During the Second World War, Australia maintained a super-secret organisation, the Diplomatic (or `D’) Special Section, dedicated to breaking Japanese diplomatic codes. The Section has remained officially secret as successive Australian Governments have consistently refused to admit that Australia ever intercepted diplomatic communications, even in war-time. This book recounts the history of the Special Section and describes its code-breaking activities. It was a small but very select organisation, whose `technical’ members came from the worlds of Classics and Mathematics. It concentrated on lower-grade Japanese diplomatic codes and cyphers, such as J-19 (FUJI), LA and GEAM. However, towards the end of the war it also worked on some Soviet messages, evidently contributing to the effort to track down intelligence leakages from Australia to the Soviet Union.

"This is the story of the Allied codebreakers puzzling through the most difficult codebreaking problems that ever existed.

The award-winning New York Times bestseller about the American women who secretly served as codebreakers during World War II--a "prodigiously researched and engrossing" (New York Times) book that "shines a light on a hidden chapter of American history" (Denver Post). Recruited by the U.S. Army and Navy from small towns and elite colleges, more than ten thousand women served as codebreakers during World War II. While their brothers and boyfriends took up arms, these women moved to Washington and learned the meticulous work of code-breaking. Their efforts shortened the war, saved countless lives, and gave them access to careers previously denied to them. A strict vow of secrecy nearly erased their efforts from history; now, through dazzling research and interviews with surviving code girls, bestselling author Liza Mundy brings to life this riveting and vital story of American courage, service, and scientific accomplishment.

During the 1920s Herbert O. Yardley was chief of the first peacetime cryptanalytic organization in the United States, the ancestor of today's National Security Agency. Funded by the U.S. Army and the Department of State and working out of New York, his small and highly secret unit succeeded in breaking the diplomatic codes of several nations, including Japan. The decrypts played a critical role in U.S. diplomacy. Despite its extraordinary successes, the Black Chamber, as it came to known, was disbanded in 1929. President Hoover's new Secretary of State Henry L. Stimson refused to continue its funding with the now-famous comment, "Gentlemen do not read other people's mail." In 1931 a disappointed Yardley caused a sensation when he published this book and revealed to the world exactly what his agency had done with the secret and illegal cooperation of nearly the entire American cable industry. These revelations and Yardley's right to publish them set into motion a conflict that continues to this day: the right to freedom of expression versus national security. In addition to offering an exposé on post-World War I cryptology, the book is filled with exciting stories and personalities.

Beginning in the late 19th century, Imperial Japan embarked on a program of aggressive military overseas adventures in Asia and the Pacific. From 1904 to 1941, Japan's desire for resource independence had driven them to conquer Korea, Manchuria, large parts of China, and French Indochina, and to occupy large swaths of Pacific islands. These conquests provided tremendous resources, but still, they needed more. All these conquests were driven by the Samurai: the ancient warriors of Japan, answerable only to the needs for resources, an ill-defined bushido code, and their Emperor. They led Japan into a horrible war stretching across a third of the Earth's surface, knowing full well they could not defeat their enemies. Their plan was the uncertain hope that the West would falter and offer an olive branch, accepting Japanese hegemony in the Pacific and East Asia and granting them the resources they needed. This was a miscalculation driven by a folly of epic proportions. Four months of early and easy victories in 1941 convinced them of their invincibility. They refused to believe that their fighting spirit could be defeated by superior firepower and the sheer numbers of opponents. And the samurai had no Plan B.

Using previously unreleased documents, the author reveals new evidence that FDR knew the attack on Pearl Harbor was coming and did nothing to prevent it.

This book describes the impact of the American breaking of the Japanese codes and ciphers of WWII. The Japanese used both codes and ciphers for their messages.

The wartime secrets of the British codebreakers based at Bletchley Park continue to be revealed. In this book, Michael Smith examines how Japan's codes were broken, and the consequences of this for the Second World War.

To defeat your enemies you must know them well. In wartime, however, enemy codemakers make that task much more difficult. If you cannot break their codes and read their messages, you may discover too late the enemy's intentions. That's why codebreakers were considered such a crucial weapon during World War II. In Secret Messages, David Alvarez provides the first comprehensive analysis of the impact of decoded radio messages (signals intelligence) upon American foreign policy and strategy from 1930 to 1945. He presents the most complete account to date of the U.S. Army's top-secret Signal Intelligence Service (SIS): its creation, its struggles, its rapid wartime growth, and its contributions to the war effort. Alvarez reveals the inner workings of the SIS (precursor of today's NSA) and the codebreaking process and explains how SIS intercepted, deciphered, and analyzed encoded messages. From its headquarters at Arlington Hall outside Washington, D.C., SIS grew from a staff of four novice codebreakers to more than 10,000 people stationed around the globe, secretly monitoring the communications of not only the Axis powers but dozens of other governments as well and producing a flood of intelligence. Some of the SIS programs were so clandestine that even the White House—unaware of the agency's existence until 1937—was kept uninformed of them, such as the 1943 creation of a super-secret program to break Soviet codes and ciphers. In addition, Alvarez brings to light such previously classified operations as the interception of Vatican communications and a comprehensive program to decrypt the communications of our wartime allies. He also dispels many of the myths about the SIS's influence on American foreign policy, showing that the impact of special intelligence in the diplomatic sphere was limited by the indifference of the White House, constraints within the program itself, and rivalries with other agencies (like the FBI). Drawing upon military and intelligence archives, interviews with retired and active cryptanalysts, and over a million pages of cryptologic documents declassified in 1996, Alvarez illuminates this dark corner of intelligence history and expands our understanding of its role in and contributions to the American effort in World War II.

This is the story of the U.S. Navy's communications intelligence (COMINT) effort between 1924 and 1941. It races the building of a program, under the Director of Naval Communications (OP-20), which extracted both radio and traffic intelligence from foreign military, commercial, and diplomatic communications. It shows the development of a small but remarkable organization (OP-20-G) which, by 1937, could clearly see the military, political, and even the international implications of effective cryptography and successful cryptanalysis at a time when radio communications were passing from infancy to childhood and Navy war planning was restricted to tactical situations. It also illustrates an organization plagues from its inception by shortages in money, manpower, and equipment, total absence of a secure, dedicated communications system, little real support or tasking from higher command authorities, and major imbalances between collection and processing capabilities. It explains how, in 1941, as a result of these problems, compounded by the stresses and exigencies of the time, the effort misplaced its focus from Japanese Navy traffic to Japanese diplomatic messages. Had Navy cryptanalysts been ordered to concentrate on the Japanese naval messages rather than Japanese diplomatic traffic, the United States would have had a much clearer picture of the Japanese military buildup and, with the warning provided by these messages, might have avoided the disaster of Pearl Harbor.