CODE BREAKING: A HISTORY AND EXPLORATION By Rudolf Kippenhahn Overlook Press 283 pp., $29.95
It was an incredible diplomatic blunder. In the grim World War I winter of 1916, Arthur Zimmerman, newly appointed director of the German Ministry of Foreign Affairs, had an idea. If the United States could somehow be drawn into war against Mexico, surely the Americans would be too preoccupied to interfere in the conflagration raging in Europe.
Zimmerman sent a coded telegram to Eckhardt, the German ambassador in Mexico City, plotting an alliance between Germany and Mexico to recapture Texas, Arizona, and California. Author Rudolph Kippenhahn relates how the telegram fell into the hands of the code breakers in Room 40, the secret London headquarters of British intelligence. Decoding the cable with the aid of a captured German diplomatic code, the British were able to inform President Wilson of the dastardly plan.
Wilson had been struggling to keep America out of the war, but this new outrage made his position untenable. America's entry into World War I in 1917 made it possible for the British and French to continue the fight and resulted in the total capitulation of the German Empire 19 months later. The punitive terms enforced by the victorious allies devastated the postwar German economy, leading directly to the social chaos resulting in the rise of Adolf Hitler. Code breaking had quite literally changed history.
This fascinating history of cryptology offers many equally remarkable stories, even for those whose deciphering skills are limited to Captain Marvel decoder rings. Kippenhahn, a former professor of astronomy and astrophysics at the University of Gottingen, Germany, is able to explain clearly the basis for various coding systems, from the secret writing of Julius Caesar to the notorious Enigma machine used by the Nazis in World War II.
Mathematicians specializing in number theory used to boast that their art was distinguished from the more practical disciplines in that nothing useful would ever come of it. In the final section of this book, the author effectively refutes this assertion. With the invention of the computer and the World Wide Web, concepts once of interest only to the specialist have become essential for business and personal communication all over the world.
Anyone ordering a gift on the Internet using a credit card has benefited from the work of the number theorists. Using sophisticated mathematical algorithms, it is possible to encode a message so that it cannot be decoded by anyone but the intended recipient even if intercepted on the way, as the British did to poor Zimmerman's telegram.
As the long history of cryptology amply demonstrates, however, anything that can be hidden can be found. As long as there are secrets to be concealed, there will be code makers and code breakers to challenge them.
*Frederick Pratter is a freelance writer in Missoula, Mont.