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Columbia Encyclopedia entry: cryptography
Cryptographykrĭptŏg'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 B.C.). 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. Copyright © 2001-09 Columbia University Press. All rights reserved.

Wikipedia search results for: Cryptography
From Wikipedia, the free encyclopedia
Cryptography is the practice and study of hiding information. Modern cryptography intersects the disciplines of mathematics, computer science, and engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce. Until modern times cryptography referred almost exclusively to encryption, which is the process of converting ordinary information into unintelligible gibberish. Decryption is the reverse, in other words, moving from the unintelligible ciphertext back to plaintext. A cipher is a pair of algorithms which create the encryption and the reversing decryption. The detailed operation of a...more »
Columbia Encyclopedia search results: cryptography
Results 1 - 4  of 4
  • Wallis, John

    Wallis, John, 1616–1703, English mathematician. He was Savilian professor of geometry at Oxford from 1649. He systematized the use of formulas, introduced the symbol ∞ for infinity, and made a...

  • code, in communications

    Code, in communications, set of symbols and rules for their manipulation by which the symbols can be made to carry information. By this extended definition all written and spoken languages are...

  • data encryption

    Data encryption, the process of scrambling stored or transmitted information so that it is unintelligible until it is unscrambled by the intended recipient. Historically, data encryption has b...

  • espionage

    Espionage, the act of obtaining information clandestinely. The term applies particularly to the act of collecting military, industrial, and political data about one nation for the benefit of a...

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