The word Rijndael was made by combining portions of the last names of Vincent Rijmen and Joan Daemen, both of Belgium, to create a name for the algorithm they developed in response to the 1997 invitation by the National Institute of Standards and Technology (NIST) to submit an advanced algorithm. Twenty-one teams from 11 different countries offered submissions, and after the list was narrowed down to five finalists, Rijndael — pronounced either /RINE dahl/ or /RAIN dahl/ — was selected in 2000 to form the basis of then Advanced Encryption Standard (AES).
AES, is sometimes referred to as “AES (Rijndael).” It was created to replace the Data Encryption Standard (DES) and to be more secure. It is also used as a privacy transformation in Internet Protocol Security (IPSec), as well as in Internet Key Exchange (IKE). IKE takes advantage of public key cryptography in securely transmitting the secret key for decryption.
The United States government adopted AES for sensitive, but unclassified, documents, making it a Federal Information Processing Standard (FIPS), in this case, number 197. In 2003, the National Security Agency (NSA) approved AES using 192- and 256-bit keys for even top secret documents, and the European consortium NESSIE (New European Schemes for Signatures, Integrity, and Encryption) recommended it in the same year. In a sense, then, it has become a global standard.
The Belgian cryptologists who created Rijndael developed it from an earlier collaboration called Square. Rijndael is a block cipher, which means that the cryptographic key and algorithm are applied to data in a block rather than in individual bits. It is an alternative to a stream cipher. The cipher handles data in 128 bit blocks and supports 128, 156, and 192 bit keys.
Cryptography experts differ on whether Rijndael was the best choice for AES. Some say that no algorithm would have satisfied everyone. There are ongoing attacks on AES, as well as many people working on attacking block ciphers as a class. There are also bets being taken on whether AES is completely secure on the one hand, or whether will it will be broken by some specified dates.