Computer Security and Cryptography pdf

Computer Security and Cryptography Wonderful Digest

1.6 CRYPTOGRAPHY AND HISTORY

David Kahn’s recent biography [Kahn, 2004] about Herbert O. Yardley relates the begin-ning of American cryptologic activities. Although Secretary of State Henry Stimson’s famous statement “Gentlemen do not read other people’s mail” marked a temporary end of official U.S. codebreaking activities in 1929, the intelligence needs of America,however, led to the establishment of a nongovernmental cryptanalysis effort.

Cryptography has played a significant role in the history of the United States, often providing our country with crucial information.

1. The Zimmerman telegram in January 1917, from the German Foreign Minister Zimmerman to the German Minister von Eckhardt in Mexico, offered to return ter-ritory to Mexico – perhaps Arizona and California – in exchange for Mexico’s support against the United States. Even better than a California driver’s license! Mexico declined!! British cryptanalysts deciphered the telegram, revealing the perfidy of the Germans. The impact on the American public was immense,causing the United States Congress to declare war on Germany in 1917.

2. The cryptanalysis of the German Enigma machine allowed the United States and Great Britain to read enciphered messages; the ability to read known messages led to victory in the Battle of the Atlantic against German U-boats.

3. The cryptanalysis of the Japanese PURPLE machine and its related “color” machines allowed the United States to prevail in the Battles of the Carol Sea and Midway. Deciphered Japanese messages gave the United States the route to be fol-lowed by Admiral Yamamoto Isoruku – the architect of the Japanese attack on Pearl Harbor – on a visit to his troops in the Pacific, leading to his death.