ABSTRACT
Cryptography Overview Cryptography, from the Greek words “kryptos” and “graphin” for hidden and secret writing, has a broader meaning for protecting electronic information during transmission and in storage. Œe birth of writing, depending on one’s perspectives of ideographs, mnemonic symbols, or phonetic writing, seems to be somewhere between 8000 and 6000 years old. Cryptography, by comparison, is a 4000-year-old technology attributed to an Egyptian scribe using unusual hieroglyphics carved about 1900 BC in the main tomb chamber of the nobleman Khnumhotep II. One of the more well-known ancient methods is the Caesar Cipher based on the Grecian writer Polybius’ signaling system used by Julius Cesar during the Gallic Wars. Another well-known historical method is the Je‰erson Wheel based on the French Vigenére cipher used by the U.S. Army in World War I.1 World War II ushered in the modern cryptography era, notably with the declassi‚cation and publication of Claude Shannon’s paper “Œe Communication Œeory of Secrecy Systems,” published in the Bell System Technical Journal in 1949.2
Information security a‰orded by modern cryptography includes data con‚dentiality, integrity, authenticity, nonrepudiation, and reliability.3 Modern cryptography is based on mathematically “hard” problems translated into algorithms or schemes. Algorithms are the basic building blocks with a precise set of rules having speci‚c inputs and outputs. Schemes are more general in nature, characteristically using one or more algorithms in an orderly fashion to achieve a particular information security goal such as data encryption, digital signature, or establishing cryptographic keys. Protocols are implementations of a particular scheme incorporating algorithms, con‚guration parameters, inputs, and outputs.
