Breaking Teleprinter Ciphers at Bletchley Park

James A. Reeds is an applied mathematician and is currently on the research staff at the Center for Communications Research, Princeton, NJ.Whitfield Diffie is best known for his 1975 discovery of the concept of public key cryptography. Since 1993, he has worked largely on public policy aspects of cryptography. His position in opposition to limitations on the business and personal use of cryptography has been the subject of articles in the New York Times and programs on networks such as CNN.J.V. Field, an Honorary Visiting Research Fellow in the Department of History of Art at Birkbeck, University of London, is now a historian of science but in the 1960s worked as a computer programmer.

• Preface xiiiEditorial Notes xivNotes on Vocabulary xivList of Abbreviations xvCryptanalytic Significance of the Analysis of Tunny, by Whitfield Diffie xviiEditors’ Introduction, by Whitfield Diffie and J. V. Field xxvStatistics at Bletchley Park, by S. L. Zabell lxxvBiographies of Authors ciiiNotes on the Editors of the Present Volume cviiList of Figures cixGeneral Report on Tunny, with emphasis on statistical methods 1Part 0: PrefaceChapter 01: Preface 3Part 1: IntroductionChapter 11: German Tunny 6Chapter 12: Cryptographic Aspects 22Chapter 13: Machines 32Chapter 14: Organisation 35Chapter 15: Some Historical Notes 39Part 2: Methods of SolutionChapter 21: Some Probability Techniques 43Chapter 22: Statistical Foundations 50Chapter 23: Machine Setting 80Chapter 24: Rectangling 110Chapter 25: Chi-Breaking from Cipher 139Chapter 26: Wheel-Breaking from Key 185Chapter 27: Cribs 219Chapter 28: Language Methods 237Part 3: OrganisationChapter 31: Mr Newman’s Section 262Chapter 32: Organisation of the Testery 267Chapter 33: Knockholt 268Chapter 34: Registration and Circulation 269Chapter 35: Tapemaking and Checking 271Chapter 36: Chi-Breaking from Cipher 275Chapter 37: Machine Setting Organisation 277Chapter 38: Wheel-Breaking from Key, Organisation 280Chapter 39: Language Methods 282Part 4: Early Methods and HistoryChapter 41: The First Break 284Chapter 42: Early Hand Methods 290Chapter 43: Testery Methods 1942–44 298Chapter 44: Hand Statistical Methods 305Part 5: MachinesChapter 51: Introductory 309Chapter 52: Development of Robinson and Colossus 312Chapter 53: Colossus 316Chapter 54: Robinson 336Chapter 55: Specialized Counting Machines 346Chapter 56: Copying Machines 350Chapter 57: Simple machines 361Chapter 58: Photographs 362Part 6: Raw MaterialsChapter 61: Raw Materials — Production, with Plans of Tunny Links 381Part 7: ReferencesChapter 71: Glossary and Index 387Chapter 72: Notation 435Chapter 73: Bibliography 441Chapter 74: Chronology 444Part 8: ConclusionsChapter 81: Conclusions 452Part 9: AppendicesChapter 91: The 5202 Machine 456Chapter 92: Recovery of Motor Patterns from De-chi 471Chapter 93: Thrasher 482Chapter 94: Research into the QEP System 484Chapter 95: Mechanical Flags 488Appendix A: Transmission of Teleprinter Signals, by J. A. Reeds 495Appendix B: Activities at Knockholt, by J. A. Reeds 503Appendix C: The 5202 Machine, by J. A. Reeds 530Appendix D: Initial Conception of Colossus, by J. A. Reeds 535Appendix E: List of Scanned Exhibits 540Supplementary Glossary 542Biographical Notes 547Notes 561Bibliography 624Index 645