The Bletchley Park Codebreakers
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Page 9 Those working on the Japanese diplomatic material: John Ferris, ‘From Broadway House to Bletchley Park: The Diary of Captain Malcolm D. Kennedy, 1934–46’, Intelligence and National Security, 4(3) (1989), 430.
Page 10 Details of the Type A machine: Nave, ‘An Australian’s Unique Naval Career’, pp. 338–45. Kenworthy: Johnson, Evolution; H. C. Kenworthy, ‘A Brief History of Events leading to the Growth of the “Y” Service’ (PRO HW 3/81), 9. The Americans broke the Type A machine, which they called Red, in late 1936: see Safford, ‘History of Japanese Cipher Machines’, 1–2; Frank B. Rowlett, The Story of Magic: Memoirs of an American Cryptologic Pioneer (Aegean Park Press, Laguna Hills, 1998), pp. 112–32.
Page 11 Setting up of FECB: see R. T. Barrett, ‘HMS Anderson and Special Intelligence in the Far East’ (PRO HW 4/24), 1–3; Paymaster-Captain H. L. Shaw, ‘History of the Far East Combined Bureau’ (PRO HW 4/25), 1–3.
Page 12 Tiltman breaking army codes: Tiltman, ‘Some Reminiscences’, 8–9.
Page 13 Tiltman break into JN-25: Shaw, ‘History of the Far East Combined Bureau’, 14–15, 18; Ralph Erskine and Peter Freeman, ‘Brigadier John Tiltman: One of Britain’s Finest Cryptologists’, Cryptologia, 27 (2003), 289.
Page 14 Moves of FECB and Bletchley Park: Barrett, ‘HMS Anderson and Special Intelligence in the Far East’, 4; Shaw, ‘History of the Far East Combined Bureau’, 15–17; Ferris, ‘From Broadway House to Bletchley Park’; Michael Smith, Station X: The Codebreakers of Bletchley Park (Channel 4 Books, London, 1998), pp. 1–3.
Page 15 FECB JN-25 capabilities: ‘Collaboration of British and US Radio Intelligence’ (PRO ADM 223), 1; Lt.-Cmdr. Neil Barham, ‘Japanese Cipher Notes’ (PRO ADM 223/496), 3; Shaw, ‘History of the Far East Combined Bureau’, 23–4.
Page 16 Break into Purple: Rowlett, The Story of Magic, pp. 151–9.
Page 17 American gift of a Purple machine: ‘History of the Signal Security Agency’, Vol. Two, ‘The General Cryptanalytical Problems’ (NACP, RC 457 SRH 361), 13.
Page 18 Details of co-operation: ‘Report of Technical Mission to England’, A. Sinkov and Leo Rosen, 11 April 1941, ‘Army and Navy Comint Regs & Papers’ (NACP HCC Nr. 4632).
Page 19 Barham on introduction of JN-25B: Barham, ‘Japanese Cipher Notes’, 3.
Page 20 Early co-operation between FECB and Corregidor: ‘Collaboration of British and US Radio Intelligence’ (PRO ADM 223/496), 1; Shaw, ‘History of the Far East Combined Bureau’, 31–3; Nave, ‘An Australian’s Unique Naval Career’, pp. 398–9.
Page 21 Exchanges with US Army and Dutch: ‘History of the Far East Combined Bureau’, 31–3.
Page 22 Nave return and exchange deal: Nave, ‘An Australian’s Unique Naval Career’, pp. 405–11, 429–32; Nave to Shaw, 28 August 1941 (PRO ADM 223/496); Central Bureau Technical Records. Part A – Organisation (in author’s possession), 1; Smith, The Emperor’s Codes, p. 80.
Page 23–24 Oshima messages and GC&CS difficulty in making Whitehall believe that Germany was about to attack Russia: Carl Boyd, Hitler’s Japanese Confidant: General Oshima Hiroshi and Magic Intelligence (University Press of Kansas, Kansas, 1993), pp. 18–21; F. H. Hinsley, British Intelligence in the Second World War (revised abridged edition) (HMSO, London, 1994), pp. 106–9; Smith, Station X, p. 73.
Page 25 Oshima messages revealing German attempts to draw Japan into war with Russia and Japanese intention to attack Indochina: diary of Captain Malcolm D. Kennedy (Kennedy Papers, University of Sheffield Library), 13–22 July 1941.
Page 26 FECB tracking of Japanese Fleet: ‘Pearl Harbour and the Loss of Prince of Wales and Repulse’ (PRO ADM 223/494), 2–8.
Page 27 ‘intelligence covering a wide field’: Barham, ‘Japanese Cipher Notes’, 3.
Page 28 warnings to the Japanese embassy in London to await the Winds messages: PRO HW 1/240 and HW 1/303.
Page 29 Additive and call sign changes: Smith, The Emperor’s Codes, pp. 98–9.
Page 30 Winds message received: Shaw, ‘History of the Far East Combined Bureau’, 28.
Page 31–32 British surprise: Nave, ‘An Australian’s Unique Naval Career’, pp. 420–2; diary of Captain Malcolm D. Kennedy, 7 December 1941.
Page 33 FECB move to Colombo and capture of Hong Kong: Shaw, ‘History of the Far East Combined Bureau’, 30, 35–6; Peter Elphick, Far Eastern File: The Intelligence War in the Far East 1930–1945 (Coronet, London, 1997), pp. 96–7.
Page 34 MacInnes on disruption caused by move from Singapore: John MacInnes, ‘History of Anderson’, chap. IX, Production (PRO HW 4/25), 119–21.
Page 35 Nave on Fabian security issues: Nave, ‘An Australian’s Unique Naval Career’, pp. 409–11, 429–32, 449–51; Sharon A. Maneki, The Quiet Heroes of the Southwest Pacific Theater (NSA, Fort Meade), pp. 63–6, 88–91.
Page 36 MacInnes on advantages from Japanese failure to replace JN-25B book: MacInnes, ‘History of Anderson’, chap. IX, Production, 138–9.
Page 37 Codebreakers predict attack on Colombo: Hugh Denham, ‘Bedford-Bletchley-Kilindini-Colombo’, in F. H. Hinsley and Alan Stripp (eds), Codebreakers: The Inside Story of Bletchley Park (OUP, Oxford, 1993), pp. 274–5; MacInnes, ‘History of Anderson’, chap. IX, Production, 131.
Page 38 MacInnes on further disruption caused by move to Kilindini: ibid., 119.
Page 39 Midway: For a fuller description of the role of Sigint in the Battle of Midway, see Smith, The Emperor’s Codes, pp. 134–41.
Page 40 Problems caused by lack of co-operation from Fabian unit: Benson, A History of US Communications Intelligence during World War II, pp. 87–8; Maneki, The Quiet Heroes of the Southwest Pacific Theater, pp. 88–91.
Page 41 Senior officer on US view of co-operation: Elphick, Far Eastern File, p. 399.
Page 42 Possibility of British breaking with US: Birch to Hastings, 2 July 1944 (PRO HW 14/142).
Page 43 Breaking of JN-40 and other codes/ciphers by Kilindini: MacInnes, ‘History of Anderson’, chap. IX, Production, 138–9.
Page 44 Tiltman on Japanese military attaché code: Tiltman, ‘Some Reminiscences’, 10–11.
Page 45 Setting up of Japanese military section under direction of Tiltman: Nigel de Grey, ‘History of Air Sigint’, chap. IX, The Japanese War (PRO HW 3/102), 517–20; ‘History of Military Intelligence Section at Bletchley Park’ (PRO HW 3/156), 25–6.
Page 46 Tiltman sets up Japanese courses: Tiltman, ‘Some Reminiscences’, 9–10.
Page 47 Locations of various British outposts: Smith, The Emperor’s Codes, pp. 231–2.
Page 48 Breaking of Water Transport Code: author’s various correspondence with Joe Richard, January–February 2000; Alan Stripp, Codebreaker in the Far East (Frank Cass, London, 1989), p. 71; Hugh Skillen, Spies of the Airwaves (Hugh Skillen, London, 1987), p. 517; Maclnnes, ‘History of Anderson’, chap. IX, Production, 139.
Page 49 Yamamoto shoot-down: John Prados, Combined Fleet Decoded (Random House, New York, 1995), pp. 459–63; Maneki, The Quiet Heroes of the Southwest Pacific Theater, p. 90.
Page 50 Bletchley success against Army Air code: Edward J. Drea, ‘Were The Japanese Army Codes Secure?’, Cryptologia, 19 (1995), 122; interview with Maurice Wiles, 22 December 1999; Minutes of Conference on Japanese Military Ciphers held at Bletchley Park, 7 May 1943–17 May 1943 (PRO WO 208/5074).
Page 51 Conference on army codes: De Grey, ‘History of Air Sigint’, chap. IX, ‘The Japanese War’, 517–20; Minutes of Conference on Japanese Military Ciphers held at Bletchley Park, 7 May 1943–17 May 1943.
Page 52 Expansion of Japanese sections: Smith, The Emperor’s Codes, pp. 186–7.
Page 53 Move to Colombo and Redman softens attitude to co-operation: R. T. Barrett, ‘HMS Anderson and Special Intelligence in the Far East’ (PRO HW 4/24), 8; Benson, A History of US Communications Intelligence during World War II, p. 119.
Page 54 Saunders on FRUMEL: Cdr. Malcolm Saunders, ‘Report on Visit to US and Other Signals Intelligence Centres’, 28 December 1943 (PRO HW 223/496), 3.
Page 55 Hinsley: Birch to Washington, 28/5/44 (PRO HW 14/142); Robert Louis Benson, A History of US Communications Intelligence during World War II (NSA, Fort Meade), pp. 120–1.
Page 56 Alexander role in breaking of Coral: Smith, The Emperor’s Codes, pp. 218–20.
Page 57 codebooks found at Sio: Central Bureau Technical Records. Part A – Organization, 6; ‘History of Military Intelligence Section at Bletchley Park’ (PRO HW 3/156), 42.
Page 58 Melinsky quotes: Hugh Melinsky, A Code-breaker’s Tale (Lark’s Press, Denham, 1998), pp. 19–67.
Page 59 BULBUL break: Leonard ‘Joe’ Hooper to Arlington Hall, 14 September 1944 (PRO HW 14/142).
Page 60 Kerry quote: interview with Sir Michael Kerry, 15 February 2000.
CHAPTER 9 SOLVING JN-25 AT BLETCHLEY PARK: 1943–45
Edward Simpson would like to point out that this account of Bletchley Park’s cryptanalytical work on the main Japanese naval cipher JN-25 between August 1943 and August 1945 was written from memory in 2010, and by reference to the ‘History of the Fleet General Purpose System (JN-25): Cryptographic Party’, an internal GC&CS history which he wrote in August 1945. This was released to the PRO in 2009 as HW 8/149. It is not a history of the cryptanalysis. That is believed to be in a separate internal history which he and Ian Cassels wrote: ‘GC&CS Naval Cryptanalytic Studies Volume IX: The Japanese Fleet General Purpose System II’, which is still withheld as HW 43/34. Simpson is most grateful to both editors for the opportunity to put this part of Bletchley Park’s work on the record, he believes for the first time, and for much help in preparing it.
Page 1 The Hagelin C-38 cipher was read currently: For the intelligence derived from the Italian Hagelin traffic, see ‘C38m’ in the index to F. H. Hinsley, with E. E. Thomas, C. F. G. Ransom and R. C. Knight, British Intelligence in the Second World War: Its Influence on Strategy and Operations, vol. 2 (London: Her Majesty’s Stationery Office, 1981).
Page 2 ‘Commander Belfield RN … but without any known Christian name’: Editor’s note: Belfield’s Christian name was unknown at the time to Simpson and his colleagues but should be recorded as Felix.
Page 3 divisible by three in virtually all: in the N code scanning by three disappeared. Instead, no group contained zeros
Page 4 the traffic went first to the Processing Party which served all the Japanese Naval parties. This was led by Mrs E. Parsons: see ‘History of the Japanese Naval Subtractor Systems (JN-11, JN-23, JN-25): Processing Party’, by Mrs E Parsons, PRO HW 8/152.
Page 5 ‘Freebornery’ named after its head ‘Mr Freeborn’: Frederic Freeborn.
Page 6 we relied heavily on the ‘Freebornery’ to provide: for an account of the Freebornery by Mr Freeborn’s Deputy, Ronald Whelan, ‘The Use of Hollerith Equipment in Bletchley Park’, see PRO HW 25/22.
Page 7 Referring to an earlier era… Gordon Welchman wrote: see Gordon Welchman, The Hut Six Story: Breaking the Enigma Codes (Allen Lane, London, 1982), p. 181
Page 8 Frank Birch: Frank Birch The Official History of British Sigint 1914–1945 (John Jackson (ed.)) (Military Press: Milton Keynes, 2007), 2: 101 (a published version of ‘The History of British Sigint 1914–1945. Vol II’, PRO HW 43/2).
Page 9 The resolution of our role came on 23 October 1944 with the signing … of an Agreement: see Ralph Erskine: ‘The 1944 Naval BRUSA Agreement and its Aftermath’, Cryptologia, 30 (2006), 1.
Page 10 British keys proved to be: ‘History of GYP-1’, 127: NACP, RG 38, CNSG Library, Box 116, CNSG 5750/202. The Washington method was a weighting process based upon the statistical effects of the code’s scanning properties.
Page 11 would be good to know how they did it: perhaps this is in the internal history ‘GC&CS Naval Cryptanalytic Studies Volume IX: The Japanese Fleet General Purpose System II’ (see introductory note above).
CHAPTER 10 MOST HELPFUL AND CO-OPERATIVE: GC&CS AND THE DEVELOPMENT OF AMERICAN DIPLOMATIC CRYPTANALYSIS, 1941–2
David Alvarez would like to thank Ralph Erskine and Michael Smith for providing copies of certain documents from the Public Record Office.
Page 1 a staff of about sixty-five, etc.: GC&CS annual report for 1940, Diplomatic sections, 13 January 1941 (PRO HW 14/11).
Page 2 The Foreign Office received, etc.: D & R Berkeley Street, Diplomatic Section [nd] (PRO HW 3/162).
Page 3 recipient was Major Anthony Blunt: Chart, Sources of Material (as at 31 March 1944) (PRO HW 3/32).
Page 4 The Russians have claimed: David Kahn, ‘Soviet Comint in the Cold War’, Cryptologia, 22 (1998), 11.
Page 5 On 27 July 1942: Carl Boyd, Hitler’s Japanese Confidant: General Oshima Hiroshi and Magic Intelligence, 1942–1945 (University Press of Kansas, Lawrence, 1993) p. 63; Kahn, ‘Soviet Comint in the Cold War’, 13.
Page 6 brief existence in the 1920s: David Alvarez, Secret Messages: Codebreaking and American Diplomacy, 1930–1945 (University Press of Kansas, Lawrence, 2000), p. 38.
Page 7 five Japanese diplomatic ciphers: ‘History of the Signal Security Agency, vol. 2: The General Cryptanalytic Problem’, pp. 31–2 (NACP, RG 457, SRH-361).
Page 8 at least one Mexican cipher: Alvarez, Secret Messages, p. 54.
Page 9 low-grade consular and administrative traffic: ibid.
Page 10 neither of these systems was readable: ‘Italian Codes and Ciphers, 1939–1943’ (HCC Box 1388).
Page 11 still struggled with its target: Alvarez, Secret Messages, p. 61.
Page 12 was hardly better: ibid., p. 62.
Page 13 window into Japanese diplomacy had closed: ibid., p. 63.
Page 14 joint staff conference in London: Alan Harris Bath, Tracking the Axis Enemy: The Triumph of Anglo-American Naval Intelligence (University Press of Kansas, Lawrence, 1998), p. 25.
Page 15 exchange information on their cryptanalytic operations: Alvarez, Secret Messages, p. 76.
Page 16 ‘please expedite reply’: quoted in Robert Louis Benson, A History of US Communications Intelligence during World War II (NSA, Fort Meade), p. 17.
Page 17 concerning specific foreign codes and ciphers: Alvarez, Secret Messages, pp. 78–9. The Akin-Friedman memorandum is undated but is generally thought to have been written on or about 1 September 1940.
Page 18 a few Red Army and Comintern systems: Robert Louis Benson and Cecil Phillips, History of Venona (NSA, Fort Meade, 1995), 1: 29. I am indebted to Lou Benson for arranging for the declassification of parts of this multi-volume history.
Page 19 it was the breakthrough: Stephen Budiansky, Battle of Wits: The Complete Story of Codebreaking in World War II (Free Press, New York, 2000), pp. 165–6.
Page 20 quashed their opposition: Alvarez, Secret Messages, p. 83.
Page 21 ‘have a look around’: Prescott Currier oral history, NSA-OH-38-80 (National Cryptologic Museum Library, NSA, Fort Meade).
Page 22 ‘almost empty’: Donald Gish, ‘A Cryptologic Analysis’, International Journal of Intelligence and Counterintelligence, 6(4) (1993), 387, fn 17. By January 1941, OP-20-G had recovered only 3 per cent of the values in JN-25B.
Page 23 had been working this system: Michael Smith, The Emperor’s Codes: Bletchley Park and the Breaking of Japan’s Secret Ciphers, (Dialogue, London, 2010) pp. 78–9.
Page 24 ‘a fairly large staff: [Abraham Sinkov], ‘Report of Cryptographic Mission’ (NACP HCC Box 1296).
Page 25 committed to the Italian problem: ‘Cryptographic Codes and Ciphers: Italian’ (NACP HCC Box 1388); ‘Annual Report of the Chief Signal Officer and Miscellaneous Studies, FY 1942–1943’ (NACP HCC Box 832).
Page 26 abandoned work on these formidable ciphers: ‘Report on German Diplomatic Section’, 8 January 1941 (PRO HW 14/4).
Page 27 ciphers used by Germany in the First World War: Alvarez, Secret Messages, p. 130.
Page 28 ‘all our technical documents’: ‘Report by Lieut. Colonel J. H. Tiltman on his visit to North America during March and April 1942’ (PRO HW 14/46). The material passed by Tiltman to the Americans is enumerated
in this report.
Page 29 ‘results from me’: [Solomon Kullback], ‘The British GC&CS’, 1 August 1942, 6–7, Sinkov Papers (NACP HCC Box 1413).
Page 30 had been especially fruitful: ‘Notes on Diplomatic Liaison with U.S.’, 8 March 1942 (PRO HW 14/46); ‘Report on present position of legibility of Foreign Government Cyphers’, 25 July 1942 (PRO HW 14/38).
Page 31 ‘we wonder if they are actually deeply interested’: Denniston to Stevens, 22 December 1942 (PRO HW 14/62).
Page 32 direct requests for assistance: for a survey of exchanges between Berkeley Street and Arlington Hall in the period 1943–5, see ‘Governments on which there has been no substantial impediment to liaison’, Clark Files (British Liaison, 1940–1945) (NACP HCC Box 1413).
Page 33 including American policies: Cadogan to ‘C, 3 July 1944 (PRO HW 37/4).
Page 34 South American systems: for an overview of areas in which collaboration faltered, see ‘Governments on which there is a present obstacle to liaison’, Clark Files (British Liaison, 1940–1945) (NACP HCC Box 1413).
Page 35 Russian civil traffic: Benson and Phillips, History of Venona, p. 31.
Page 36 ‘very great indeed’: (NACP, RG 457. SRH-349), ‘Achievements of the Signal Security Agency in World War 11’, 9.
CHAPTER 11 BREAKING GERMAN NAVAL ENIGMA ON BOTH SIDES OF THE ATLANTIC
Ralph Erskine wishes to thank David Alvarez, Stephen Budiansky and Frode Weierud for supplying some of the documents used in Chapter 11.
Page 1 Even Knox found: Dillwyn Knox, undated notes on senior staff [nd c. end 1939] (PRO HW 14/1).
Page 2 ‘almost as conveniently as if…’: C. H. O’D. Alexander, ‘Cryptographic History of Work on the German Naval Enigma’, 90 (PRO HW 25/1).
Page 3 were never broken: Hinsley et al., British Intelligence, 2: 664.