Brigadier John Tiltman has been variously described as the greatest cryptanalyst of his time, the vest cryptanalyst ever to work for Government Communications Headquarters (CGHQ, Great Britain's counterpart to NSA), and a legend in his own time." He led the attack on numerous code and cipher systems over a dozen countries. At the same time he developed cipher systems for his own country that were unbreakable during the time they were used. He held the title of Chief Cryptographer for the Government Code and Cypher School. His career spanned two world wars, conflicts in Korea and Vietnam, and...

"Silent Warriors: The Naval Security Group Reserve, 1945-2005, recounts a unique and untold story, that of Naval Reserve (NR) cryptologists - the professional term for codebreakers and codemakers. This has always been a small and select community, one little known to outsiders, and even less understood. Cryptologists have long constituted the most secretive fraternity in America's armed forces, and Naval Reservists permitted to enter the cryptologic ranks set sail on a journey that placed them apart from the rest of the Naval Reserve, and far apart from their civilian lives. For six decades,...

For historians and many members of the informed public, the Japanese attack on Hawaii provoked "the never-ending story." Multiple official investigations and private historical inquiries into the attack and its background have generated enormous stocks of information about both the American and Japanese sides. It may well be that we know as much about December 7, 1941, as we do about any event in the last century, the Kennedy assassination possibly excepted. However, even with this virtual mountain chain of data, information gaps still exist, and many important questions remain under...

The cryptanalysts working for the Signals Intelligence Service (SIS) of the U.S. Army knew how crucial it was to decipher and read Japanese secret messages. But this new code, "Purple," wasn't breaking. For eighteen months the team struggled with this difficult Japanese diplomatic code. Then, one day in September 1940, Genevieve Grotjan made a discovery that would change the course of history. By analyzing and studying the intercepted coded messages, she found a correlation that no one else had yet detected. This breakthrough enabled other cryptanalysts to find similar links. Shortly...

The grimmest part of the World War II was the Holocaust. Following the war, a number of histories, memoirs, and specialized studies about the Holocaust were published. One element that was largely missing, however, was the records of the various Western intelligence agencies, such as the American Office of Strategic Services (OSS) and Britain's M.I.6. Also absent was the intelligence gathers by wartime Allies communications intelligence (COMINT) agencies. Beginning in the mid-1970's, scholars of the Holocaust who had wanted to utilize the archived material of the wartime code-breaking...

The National Security Agency is the Nation's cryptologic organization. NSA creates decisive U.S. strategic and tactical advantage by providing otherwise denied information to the U.S. decision makers while at the same time denying access to U.S. information and information systems by America's adversaries. The ability to understand the secret communications of our foreign adversaries while protecting our own communications - a capability in which the United States leads the world - gives our Nation a unique advantage. Signals Intelligence (SIGINT) and Information Assurance (IA) complement...