Page 17 around 7 January 1940: Knox, letter, 7 January 1940.
Page 18 threaten to resign: ibid.
Page 19 decision taken in early December: ‘De Grey’s History of Air Sigint’, 91.
Page 20 first wartime key: F. H. Hinsley et al., British Intelligence in the Second World War (HMSO, London, 1988), 3(2): 952 states that 6 and 17 January and 25 October 1939 were broken before 23 January. However, those dates of breaking do not quite coincide with a detailed list maintained by Colonel Gwido Langer, the head of the Polish Cipher Bureau: see Tables 1 and 2 in Gordon Welchman, ‘From Polish Bomba to British Bombe: The Birth of Ultra’, Intelligence and National Security, 1(1) (1986), 104.
Page 21 might have changed: ‘De Grey’s History of Air Sigint’, 90.
Page 22 about fifty daily keys: Hinsley et al., British Intelligence, 1:108.
Page 23 until it went out of service: ‘De Grey’s History of Air Sigint’, 102.
Page 24 ‘unversed in the ways of military intelligence’: Ralph Bennett, Behind the Battle: Intelligence in the War with Germany, 1939–45 (Sinclair-Stevenson, London, 1994), p. 72.
Page 25 were insufficiently organized: Hinsley et al., British Intelligence, 1: 137.
Page 26 made Enigma vulnerable: TICOM I-45 (OKW/Chi Cryptanalytic Research on Enigma, Hagelin and Cipher Teleprinter Machines – by Dr Erich Hüttenhain and Dr Fricke), 4.
Page 27 Red for 20 May: ‘De Grey’s History of Air Sigint’, 105.
Page 28 discovered by Knox: minute of 25 January 1940, by Denniston to ‘C (PRO HW 14/3); [Denniston], telegram, 7 February 1940, apparently to Bertrand (PRO HW 25/12).
Page 29 1,000 messages on Red: minute, 26 August 1940, by Hut 6 cryptanalysts, 7 (PRO HW 14/6).
Page 30 Whitehall was ready: Hinsley et al., British Intelligence, 1: 144.
Page 31 completely vulnerable: Knox to Denniston, letter [nd; on Hotel Bristol, Warsaw, notepaper].
Page 32 before 1 November 1939: A. D. Knox, and others, memorandum, 1 November 1939 (PRO HW 14/2).
Page 33 14 March 1940: ‘Squadron-Leader Jones’ Section’, 1 (PRO HW 3/164).
Page 34 much easier to devise: C. A. Deavours and Louis Kruh, The Turing Bombe: Was it Enough?’, Cryptologia, 24 (1990), 331.
Page 35 99 per cent: Donald W. Davies, ‘Effectiveness of the Diagonal Board’, Cryptologia, 23 (1999), 131.
Page 36 thirty-five to fifty minutes: W. F. Friedman, ‘Report on E Operations of the GC&CS at Bletchley Park’, 59 (NACP HCC Box CBTE 28, Nr. 3620).
Page 37 preliminary check: ‘Operations of the 6812th Signal Security Detachment’, 14 (NACP HCC Box 970, Nr. 2943).
Page 38 peak of 9,064: ‘Squadron-Leader Jones’ Section’, 9 (PRO HW 3/164).
Page 39 US Navy bombes: see Chapter 11.
Page 40 for about twenty-five days: DMI, minute, 19 March 1942, ‘Brief for C.I.G.S. on 20.3.42’ (PRO WO 208/5027).
Page 41 7 per cent of the total bombe time: memorandum, 3 May 1942, ‘Proportion of Bombe Time Spent on Various Colours for April, 1942’ (PRO HW 14/36).
Page 42 justified priority being given to the naval work: Hinsley et al., British Intelligence, 2: 216 fn.
Page 43 five ‘bombe controllers’: C. H. O’D. Alexander, ‘Cryptographic History of Work on the German Naval Enigma’, 37 (PRO HW 25/1).
Page 44 fifty-eight ‘standard’ three-rotor bombes: Friedman, ‘Report on E Operations’, 60.
Page 45 1,675 Wrens: ‘Squadron-Leader Jones’ Section’, 14 (PRO HW 3/164).
Page 46 6812th Signal Security Detachment: memorandum, 15 June 1945, ‘Operations of the 6812th Signal Security Detachment’.
Page 47 from October onwards: ‘Times’, 17 February 1945 (PRO HW 14/122).
Page 48 average of 71.5 runs: ‘Figures Relating to the Use of Standard Type Bombes During April, 1945’ (PRO HW 14/126).
Page 49 between twenty and thirty letters: S. Milner-Barry, memorandum of 25 July 1944, ‘Operation D’, 3 (PRO HW 14/108).
Page 50 ‘Sultan’s Meldung’: Friedman, ‘Report on E Operations’, 46–8; ‘Cryptanalytic Report on the Yellow Machine’, 84 (NACP HCC Box 1009, Nr. 3175).
Page 51 crib on Phoenix: ibid., 88.
Page 52 To Welchman’s regret: Friedman, ‘Report on E Operations’, 7.
Page 53 reluctance to make the Stecker: ibid., 38; ‘Cryptanalytic Report on the Yellow Machine’, 42.
Page 54 basic mistakes: Friedman, ‘Report on E Operations’, 36; ‘Cryptanalytic Report on the Yellow Machine’, 71.
Page 55 indirect warnings: X-Gerät to be jammed: Hinsley et al., British Intelligence, 1: 326.
Page 56 ‘peculiarly incautious in their W/T chat’: ‘Report on the Work of 3G(N)’, 11 (PRO HW 3/121).
Page 57 six or seven pairs: ibid., 81.
Page 58 Heer cipher discipline: Friedman, ‘Report on E Operations’, 38–9.
Page 59 Babbage … was worried: ibid., 40.
Page 60 1,400 intercepts: ‘”E” situation 20th June 1942’, Tables I, IV (PRO WO 208/5028). This figure excludes the Green traffic. Since Green was essentially unbreakable. Hut 6 found that its inclusion in the intercept figures gave a misleading picture.
Page 61 between 3,300 and 6,000: Friedman, ‘Report on E Operations’, 4, 7, 4.
Page 62 five main sections: on the organization of Hut 6, see ibid., passim.
Page 63 two-thirds of the messages: ibid., 68.
Page 64 processed ‘duds’: ibid., 66.
Page 65 1,125 per day: Hut 6 Report, week ending 7 October 1944, in Fried Report #103 (NACP HCC Box 880, Nr. 2612).
Page 66 ‘the best that we can do’: ibid.
Page 67 ‘were ever likely to help’: ‘History of Military Sigint’, 76 (PRO HW 3/92).
Page 68 ‘deeply suspicious’: ibid.
Page 69 ‘Fusion Room’: ibid., 34.
Page 70 ‘is not a pretty one’: ‘De Grey’s History of Air Sigint’, 116.
Page 71 Denniston informed Blandy and Butler: ibid.
Page 72 ‘an act of grace’: ibid., 134.
Page 73 prevent Enigma coverage being transferred: minute, 26 August 1940, by Hut 6 cryptanalysts (PRO HW 14/6).
Page 74 ‘My only comment…’: ‘History of Air Sigint’, 135.
Page 75 ‘… lamentable and inexcusable’: ‘Notes on a Most Secret Document’, 9 September 1941 (PRO HW 14/19).
Page 76 ‘astonishingly and lamentably slow’: ‘History of Military Sigint’, 198 (PRO HW 3/92); ‘not then functioning well’: ‘History of Air Sigint’, 118.
Page 77 190 sets were needed: minutes of ‘E’ Sub-Committee Meeting, 7 August 1941 (PRO WO 208/5125).
Page 78 Army, RAF and Foreign Office sets: ‘Distribution of Sets Allocated to Interception of “E” Traffic’, 2 November 1941 (PRO HW 14/22).
Page 79 with thirty-six sets: ‘History of Military Sigint’, 205.
Page 80 Chiefs of Staff authorized: ibid., 210–11.
Page 81 increased from 210: ibid., 214A.
Page 82 64 per cent: ibid.
Page 83 second Y expansion: ibid., 216. The memorandum to the Chiefs of Staff is set out in AZ 244 (PRO WO 208/5026).
Page 84 105 sets: Friedman, ‘Report on E Operations’, 17.
Page 85 ‘as short of sets as ever’: J. Coleman, minute, 15 January 1945 (PRO HW 14/120).
Page 86 unable to break Yellow: minute, 26 August 1940, by Hut 6 cryptanalysts, 5 (PRO HW 14/6).
Page 87 sometimes even six: ‘The History of WO “Y” Group’, 48 (PRO HW 41/119).
Page 88 first-rate operators: ‘Appreciation of the “E” Situation, June to December 1942’, 7 (PRO HW 3/164).
Page 89 a burst of Morse: Barbara Littlejohn, ‘Eavesdropping on the Enemy’, in Hugh Skillen (ed.), The Enigma Symposium 1994 (privately printed. Pinner, 1994).
Page 90 sixty-eight sets: ‘Interception of Discriminant Groups in England’, 20 July 1941 (PRO HW 14/17).
Page 91 35 per cent: ‘Distribution of Sets Allocated to Interception of “
E” Traffic’ (PRO HW 14/22).
Page 92 380 Teile: ‘Appreciation of the “E” Situation, June to December 1942’, Table III (PRO HW 3/164).
Page 93 an invaluable source: Hinsley et al., British Intelligence, 2: 69, 374.
Page 94 Luftwaffe ‘Light Blue’ cipher: Hinsley et al., British Intelligence 1: 391.
Page 95 The only other Luftwaffe cipher: Hinsley et al., British Intelligence 2: 69.
Page 96 Luftwaffe key-lists except Brown: ‘Appreciation of the “E” Situation, June to December 1942’, 8.
Page 97 April Foxglove keys: ibid.
Page 98 were briefly revived: ‘Cryptanalytic Report on the Yellow Machine’, 81; cf. ‘Report on E Operations’, 46.
Page 99 140 and 290 decrypts: ‘Appreciation of the “E” Situation, June to December 1942’, 22, Table IV.
Page 100 prolific Red: Hinsley et al., British Intelligence, 2: 375.
Page 101 complete key repeats: ‘Appreciation of the “E” Situation, June to December 1942’, 22, Table IV (cf. 11); employed by Luftwaffe close support units: Hinsley et al., British Intelligence, 2: 375.
Page 102 used on the Russian front: ibid., 2: 294.
Page 103 broke no Vulture keys: ‘Huts 6 and 8: Summary for August and September 1941’, 4 October 1941 (PRO HW 14/20).
Page 104 Vulture and Chaffinch: ‘Graphs Illustrating the Work of Hut 6 from September 1941 to November 1942’ (PRO HW 3/164).
Page 105 broke Chaffinch: ‘Huts 6 and 8: Summary for August and September 1941’.
Page 106 part of October: Hinsley et al., British Intelligence, 2: 294.
Page 107 2,800 Heer signals: ‘”E” situation 20th June 1942’, Table [V.
Page 108 Even Heer Mediterranean ciphers: ‘Appreciation of the “E” Situation, June to December 1942’, 15.
Page 109 the Mediterranean Heer keys: ibid., 13.
Page 110 only Heer cipher to produce cillies: ibid., 5.
Page 111 success rate in 1942: the figures are from ‘Graphs Illustrating the Work of Hut 6’ and ‘”E” situation 20th June 1942’, Table IV.
Page 112 eight or more ciphers: ‘Graphs Illustrating the Work of Hut 6’, note on Graph 6.
Page 113 increased from 32,000; Unidentified traffic: ‘Graphs illustrating the work of Hut 6’.
Page 114 first five Stecker pairs; sent by land line: ‘Cryptanalytic Report on the Yellow Machine’, 82.
Page 115 solved the Railway traffic: letter, 17 August 1940, to Col. Hatton-Hall (PRO HW 14/6); ‘GCCS Report for 1940. German section No 4. Intelligence School’ (PRO HW 14/11); Hinsley et al., British Intelligence, 2: 668. For the decrypts, see GRD 1–59 (PRO HW 5/745).
Page 116 90 per cent success rate: ‘Graphs illustrating the work of Hut 6’.
Page 117 stopped using discriminants: Ultra/Zip CCR 22, 27 February 1944, ‘German Signals Security Improvements Since the Battle of El Alamein (October/November) 1942’, 2 (NACP RG 38, Radio Intelligence Publications, Box 169, RIP 403).
Page 118 identified many of the Heer’s ciphers: Hinsley et al., British Intelligence, 3(2):779.
Page 119 UKD would be widely used: S. Milner-Barry, memorandum, 25 July 1944, ‘Operation D’ (PRO HW 14/101).
Page 120 about twenty-five Luftwaffe ciphers: Hinsley et al., British Intelligence, 3(2): 847.
Page 121 enciphered call signs: Ultra/Zip CCR 38, 22 December 1944, ‘German Signals Security Improvements During 1944’, 2, 6 (RIP 403).
Page 122 retained their fixed frequencies: The History of WO “Y” Group’, 67.
Page 123 Figure 4.3, Enigma breaks (Hut 6) 1942 and 1944: ‘”E” situation 20th June 1942’, Tables I, IV; ‘Appreciation of the “E” Situation, June to December 1942’; IR 4082, Annex E, ‘Figures for November’ (‘Capt. Walter J. Fried Reports’, NACP HCC, Box 880, Nr. 2612).
Page 124 a system under which: ‘History of German Air Section’, Section V of Part I: 11 (PRO HW 3/106); cf. Hinsley et al., British Intelligence, 3(2):848 (referring only to ‘improved security precautions’ then, even though the nature of the precautions had been published in 1986).
Page 125 fell from 1,800 to 1,000 daily: ibid.
Page 126 a postwar history concluded: ULTRA and the History of the United States Strategic Air Force in Europe vs. the German Air Force (University Publications of America, Frederick, MD, 1986 – a reprint of SRH 13), p. 179.
Page 127 special ‘traffic watch’: ‘History of German Air Section’, Section V of Part I, 12.
Page 128 thirteen occasions: Hinsley et al., British Intelligence, 2: 662.
CHAPTER 5 HUT 6 FROM THE IN SIDE
Derek Taunt has sadly passed away since writing this chapter. He died on 15 July 2004, aged 86. Obituaries: The Daily Telegraph, 23 July 2004; The Times, 13 August 2004
http://www.timesonline.co.uk/tol/comment/obituaries/article468838.ece
http://www.telegraph.co.uk/news/obituaries/1467625/Derek-Taunt.html
Page 1 ‘an exaggerated view of security …’; ‘… not at first satisfactory’: ‘De Grey’s History of Air Sigint’, 135 (PRO HW 3/95).
Page 2 main Luftwaffe cipher had just been broken: ‘The History of WO “Y” Group’, 48 (PRO HW 41/119).
Page 3 Milner-Barry on the 6813th Signal Security Detachment: Milner-Barry, letter 10 May 1945, to William Bundy, ‘Technical History of the 6813th Signal Security Detachment’, 13 (NACP HCC Nr. 4685).
Page 4 Welchman on the management of Hut 6: Gordon Welchman, The Hut Six Story: Breaking the Enigma Codes (Allen Lane, London, 1982), pp. 126–7.
Page 5 Milner-Barry on Welchman: ‘In Memoriam W. Gordon Welchman’, Intelligence and National Security, 2(1) (1986), 141.
Page 6 ‘hankies’: these were charts (sometimes called ‘hanky-pankies’) in which a ‘discriminatrix’ recorded cipher discriminants, plus the name of the ciphers and the radio frequencies used. The name was derived from John Hancock, who designed the chart.
CAPTER 6 BREAKING ITALIAN NAVAL ENIGMA
Page 1 rang through to Bletchley Park: letter from Edward Clarke, Nobby’s son, who was on duty when the message came through.
Page 2 He suspected dactyls and a rhyme: Penelope Fitzgerald, The Knox Brothers (London, Macmillan, 1977), pp. 145–6.
Page 3 Alice in ID25: CCAC MSS DENN 3/3.
Page 4 The story of the Polish contribution: see Chapter 4.
Page 5 ‘… not mathematical but classical’: Christopher Andrew, Secret Service: The Making of the British Intelligence Community (William Heinemann, London, 1985), p. 96.
Page 6 ‘very strange beasts indeed …’: Michael Smith, Station X: The Codebreakers of Bletchley Park (Channel 4 Books, London, 1998), p. 16.
Page 7 ‘Knox grasped everything very quickly: Wladyslaw Kozaczuk, Enigma (University Publications of America, Frederick, MD; Arms and Armour Press, London, 1984), pp. 60, 236.
Page 8 He enclosed a set of rods: ibid., p. 60.
Page 9 Welchman, who had given much thought to the necessary organizational methods: see Gordon Welchman, The Hut Six Story: Breaking the Enigma Codes (Allen Lane, London, 1982), pp. 74–6.
Page 10 Denniston recalled later: Denniston, letter to Knox, 11 November 1941 (PRO HW 14/22).
Page 11 ‘treatise on the Enigma’: ‘Mathematical theory of ENIGMA machine by A. M. Turing’, also known as Turing’s ‘Treatise on the Enigma’ (PRO HW 25/3). Turing’s example of rodding is from the unsteckered Railway Enigma. Its wiring was solved by Hut 8 in 1940, using established methods (see p. 61).
Page 12 ‘the work did not really need mathematics’: F. H. Hinsley and Alan Stripp (eds), Codebreakers: The Inside Story of Bletchley Park (OUP, Oxford, 1993), p. 113.
Page 13 Cunningham came down: John Winton, Cunningham (John Murray, London, 1998), p. 139.
Page 14 ready with a poem: personal possession.
Page 15 Ultra Secret: E W. Winterbotham, The Ultra Secret (Weidenfeld & Nicolson, London, 1974), p. 66.
Page 16 accompanying book: Richard Deacon and Nigel West, Spy! (BB
C, London, 1980), pp. 76–7.
Page 17 The Times, 18 February 1980.
CHAPTER 7 A BIOGRAPHICAL FRAGMENT: 1942–5
Page 1 Many of the signals translated: decrypts of the Coral signals are in PRO ADM 223/264–83, as the SJA series, and at NACP as RG 457, SRNA series. Translations of Japanese Naval Attaché messages.
CHAPTER 8 AN UNDERVALUED EFFORT: HOW THE BRITISH BROKE JAPAN’S CODES
Page 1 Hobart-Hampden success: A. G. Denniston, ‘GC&CS Between the Wars’, Intelligence and National Security, 1(1) (1986), 55–6.
Page 2 Difficulties with Japanese interception: Jones to Lambert, 22 August 1924 (PRO HW 3/1), Folio 15; W. F. Clarke, ‘Documents Relating to Naval Section’ (PRO HW 3/1), Folio 1. 4–5; W. R Clarke, ‘History of Naval Section, The Years Between’ (PRO HW 3/16), 5, 20, 21.
Page 3 Problems finding Naval Japanese experts: ‘GCCS Requests Treasury Approval for Four new junior Assistant posts for new Sigint Bureau Proposed for Hong Kong’ (PRO HW 3/55).
Page 4 Nave on recruitment by Royal Navy and Admiralty instructions: Eric Nave, ‘An Australian’s Unique Naval Career’ (unpublished memoir, Australian War Memorial, MSS 1183), pp. 168–79. NB. This appears to be the first record of the use of ‘Y’ for interception.
Page 5 Nave progress and Flintham: Nave, ‘An Australian’s Unique Naval Career’, pp. 168–200; Nave Notes on Procedure Y, 30 March 1926 (Australian National Archives Melbourne, MP 1049, 1997/5/196).
Page 6 Improvement in Japanese codes and ciphers: Michael Smith, The Emperor’s Codes: Bletchley Park and the Breaking of Japan’s Secret Ciphers (Dialogue, London, 2010), p. 34.
Page 7 Tiltman on breaking Japanese military attaché system: J. H. Tiltman, ‘Some Reminiscences’ (NACP HCC Nr. 4632), 5.
Page 8 Foss and Strachey break the Japanese naval attachés’ machine cipher: Nave, ‘An Australian’s Unique Naval Career’, pp. 338–45. NB. This was the machine referred to by the US Navy codebreakers as Orange and broken by them in February 1936, apparently as a result of a ‘pinch’ of information, possibly even a machine, from the apartment of the Japanese naval attaché in Washington. See L. F. Safford, ‘History of Japanese Cipher Machines’, 3 February 1944 (NACP HCC Nr. 2344), 1–2.
The Bletchley Park Codebreakers Page 51