Advanced Encryption Standard

Template:TOC-right The Advanced Encryption Standard, or AES, is a US government specification for a block cipher to replace the earlier and weaker Data Encryption Standard (DES).

AES encrypts data in 128-bit blocks and can take a 128, 192 or 256-bit key. DES used 64-bit blocks and a 56-bit key.

Starting in the late 90s, the US National Institute of Standards and Technology (NIST) ran a contest to find a block cipher to replace DES. The result is the Advanced Encryption Standard. In October 2002, they announced [1] the winner — Rijndael (pronounced approximately "rhine doll"), from two Belgian designers.

The NIST page on AES [2] has much detail, including links to all the Rinjdael design documents, to several implementations, and to the official standard, approved as FIPS 197,

Because of the birthday attack, a hash algorithm needs to provide output of 2n bits to resist attacks as well as a cipher with an n-bit key. NIST has therefore issued standards for the SHA-2 family of hashes — SHA-256, SHA-384 and SHA-512 to match the strength of AES, plus SHA-224 to match the 112-bit strength of Triple DES. However, those hashes are all derived from SHA and some weaknesses (minor so far) have been shown in that, so in 2008 NIST started a contest similar to the AES contest to design an Advanced Hash Standard which can (if it proves necessary) replace SHA-2 as AES replaced DES.