Data Encryption Standard (DES)
Bruce Schneier · 2015
This chapter discusses the history, security and variants of data encryption standard (DES) known as the data encryption algorithm. People have long questioned the security of DES. There has been much speculation on the key length, number of iterations, and design of the S-boxes. The author's recommendation is to use Biham's construction for key-dependent S-boxes. It is easy to implement in software and in hardware chips that have loadable S-boxes, and has no performance penalty over DES. It increases the algorithm's resistance to a brute-force attack, makes differential and linear cryptanalysis harder, and gives the National Security Agency (NSA) something at least as strong as DES, but different, to worry about.