Breaking Teleprinter Ciphers at Bletchley Park An edition of I.J. Good, D. Michie and G. Timms: General Report on Tunny with Emphasis on Statistical Methods (1945)

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 xiii

Editorial Notes xiv

Notes on Vocabulary xiv

List of Abbreviations xv

Cryptanalytic Significance of the Analysis of Tunny, by Whitfield Diffie xvii

Editors’ Introduction, by Whitfield Diffie and J. V. Field xxv

Statistics at Bletchley Park, by S. L. Zabell lxxv

Biographies of Authors ciii

Notes on the Editors of the Present Volume cvii

List of Figures cix

General Report on Tunny, with emphasis on statistical methods 1

Part 0: Preface

Chapter 01: Preface 3

Part 1: Introduction

Chapter 11: German Tunny 6

Chapter 12: Cryptographic Aspects 22

Chapter 13: Machines 32

Chapter 14: Organisation 35

Chapter 15: Some Historical Notes 39

Part 2: Methods of Solution

Chapter 21: Some Probability Techniques 43

Chapter 22: Statistical Foundations 50

Chapter 23: Machine Setting 80

Chapter 24: Rectangling 110

Chapter 25: Chi-Breaking from Cipher 139

Chapter 26: Wheel-Breaking from Key 185

Chapter 27: Cribs 219

Chapter 28: Language Methods 237

Part 3: Organisation

Chapter 31: Mr Newman’s Section 262

Chapter 32: Organisation of the Testery 267

Chapter 33: Knockholt 268

Chapter 34: Registration and Circulation 269

Chapter 35: Tapemaking and Checking 271

Chapter 36: Chi-Breaking from Cipher 275

Chapter 37: Machine Setting Organisation 277

Chapter 38: Wheel-Breaking from Key, Organisation 280

Chapter 39: Language Methods 282

Part 4: Early Methods and History

Chapter 41: The First Break 284

Chapter 42: Early Hand Methods 290

Chapter 43: Testery Methods 1942–44 298

Chapter 44: Hand Statistical Methods 305

Part 5: Machines

Chapter 51: Introductory 309

Chapter 52: Development of Robinson and Colossus 312

Chapter 53: Colossus 316

Chapter 54: Robinson 336

Chapter 55: Specialized Counting Machines 346

Chapter 56: Copying Machines 350

Chapter 57: Simple machines 361

Chapter 58: Photographs 362

Part 6: Raw Materials

Chapter 61: Raw Materials — Production, with Plans of Tunny Links 381

Part 7: References

Chapter 71: Glossary and Index 387

Chapter 72: Notation 435

Chapter 73: Bibliography 441

Chapter 74: Chronology 444

Part 8: Conclusions

Chapter 81: Conclusions 452

Part 9: Appendices

Chapter 91: The 5202 Machine 456

Chapter 92: Recovery of Motor Patterns from De-chi 471

Chapter 93: Thrasher 482

Chapter 94: Research into the QEP System 484

Chapter 95: Mechanical Flags 488

Appendix A: Transmission of Teleprinter Signals, by J. A. Reeds 495

Appendix B: Activities at Knockholt, by J. A. Reeds 503

Appendix C: The 5202 Machine, by J. A. Reeds 530

Appendix D: Initial Conception of Colossus, by J. A. Reeds 535

Appendix E: List of Scanned Exhibits 540

Supplementary Glossary 542

Biographical Notes 547

Notes 561

Bibliography 624

Index 645

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