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3.5.1 What is DES?

  DES is the Data Encryption Standard, an encryption block cipher defined and endorsed by the U.S. government in 1977 as an official standard; the details can be found in the official FIPS publication. It was originally developed at IBM. DES has been extensively studied over the last 15 years and is the most well-known and widely used cryptosystem in the world.

DES is a secret-key, symmetric cryptosystem: when used for communication, both sender and receiver must know the same secret key, which is used both to encrypt and decrypt the message. DES can also be used for single-user encryption, such as to store files on a hard disk in encrypted form. In a multi-user environment, secure key distribution may be difficult; public-key cryptography was invented to solve this problem (see Question 3.1.3). DES operates on 64-bit blocks with a 56-bit key. It was designed to be implemented in hardware, and its operation is relatively fast. It works well for bulk encryption, that is, for encrypting a large set of data.

NIST (see Question 3.7.1) has recertified DES as an official U.S. government encryption standard every five years; DES was last recertified in 1993, by default. NIST has indicated, however, that it may not recertify DES again.


next up previous
Next: 3.5.2 Has DES been Up: 3.5 DES Previous: 3.5 DES
Denis Arnaud
12/19/1997