Advanced Encryption Standard (AES) is a symmetric block cipher used extensively in industry and government. The United States National Institute of Standards and Technology (NIST) developed AES to replace Data Encryption Standard (DES), for which various attacks began to be published.
In its requirements, NIST specified the new advanced encryption standard algorithm must be a block cipher capable of handling 128 bit blocks, using keys sized at 128, 192, and 256 bits.
The cipher itself was proposed by Belgian cryptographers Daemen and Rijmen as part of a NIST call for proposal for a new symmetric key algorithm. NIST required any proposals to be fully open to public scrutiny and comment, to ensure a thorough, transparent analysis of the designs submitted.
In October 2000, NIST published AES as U.S. FIPS PUB 197.