Wireless Mobile Internet Security, 2nd Edition

Chapter 4

Symmetric Block Ciphers

This chapter deals with some important block ciphers that have been developed in the past. They are IDEA (International Data Encryption Algorithm; 1992), RC5 (1995), RC6 (1996), DES (Data Encryption Standard; 1977), and AES (Advanced Encryption Standard; 2001). The AES specifies an FIPS-approved symmetric block cipher, which will soon come to be used in lieu of Triple DES or RC6.

4.1 Data Encryption Standard (DES)

In the late 1960s, IBM initiated a Lucifer research project, led by Horst Feistel, for computer cryptography. This project ended in 1971 and LUCIFER was first known as a block cipher that operated on blocks of 64 bits, using a key size of 128 bits. Soon after this IBM embarked on another effort to develop a commercial encryption scheme, which was later called DES. This research effort was led by Walter Tuchman. The outcome of this effort was a refined version of Lucifer that was more resistant to cryptanalysis.

In 1973, the National Bureau of Standards (NBS), now the National Institute of Standards and Technology (NIST), issued a public request for proposals for a national cipher standard. IBM submitted the research results of the DES project as a possible candidate. The NBS requested the National Security Agency (NSA) to evaluate the algorithm's security and to determine its suitability as a federal standard. In November 1976, the DES was adopted as a federal standard and authorized for use on all unclassified US government communications. ...