The Development of Monitors

The Development of Monitors

By:

Professor

If you want to keep information secret, you have two possible strategies: hide the existence of the information, or make the information unintelligible. Cryptography is the art and science of keeping information secure from unintended audiences, of encrypting it. Conversely, cryptanalysis is the art and science of breaking encoded data. The branch of mathematics encompassing both cryptography and cryptanalysis is cryptology. This method of secrecy has existed since 1900 B.C. in the form of Egyptian hieroglyphs. Up to the present two organizations have come to the front of the field; United States' National Security Agency (NSA) and United Kingdom's Government Communications Headquarters (GCHQ). In order to understand these institutions in their current state one must know their origins.

NSA

Although the National Security Agency is only forty-five years old (established by order of President Harry S. Truman in 1952), the functions it performs have been part of human history for thousands of years. The need to safeguard one's own communications while attempting to produce intelligence from foreign communications has long been a recognized part of governmental activity.

In the American experience, cryptologic efforts can be traced to the very beginnings of the American nation. George Washington employed Elbridge Gerry (later Vice President of the United States) to solve the suspected cryptograms of a Tory spy, Dr. Benjamin Church. Thomas Jefferson included the making of codes and ciphers among his many interests, putting his efforts to use in both private correspondence and public business. One of his inventions, the cipher wheel, has been described as being in "the front rank" of cryptologic inventions.

The American Civil War created a new urgency for techniques in both cryptography (the manufacture of codes and ciphers) and cryptanalysis (the breaking of codes and ciphers). It also introduced new elements into both processes -- telegraphy and significant advances in the use of signal flags and torches. These methods of transmitting information permitted rapid communication from one outpost to another or from a commander to his subordinates, but also brought with them new dangers of the loss of that information to an enemy. Both sides considered telegraph lines major targets and attempted either to cut or tap them.

Cryptology again proved to be of great significance in the First World War, as evidenced by British decryption of the famous Zimmermann Telegram. In an effort to keep the United States from playing an effective role in the war in Europe, Germany offered Mexico the opportunity to regain Texas and other territories lost to the United States during the nineteenth century, in return for a Mexican declaration of war against the U.S. The telegram backfired, as its release by British authorities brought the U.S. closer to war with Germany. Tactically, the First World War introduced wireless communications to the battlefield, increasing flexibility but making codes and ciphers even more essential in guaranteeing security.

After the armistice of 1918, the United States maintained modest but significant cryptologic establishments in the Navy and War Departments, along with an interdepartmental effort conducted in New York and headed by Herbert O. Yardley.

HERBERT O. YARDLEY

Born in 1889 in Indiana, Herbert O. Yardley began his career as a code clerk in the State Department. He accepted a Signal Corps Reserve commission and served as a cryptologic officer with the American Expeditionary Forces in France during the First World War. In the 1920s he was chief of MI-8, the first U.S. peacetime cryptanalytic organization, jointly funded by the U.S. Army and the Department of State. In that capacity, he and a team of cryptanalysts exploited nearly two dozen foreign diplomatic cipher systems. MI-8 was disbanded in 1929 when the State Department withdrew its share of the funding.

Out of work, Yardley caused a sensation in 1931 with the publication of his memoirs of MI-8, "The American Black Chamber". In this book, Yardley revealed the extent of U.S. cryptanalytic work in the 1920s. Surprisingly, the wording of the espionage laws at that time did not permit prosecution of Yardley. (This situation was changed two years later with a new law imposing stiff penalties for unauthorized revelations of cryptologic secrets.)

Yardley did some cryptologic work for Canada and China during the Second World War, but he was never again given a position of trust in the U.S. government.

On August 7, 1958, Herbert O. Yardley, one of the pioneers