Security in Computing, Third Edition

2.6. The AES Encryption Algorithm

The AES is likely to be the commercial-grade symmetric algorithm of choice for years, if not decades. Let us look at it more closely.

The AES Contest

In January 1997, NIST called for cryptographers to develop a new encryption system. As with the call for candidates from which DES was selected, NIST made several important restrictions. The algorithms had to be

• unclassified

• publicly disclosed

• available royalty-free for use worldwide

• symmetric block cipher algorithms, for blocks of 128 bits

• usable with key sizes of 128, 192, and 256 bits

In August 1998, fifteen algorithms were chosen from among those submitted; in August 1999, the field of candidates was narrowed to five finalists. The five then underwent extensive ...