Cryptographers need to provide the world with a new encryption standard. DES, the major encryption algorithm for the past fifteen years, is nearing the end of its useful life. A more recent attack called XSL, proposes a new attack against AES and Serpent. Ciphers with small S-boxes and simple structures are particularly vulnerable. Serpent has small S-boxes and a simple structure. AES has larger S-boxes, but a very simple algebraic description. Many of the other unbroken algorithms -Khufu, REDOC II, and IDEA-are protected by patents. RC2 is broken. The U.S. government has...