Data Encryption Standard (DES)

A standard that protects passwords from being read and then used again on the same a network to obtain unofficial access. It s also known as the Federal Information Processing Standard (FIPS) 46-1, or the Data Encryption Algorithm (DEA). The DEA is also defined in the ANSI standard X9.32. DES was developed in the 1970s in a joint effort by IBM, the National Bureau of Standards and the National Security Agency (NSA). Its purpose is to provide a standard method for protecting sensitive commercial and unclassified data. IBM created the first draft of the algorithm, calling it LUCIFER. DES became a Federal standard in November 1976.

For communications purposes, both sender and receiver using DES / DEA must know the same secret key, which can be used to encrypt and decrypt the message, or to generate and verify a Message Authentication Code (MAC). DES performs essentially only two operations on its input: Bit shifting and bit substitution. The key controls exactly how this process works. Performing these operations repeatedly in a non-linear fashion eventually generates a result which cannot be used to retrieve the original without the key, a one way function that will be familiar to those acquainted with chaos theory. Through the successive application of simple operations a system can achieve a state of near total randomness, which leads to what every crypto aficionado is attempting to achieve a message or file appearing so random that it is immune to easy decryption.

DES works...