AES, a data encryption standard endorsed by the U.S. National Institute of Standards and Technology (NIST) as a replacement for the Data Encryption Standard (DES). AES offers far greater security than DES for communications and commercial transactions over the Internet.

In January 1997 NIST issued a public request for candidates to replace the aging DES, which resulted in 15 viable submissions from 12 countries. In October 2000 NIST announced that Rijndael, a program created by two Belgian cryptographers, Joan Daemen and Vincent Rijmen, had been accepted as the new standard, or the Advanced Encryption Standard (AES). The NIST predecessor, the National Bureau of Standards, had expected the DES to be implemented in special-purpose hardware and hence had given little or no consideration to its efficient implementation in software, i.e., using general-purpose microprocessors. As a result, the DES was unable to take advantage of the rapid development in microprocessors that occurred in the last two decades of the 20th century. The AES specifications, on the other hand, emphasized hardware and software implementations equally. In part, this recognized the needs of smart cards and other point-of-sale equipment, which typically have very limited computational capabilities, but more important was a recognition of the growing needs of the Internet and e-commerce. Based on their experience with the DES, where improvements in computing simply overran the work factor of the fixed 56-bit code key, NIST specifications for the AES also called for the algorithm to be capable of increasing the key length if necessary. Rijndael proved itself to be both small enough to be implemented on smart cards (at less than 10,000 bytes of code) and flexible enough to allow longer key lengths.

Based on the DES experience, there is every reason to believe the AES will not succumb to cryptanalysis, nor will it be overrun by developments in computing, as was the DES, since its work factor can easily be adjusted to outpace them.