The Bletchley Park Codebreakers (59 page)

Page
83
Origins of Station X: Michael Smith,
Station X: The Codebreakers of
Blettchley Park
(Channel 4 Books, London, 1998), p. 20.

Page
84
Number of codebreakers: ‘Personnel at BP’ (PRO HW 3/82).

Page
85
Co-operation with French expanded: Expansion of Anglo–French Cooperation in Naval Work – German, Russian and Italian. Item 10 dated 6 April 1940 (PRO HW 14/4).

Page
86
Russian section at Wavendon: ‘Russian Naval Section at Wavendon (Combined Section)’, handwritten notes (PRO HW 3/151).

Page
87
Russian section at Sarafand: Denniston Minute, Item 35, dated 26 April 1940 (PRO HW 14/4).

Page
88
High-grade military cipher broken during Finnish–Russian War: Russian Section Report on Work for 1940 (PRO HW 14/11); Denniston Minute, Item 35, dated 26 April 1940 (PRO HW 14/4). These breaks were to be the last into any high-grade Russian armed forces traffic for at least another decade. See Benson and Phillips,
History of Venona
1:29.

Page
89
Tiltman foresight in arranging deal with Finns: Denniston to Menzies dated 29 April 1940, Item 47 (PRO HW 14/4).

Page
90
Tiltman’s role in breaking Japanese super-enciphered codes and JN-25 in particular: see Michael Smith,
The Emperor’s Codes: Bletchley Park and the Breaking of Japan’s Secret Ciphers
(Dialogue, London, 2010), pp. 54–60.

Page
91
Details of exchange deal and subsequent difficulties: Tiltman résumé of information obtained during recent tour of Finland, 10 April 1940, Item CC/27 (PRO HW 14/4).

Page
92
Finns provided an increased flow of Russian military and KGB traffic and two Russian Army codebooks: ‘Narrative of Liaison between British and Finnish General Staffs on the subject of cryptography and Wireless Interception’, 16 April 1940, Item 27 (PRO HW 14/4); Denniston to Menzies, 29 April 1940, Item 47 (PRO HW 14/4); Denniston to Menzies 7 July 1940, Item 12 (PRO HW 14/6); Tiltman to CSS 30 May 1941, Item 82 (PRO HW 14/15).

Page
93
Finns’ supply of codebooks: Godfrey to Tiltman, 2 September 1940. Report on the letterwriter’s liaison visit to the Finns, Item 4 (PRO HW 14/7); Russian Section Report on Work for 1940 (PRO HW 14/11). Since Godfrey appears to indicate these were full codebooks, they must have been ‘pinches’, i.e. captured codebooks. Finns’ supply of military and KGB (NKVD) traffic: Benson and Phillips,
History of Venona
,1:29.

Page
94
Stockholm receivers: ‘Russian Naval Pre-War, 1924–1939’ (PRO HW 3/151), 2.

Page
95
Flowerdown and Scarborough: second page of handwritten notes on ‘Russian Naval’ (ibid.).

Page
96
Vlasto sent to Sarafand: two trained cryptographers for Middle East, 28 May 1940, Item 31 (PRO HW 14/5).

Page
97
India, Sarafand and RAF experiment on Caucasus traffic: Wavell Report on Item 2 of the Agenda for the India Middle East Intelligence Conference held at Cairo, 3–8 April 1940, dated 9 April 1940, Item 38/5/1 (PRO HW 14/4).

Page
98
RAF in Cairo, minute 18 April 1940, Item 8a (PRO HW 14/5).

Page
99
Dingli and Ismailia: extract from CinC Mediterranean Most Secret Letter, 27 April 1940, Item 39 (PRO HW 14/4).

Page
100
Alexandria: Naval Y Service Proposed Expansion, Item 65 (PRO HW 14/6).

Page
101
FECB watch on Vladivostok and Kiel: second page of handwritten notes on ‘Russian Naval’, entry marked ‘GCCS papers’, 10 March 1940.

Page
102
Australian and New Zealand codebreakers: Papers on Visit of Captain
F. J. Wylie to Australia and New Zealand (National Australian Archives (Melbourne)) MP1185 2021/5/529, 82–4.

Page
103
French codebreakers: ‘Russian Naval Pre-War, 1924–1939’, 4.

Page
104
Polish operators and codebreakers: Denniston to Menzies. Ref. No. 2572, 5 October 1940, Item 12 (PRO HW 14/7). It is interesting to note, given the minor degree of controversy surrounding the decision that the Poles should concentrate on Russian material, that both these references appear to indicate that it was they who first suggested it.

Page
105
Interception of traffic in Ukraine: Capt. A. C. Stuart Smith to Tiltman, 7 January 1941, Item 17 (PRO HW 14/10).

Page
106
Denniston on importance of Finnish liaison: Denniston to Menzies, 14 January 1941, Item 46 (PRO HW 14/10).

Page
107
Concern over increasing collaboration between the Finnish General Staff and the Germans: letter to General Tadeusz Klimecki re W/T Operators for Soviet military and air interception. Dated 6 June 1941, Item 18 (PRO HW 14/16).

Page
108
Poles asked to reinforce their operation: ibid.

Page
109
Tiltman query: Tiltman to Helsinki MI6 Head of Station, 16 June 1941, item 58 (PRO HW 14/16).

Page
110
According to popular mythology: F. H. Hinsley et al.,
British Intelligence
in the Second World War
(HMSO, London, 1979), 1:199. The discretion of the official historian of British wartime intelligence was again in evidence when he stated inaccurately but perhaps at the request of GCHQ that ‘All work on Russian codes and ciphers was stopped from 22 June 1941, the day on which Germany attacked Russia.’

Page
111
Debate over when to stop Russian work: War Diary No. 5 Intelligence School, entry for 28 June 1941 (PRO WO 169/2578); CinC Med to Admiralty, 10 September 1941, Item 42 (PRO HW 14/19); CinC India to War Office, 9 September 1941, Item 46 (PRO HW 14/19); Denniston memo, 30 September 1941, Item 153 (PRO HW 14/19); minute dated 2 October 1941 (PRO HW 14/20); CinC India to WO, 9 September 1941, Item 46 (PRO HW 14/19); War Diary No. 5 Intelligence School, entry for 28 August 1941 (PRO WO 169/2578).

Page
112
Poles asked to continue covering Russian material and watch kept by British sites on known frequencies: Denniston memo, 30 September 1941 (PRO HW 14/19).

Page
113
Resurgence of Soviet illicit traffic: Benson and Phillips,
History of Venona
1:30; Jefferson, Petrie-Menzies meeting, and ‘Bundles of Russian traffic’:
The Security Service 1908–1945
, pp. 358–9.

Page
114
Russian coverage refined: Benson and Phillips,
History of Venona
1:30–1.

Page
115
GC&CS secret Russian section: John Croft, ‘Reminiscences of GCHQ and GCB, 1942–45’,
Intelligence and National Security
, 13(4) (1998), 138–9.

Ralph Erskine would like to thank Philip Marks, Geoff Sullivan, the late Derek Taunt and Frode Weierud for their comments on Chapter 4.

Page
1
Hut 6’s successes: for a comprehensive account of Hut 6’s work, see ‘The History of Hut 6, Volumes I to III’ (PRO HW 43/70–2).

Page
2
‘was won, in a very large measure…’: ‘The History of WO “Y” Group’, 109 (PRO HW 41/119).

Page
3
Navy adopted two simple versions: minute, 15 September 1926 (PRO HW 25/6).

Page
4
‘Practical knowledge of [
Wehrmacht
] enigma nil’: [D. Knox?], minute, 13 January 1939 (PRO HW 25/12).

Page
5
Figure 4.1: based on a figure in A. Ray Miller,
The Cryptographic
Mathematics of Enigma
(NSA, Fort Meade).

Page
6
‘a stony silence’, etc.: A. G. Denniston [nd], ‘How News was brought from Warsaw at the end of July 1939’ (PRO HW 25/12); Ralph Erskine, ‘The Poles Reveal their Secrets: Alastair Denniston’s Account of the July 1939 Meeting at Pyry’,
Cryptologia
, 30 (2006), 294.

Page
7
‘Mrs B.B.’… ‘had seriously contemplated’: Knox to Denniston, letter [nd, but c. late July 1939, or early August, on Hotel Bristol, Warsaw, note-paper] (PRO HW 25/12).

Page
8
actual punching: A. D. Knox, and others, memorandum, 1 November 1939 (PRO HW 14/2).

Page
9
one third of the time predicted: ibid.

Page
10
contravene Denniston’s orders: Knox, memorandum, 3 December 1939 (PRO HW 25/12).

Page
11
could not solve any Enigma: F. H. Hinsley et al.,
British Intelligence in the
Second World War: Its Influence on Strategy and Operations
(HMSO, London, 1988), 3(2):952.

Page
12
rotors IV and V had been incorrect: ‘De Grey’s History of Air Sigint’, 95 (PRO HW 3/95).

Page
13
Denniston asked Menzies: Denniston, letter, 9 January 1940 (PRO HW 14/3).

Page
14
Menzies duly wrote: Menzies, letter, 10 January 1940 (ibid.).

Page
15
on 28 December 1939: Note from X to Y, 28 December 1939 (PRO HW 25/12).

Page
16
Jeffreys sheets: ‘Mathematical theory of ENIGMA machine by A. M. Turing’, 95 (PRO HW 25/3). Gordon Welchman,
The Hut Six Story: Breaking
the Enigma Codes
(Allen Lane, London, 1982), pp. 71–2, errs in describing these sheets as being the same as the Zygalski perforated sheets. However, John
Jeffreys was also working on a British version of the Zygalski sheets.

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.