Code Breaking in the Pacific

1. Front Matter

   Pages i-xxvi

   PDF

2. Build Up

   1. Front Matter

      Pages 1-1

      PDF

   2. Communications and Sigint

      • Peter Donovan, John Mack

      Pages 3-28

   3. Japanese Expansion 1895–1941

      • Peter Donovan, John Mack

      Pages 29-34

   4. The GCCS 1919–1941

      • Peter Donovan, John Mack

      Pages 35-47

   5. William Friedman and the US Army

      • Peter Donovan, John Mack

      Pages 49-55

   6. Early American Naval Sigint

      • Peter Donovan, John Mack

      Pages 57-66

   7. Developments in Australia

      • Peter Donovan, John Mack

      Pages 67-78

   8. Preparedness for Attack?

      • Peter Donovan, John Mack

      Pages 79-91

3. Technical

   1. Front Matter

      Pages 93-93

      PDF

   2. Major Encryption Systems

      • Peter Donovan, John Mack

      Pages 95-120

   3. JN-25 and Its Cryptanalysis

      • Peter Donovan, John Mack

      Pages 121-159

   4. Using Common Book Groups

      • Peter Donovan, John Mack

      Pages 161-180

   5. Recovery of a Code Book

      • Peter Donovan, John Mack

      Pages 181-192

   6. Breaking Additive Systems

      • Peter Donovan, John Mack

      Pages 193-205

   7. Making Additive Systems Secure

      • Peter Donovan, John Mack

      Pages 207-225

   8. Redundant Encryption

      • Peter Donovan, John Mack

      Pages 227-246

   9. The Scanning Distribution

      • Peter Donovan, John Mack

      Pages 247-269

4. Ciphers and the Submarines

   1. Front Matter

      Pages 271-271

      PDF

   2. Ciphers and the Submarines

      • Peter Donovan, John Mack

      Pages 273-286

This book reveals the historical context and the evolution of the technically complex Allied Signals Intelligence (Sigint) activity against Japan from 1920 to 1945. It traces the all-important genesis and development of the cryptanalytic techniques used to break the main Japanese Navy code (JN-25) and the Japanese Army’s Water Transport Code during WWII. This is the first book to describe, explain and analyze the code breaking techniques developed and used to provide this intelligence, thus closing the sole remaining gap in the published accounts of the Pacific War. The authors also explore the organization of cryptographic teams and issues of security, censorship, and leaks. Correcting gaps in previous research, this book illustrates how Sigint remained crucial to Allied planning throughout the war. It helped direct the advance to the Philippines from New Guinea, the sea battles and the submarine onslaught on merchant shipping. Written by well-known authorities on the history of cryptography and mathematics, Code Breaking in the Pacific is designed for cryptologists, mathematicians and researchers working in communications security. Advanced-level students interested in cryptology, the history of the Pacific War, mathematics or the history of computing will also find this book a valuable resource.

• Breaking additive systems
• Censorship and leaks
• Ciphers
• Code breaking
• Crypanalysis
• Cryptology
• Damning
• Encryption systems
• Gap closing
• Redundant encryption

“It is an important contribution to both the history of the war and the history of cryptanalysis development, as well as an interesting text on techniques of cryptography and cryptanalysis. … The book is well written and reads well. It is well referenced with myriad footnotes. I admire and recommend it.” (Mordechai Ben-Menachem, Computing Reviews, April, 2015)

• School of Mathematics and Statistics, University of New South Wales, Sydney, Australia

  Peter Donovan

• School of Mathematics and Statistics, University of Sydney, Sydney, Australia

  John Mack

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