists for the war effort. In February 1942, an accelerated program was established to train linguists to assist with Japanese signals intelligence. Candidates were put through an intensive six month course taught by Captain Oswald Tuck, RN. The course was taught in various locations in Bedford including the Gas Company. The course produced linguists for the Navy, Army, Air Force, and Foreign Office. Some of the linguists were sent on to Bletchley, while others were sent to London to work with a Captain Kennedy.

Later cryptanalysts did not require linguistic training, so could be recruited and put to work directly. Some of these cryptanalysts received a shorter version of the Japanese language course.

The Japanese Naval Section was originally stationed at the Elmer School near Bletchley. By August 1942 the unit consisted of 40 people. The unit was moved inside Bletchley Park in September and again in February 1943 to Hut 7. The unit expanded (or moved) later to Block B.

Contributions

In addition to code books and manual ciphers, the Imperial Japanese Navy also utilized electric cipher machines known as JADE and CORAL using the same technology as PURPLE. While OP-20-G took the lead on these systems, Bletchley provided some contributions.

In 1921, GCCS was able to provide insight into the Japanese bargaining position at the Washington Naval Conference of the nine major powers and limit their ambitions.

Pre-war accomplishments were helped tremendously by the death of Emperor Taishō in 1926. The repetition of the formal announcement provided GCCS with cribs into almost every code in use. Later in 1934, Foss was able to break an early Japanese cipher machine.

Tiltman provided the major break into JN25 in 1939.

In early 1942, decrypts from Anderson gave advance warning of Vice Admiral Nagumo's Indian Ocean raid including a planned attack on Colombo. The warning allowed the British to limit damage, improve opposition, and evacuate the fleet and the cryptanalysts from Colombo to Kilindini.

In May 1945, the team at HMS Anderson successfully broke a message in JN25 that provided details of a supply convoy going from Singapore to the Andaman Islands. This message provided details that led to the sinking of the Japanese cruiser Haguro in the Battle of the Malacca Strait.

List of Hut 7 personnel

The following people served in Hut 7, HMS Anderson, and Kilindini:
* Sidney Abramson, translator at Anderson
* Brian Augarde, mathematician, sub-section chief at Bletchley, worked on JN11
* Peter Barnett, translator at Anderson
* Lieutenant-Commander Barnham, translator at Kilindini
* Charles Bawden, linguist at Anderson
* Ted Biggs, ex-diplomat, Kilindini, Anderson, and Melbourne
* Gerry Brennan, cryptanalyst at Bletchley, worked on JN40
* Leo Brouwer, from the Dutch Navy at Kilindini
* Maurice Burnett, linguist at Anderson
* John Catlow, linguist at Anderson
* Dudley Cheke, Kilindini
* Jon Cohen, linguist/cryptanalyst temporarily assigned to Diplomatic Section, later to Bletchley, and Kilindini
* Lieutenant-Commander E.H. Colgrave
* George Curnock, translator at Anderson and Kilindini
* Wynn Davies, translator/cryptanalyst at Bletchley and Kilindini
* Denny Denham, translator at Anderson
* Hugh Denham, cryptanalyst at Bletchley, Kilindini, and Anderson, worked on JN25
* Alan Douglas, linguist temporarily assigned to Diplomatic Section
* John English, sub-section chief at Bletchley
* Harry Field, Anderson
* Forman, Kilindini
* Hugh Foss, head of Hut 7
* Sergeant Harris-Jones, assistant translator at Bletchley
* Hubert Eustace Hooper, linguist at Anderson
* George Hunter, linguist at Anderson
* Hayden John, cryptanalyst, ran JN40 group at Bletchley
* Lieutenant-Commander Bruce Keith, translator at Bletchley
* Johnnie Lambert, cryptanalyst at Bletchley and Anderson
* Peter Laslett, cryptanalyst at Bletchley, worked on JN11
* Peter Lawrence, translator at Anderson
* John Lloyd, language instructor at Bletchley
* Michael Loewe, linguist/cryptanalyst at Bletchley and Kilindini
* John MacInnes, cryptanalyst at Kilindini
* Commander McIntyre RN, translator, at Kilindini and ran JN25 group at Bletchley
* Alan Merry, translator at Melbourne, Kilindini, and ran JN40 group at Anderson
* Milner, support at Anderson
* George Mitchell, Anderson
* Sandy Morris, Anderson
* Nichol, translator at Bletchley
* Commander Parsons RN, translator at Kilindini
* Jimmy Pollard, cryptanalyst at Bletchley, worked on JN40
* Pond, support at Anderson
* Fred Ponting, cryptanalyst at Bletchley, worked on JN11
* Norman Scott, mathematician / cryptanalyst at Bletchley and Anderson, worked on JN11 and JN25
* Sharman, cryptanalyst at Kilindini
* John Silkin, linguist at Anderson
* Stanton, cryptanalyst at Kilindini
* John Sutcliffe, cryptanalyst at Bletchley
* Patrick Taylor, mathematician at Bletchley
* Wilf Taylor, linguist at Anderson
* Captain Dick Thatcher RN, worked on JN 25 at Bletchley
* Brian Townend, cryptanalyst at Kilindini, contributed a break into JN40
* Richard Wolfe, Anderson
* Leslie Yoxall, cryptanalyst at Bletchley, previously working in Hut 8

References