Advanced Encryption Standard. This standard, developed conjointly by the U.S. National Institute of Standards and Technology (NIST) and the international cryptographic community, specifies an encryption algorithm capable of protecting information well into the 21st century. It replaces the outdated Data Encryption Standard (DES). The Rijndael algorithm was selected as the finalist in the NIST's evaluation process after seeing submissions from 21 teams of cryptographers from 11 countries.