Cryptography

cryptography (krĬptŏg´rəfē) [Gr.,=hidden writing], science of secret writing. There are many devices by which a message can be concealed from the casual reader, e.g., invisible writing, but the term cryptography strictly applies to translating messages into cipher or code. The science of breaking codes and ciphers without a key is called cryptanalysis. Cryptology is the science that embraces both cryptography and cryptanalysis. In enciphering, each letter of the message is replaced by another letter or figure; in encoding, syllables, words, or whole sentences are treated. The code is the agreed upon set of rules whereby messages are converted from one form to another. The beginnings of cryptography can be traced to the hieroglyphs of early Egyptian civilization (c.1900 BC). Ciphering has always been considered vital for diplomatic and military secrecy; the Bible is replete with examples of ciphering, and many figures throughout history have written in ciphers, including Julius Caesar, Charlemagne, Alfred the Great, Mary Queen of Scots, and Louis XIV. Francis Bacon's celebrated biliteral cipher (1605) was an arrangement of the letters a and b in five-letter combinations, each representing a letter of the alphabet. This code illustrates the important principle that a code employing only two different signs can be used to transmit information. In the 20th cent. mathematical theory and computer science have both been applied to cryptanalysis. As the science of cryptology becomes increasingly sophisticated, most nations have found it necessary to develop special governmental bureaus to handle diplomatic and military security, e.g., the National Security Agency in the United States. The widespread use of computers and data transmission in commerce and finance is making cryptography very important in these fields as well. Recent successes in applying certain aspects of computer science to cryptography seem to be leading to more versatile and more secure systems in which encryption is implemented with sophisticated digital electronics. Industry and the U.S. government, however, have argued over who will have ultimate control over data encryption and, as a result, over government access to encrypted private transmissions.

See H. Gaines, Cryptanalysis (1956); J. R. Wolfe, Secret Writing (1970); D. Denning, Cryptography and Data Security (1982); C. A. Deavors and L. Kruh, Machine Cryptography and Modern Cryptoanalysis (1985); D. Kahn, The Codebreakers (rev. ed. 1996); S. Singh, The Code Book (1999).

The Columbia Encyclopedia, 6th ed. Copyright© 2013, The Columbia University Press.

Selected full-text books and articles on this topic

Cryptography: A Very Short Introduction
Fred Piper; Sean Murphy.
Oxford University Press, 2002
Forgotten Scripts: Their Ongoing Discovery and Decipherment
Cyrus H. Gordon.
Basic Books, 1982 (Revised edition)
Signals Intelligence in World War II: A Research Guide
Donal J. Sexton Jr.
Greenwood Press, 1996
Secret Science: Federal Control of American Science and Technology
Herbert N. Foerstel.
Praeger Publishers, 1993
The Shakespearean Ciphers Examined: An Analysis of Cryptographic Systems Used as Evidence That Some Author Other Than William Shakespeare Wrote the Plays Commonly Attributed to Him
William F. Friedman; Elizabeth S. Friedman.
Cambridge University Press, 1957
A Puzzle Even the Codebreakers Have Trouble Solving: A Clash of Interests over the Electronic Encryption Standard
Flynn, Sean M.
Law and Policy in International Business, Vol. 27, No. 1, Fall 1995
Code: And Other Laws of Cyberspace
Lawrence Lessig.
Basic Books, 1999
Cyberwars: Espionage on the Internet
Jean Guisnel.
Perseus Books, 1999
Mathematical Mysteries: The Beauty and Magic of Numbers
Calvin C. Clawson.
Perseus Books, 1996
Who Are We Protecting? A Critical Evaluation of United States Encryption Technology Export Controls
Levin, Staci I.
Law and Policy in International Business, Vol. 30, No. 3, Spring 1999
Taking Account of the World as It Will Be: The Shifting Course of U.S. Encryption Policy
Black, Tricia E.
Federal Communications Law Journal, Vol. 53, No. 2, March 2001
Codebreakers: The Inside Story of Bletchley Park
F. H. Hinsley; Alan Stripp.
Oxford University Press, 1994
National Cryptography Policy for the Information Age
Dam, Kenneth W.; Lin, Herbert S.
Issues in Science and Technology, Vol. 12, No. 4, Summer 1996
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