Cryptology

The science of protecting, disguising, or encrypting communications. Cryptology is widely used by the military and federal security and law enforcement agencies to protect sensitive communications from being intercepted or read by unauthorized persons. The dramatic increase in computer use by government agencies in recent years has increased the use of electronic [Page 174]cryptography to protect computerized data that are vital to national security.

The first recorded use of cryptography was in ancient Greece, where the Spartans employed a system of encoded military communications. The Roman ruler Julius Caesar invented a system of letter substitutions to encrypt messages so that they could only be read by someone who also knew the code. Medieval Arab scientists were the first to study and systematically describe the principles of cryptography and cryptanalysis. Some of the techniques developed by the Arabs are still in use today.

World War II presented unique opportunities for cryptographers working with both old and new encryption technology. One decidedly low-tech but astoundingly effective effort was the use of Navajo codetalkers in the Pacific theater. Navajo Indians working for the U.S. Army used their language to send secret messages through radio broadcasts. The Navajo language was ideal for the job because it has no written alphabet (which meant the messages had to be verbal), and even within the Navajo tribe, very few people at the time still spoke or understood the language. Despite their best efforts, the Japanese never broke the code.

On the high-tech end of developments in cryptography was a mechanical revolution: For the first time, machines took over the majority of cryptographic work. The most notable example was the Enigma machine, a mechanical encrypting device employed by the German navy. With the help of Polish code breakers, a remarkable team of mathematicians broke the Enigma machine's code at Bletchley Park in England in the late 1930s. Prominent among that group of code breakers was Alan Turing, considered by many to be one of the fathers of modern computing.

In today's world, cryptology is closely interwoven with computer science and implemented in hardware and software. Sophisticated software programs are used to encrypt and decode electronic communications, and high-powered computers have been developed specifically for the purpose of data encryption and decryption. In the United States, this technology is considered a weapon and covered by the International Traffic in Arms Regulations under the control of the president. Software or hardware with enhanced cryptographic capabilities cannot be sold to a foreign national without government approval. Concern that terrorists or criminals would use encryption to send undecipherable messages led to an effort by the administration of President Bill Clinton to ban the export of so-called strong-encryption technology. Although implemented for a brief period, the ban was lifted in 1999.

Continued rapid increases in computing power have led some experts to predict that the balance between cryptography and cryptanalysis will soon shift in favor of cryptographers. At the same time, however, more powerful computers will also allow for faster, large-scale decryption. This presents a major challenge to those charged with protecting sensitive U.S. national security information.

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