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 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