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Index
National Archives Note
Editor's Note
Original Editor's Preface
The Plan of the Book
Hut 6: An Adventure [Overview of Hut 6 by Stuart Milner-Barry]
Appreciation of Milner-Barry
The German Enigma Machine
Chapter 1: PRE-WAR THEORY
Introductory
Pre-War: Early Theory
The first crib
Rods and wheel-breaking
The Indicating System and its vulnerability
Depth and turnover
New wheels and Indicating System: the goal-hunt
News from Poland
Polish methods of key-breaking
Chapter 2: War: the first successes
The outbreak of war
The Bombe and the Netz
The Jeffreys Sheets
Method of using the Netz
Early failures
Cillies and attempts at depth-reading
First breaks of war-time keys
Chapter 3: January-March 1940
Red, Blue and Green
Success and early organisation
Operational Breaking
Rise of Yellow
The new Indicating System: first great crisis of Hut 6
Overwhelming importance of Red
Hand breaks
Chapter 4: Rules of Keys
General considerations
The rules of Red
Results of the discoveries
Rules of other keys
Red keys: June 1940
Daily Procedure in Machine Room
Liaison with France
Chapter 5: Rise of Bombes and the Crib Room
General historical summary
Arrival of the Bombe: What it did
Establishment of the Crib Room
New Discoveries on Rules of Keys: Brown
Origins of Research
Function of Research
Early organisation and methods
Early triumphs
Summary
Chapter 6: General Historical Summary
Features of the period
Increase of keys
Increase of personnel
Increase of machines
Growing complexity of organisation
Technical developments
General course of breaking
Liaison with Sixta
Liaison with Hut 3
Conclusion
Chapter 7: Detailed Theory of Rules of Keys
Sources of information
Air and Army
Divisions of the subject
Wheelorder rules: Army and Air
Clarkian wheelorder rule
Nigelian wheelorder rule
Monrovian wheelorder rule
Tricycle keys
Setting up of Committee on Rules of Keys
Ringstellung Rules – Army and Air
Army ringstellung rules
Air ringstellung rules
Stuttering ringstellung
Stecker Rules – Army and Air
Air rules and tendencies
Army rules in general and particular
Brown Rules
GAF Key Repeats
Institution of key records
Limitation of the subject
Local keys
Keys constructed by the Cipher Office: repeats in 1941
1942 – Quadrilateral repeats
Effects on breaking policy
Effects on intercept policy
Repeats in 1943 and 1944
Stecker/D repeats in 1945
Conclusion
Chapter 8: General Organisation of Machine and Crib Rooms (Later Watch and Research)
The fourfold division
Location of rooms
Sub-ordination of sub-sections
Differentiation of function
Dissatisfaction in Machine Room
Problem solved
Formation of Research
Parentage system
Some special points
Summary
Chapter 9: Training Schemes in Hut 6
Early Training
Beginning of the schools
The RR School syllabus
Watch and Research training
The outline course and special talks
Other educational schemes
Chapter 10: General Historical Summary
The determining factors
The technique of cryptography
The organisation of cryptography
Importance of other sections to cryptography
Contribution of Hut 6 to Intelligence
Chapter 11: German Security Devices - 1 Reflector D (Part 1)
General Introduction
Reflector D in general
January to July 1944
The first menace
Illusory triumph
The BO mystery
STECKERVERBINDUNGEN AN DEN UMKEHRWALZE
D Substitution
Greenshank and D
Red Ds: January to July
The overhanging menace
Preparations for 1 August
Chapter 12: German Security Devices - 2 Reflector D (Part 2)
Extension of D
Effects on breaking
D-breaks
D captures
D Rules
Summary of the German use of D
Chapter 13: German Security Devices - 3
The problem
Routine adopted
Extension of Enigma Uhr
Effect on breaking
Uhr notation
Summary
Zusatz Stecker
The May scare
A damp squib
Extent of change
The German idea
NOT-Schlüssel
Introduction
First system
First appearance of the NOTS
Guernsey saga or the Qwatch and the Forty NOTS
The plague of NOTS
New-style NOT-keys
Conclusions
Chapter 14: German Security Devices - 4
Introduction:
Extension of the practice
The German regulations
RESETTING WHEELS WITHIN MESSAGES
Effect on breaking
Conclusion
Random Indicators: The Regulations
CHOICE AND USE OF THE INDICATOR (SPRUCHSCHLÜSSEL)
Extension of the system
Conclusion
Wahlworts
Introduction
Extension of wahlworts
German use of wahlworts
Effect on breaking
Value of wahlworts
The Mosse Code
Double encoding
Summary
Chapter 15: Change from Watch/Research to Air/Army
Introduction
Stages of the change
Reasons for the change
Results of the change
Timing of the change
Unity of control
Organisation of the Watch
Introduction
Function of the Watch
Basic organisation
Division of keys between Watches
Watch A (three shifts)
Watch Q
Administration
Chapter 16: Final Developments of the Rules of Keys
Introduction
Regular Air keys
Army keys
Summary
Chapter 17: Bombe Control
Introduction
The problem
"Intelligence Value"
Hut 6 – Hut 8
Hut 6 keys
Responsibility
Daily meeting
Priority list
Current bombe control
England
Washington (Op-20-G)
Washington (Arlington)
Conclusion
Chapter 18: History of the Machine Room (formerly Netz Room)
Historical Outline
Expansion of the Room
The breaking of duds
Final set-up for bombe control
Communications
Routine organisational jobs
Normal testing of stops
Special problems
Chapter 19: Red, Blue, Pink and Brown Keys
General Introduction
Red
Red: A major Army blunder
Breaking — 1940 to 1945
Supreme importance of Red
Blue and Pink
Brown
Introduction
"Target for Tonight" Phase I: September 1940-May 1941
"Target for Tonight" Phase II: December 1941-June 1942 Brown II
The lull: Brown I
Attack and Defence
Conclusion
Example of Depth in Brown I
Chapter 20: The Mediterranean Air Keys
General
The Triangle
The African campaign
The Italian campaign
The Balkans
The last months
Chapter 21: The African Army Keys
General
The first breaks: 1941-1942
The re-entry into Chaffinch: April 1942
April-October: improvement in technique and increasing success
Phoenix: the difficulties of overseas interception
The wahlwort era – the Phoenix-Finch complex: December 1942-April 1943
Thrush (Sonder M/S Rom-Mallemes) and other keys
Chapter 22: The Italian Army and Balkan Army Keys
Italian Army Keys
General
Before the surrender of Italy: May-September 1943
Surrender of Italy and rise of Shrike and Bullfinch:
September 1943-February 1944
Kingfisher: May-August 1944
Revival of Albatross: October 1944-April 1945
The Puffins
Sparrow
The Balkan Army Keys
General
Before the Italian surrender: February 1942-September 1943
Surrender of Italy: appearance of Wryneck:
September 1943-November 1944
Arrival of Russians and new Balkan set-up: November 1944
Chapter 23: The Western Air and Army Keys
Western Air Keys
General
The breaking of Snowdrop
The pivotal importance of Red
The further growth of the re-encodement complex
D-Day
The period of regular breaking
Changes in emphasis
The decline of the West
Western Army Keys
General
Before D-Day
D-Day and the first breaks
The first lull
The breakthrough
The second lull: October
The final battles: heavy traffic once again
Chapter 24: German Air and Eastern Air Keys
German Air Keys
General
Research
The Watch
The first phase
The second phase
The third phase
The Eastern Air Keys
General
The German advance
Key repeats
Hedgehog
The heyday of Research
The problem of the Luftflotten
The end
Chapter 25: The Eastern Army Keys Greenshank and Allied Keys
The Eastern Army Keys
General
Initial advances: June-December 1941
Quiescence: 1942-1943
Spread of use of local keys: July 1943 – December 1944
The final spurt
Greenshank and Allied keys:
The main feature of Greenshank
Breaks: 1939-1942
A blank wall
Inside information
The mystery solved
The last phase: statistics and summary
The associated keys: Falcon, Gannet II and Mallard
The breaking of Nuthatch
Grouse and the Wehrkreis CQ key
The role of WOYG (War Office Y Group)
Chapter 26: Police and SS Keys
General Characteristics
History to the end of 1941
1942: The Orange Age
1943-1945: The Quince Age
Summary
Chapter 27: Mustard
Introduction
Russian Mustard: Mustard I, IV
Mediterranean Mustard: Mustard II, III
Western Mustard and Cress
The end of the story
Chapter 28: The V-Keys
General Introduction
Corncrake
Ibis
Jerboa
Importance of the V-keys
Chapter 29: Summary and Conclusions
General
How breaks are secured
How breaks can be prevented
The three desiderata
The two roads
The principle of over-protection
The German Enigma
Theoretical and practical security
The failure of German efforts
Air and Army security
The special case of Greenshank
How to achieve security
The Necessity of Supervision
NOTE TO THE APPENDICES ON KEYS: ENGLISH KEY NAMES OF AIR AND ARMY KEYS
Note to Appendix I: First Break of Keys
APPENDIX I:: FIRST BREAK OF KEYS
NOTE TO APPENDICES II - IV: GENERAL USE AND DISTRIBUTION OF GAF KEYS
APPENDIX II: LIST OF GERMAN CATEGORIES OF GAF KEYS
APPENDIX III: ALPHABETICAL LIST UNDER ENGLISH NAME OF ALL GAF KEYS
APPENDIX IV: LIST OF COUNTY KEYS
NOTES TO APPENDICES V and VI: GENERAL USE AND DISTRIBUTION OF ARMY KEYS
APPENDIX V: THE VARIOUS CATEGORIES OF GERMAN ARMY KEYS OPERATIVE IN MARCH 1945
APPENDIX VI: LIST OF ALL GERMAN ARMY KEYS IDENTIFIED DURING THE WAR
GLOSSARY
INDEX
FIND OUT MORE
About the Author
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