AES is intended to be a stronger，more efficient successor to Triple Data Encryption Standard (3DES)，which replaced the aging DES，which was cracked in less than three days in July 1998．

　　“Until we have the AES，3DES will still offer protection for years to come．So there is no need to immediately switch over，”says Edward Roback， acting chief of the computer security division at NIST and chairman of the AES selection committee．“What AES will offer is a more efficient algorithm．It will be a federal standard，but it will be widely implemented in the IT community．”

According to Roback，efficiency of the proposed algorithms is measured by how fast they can encrypt and decrypt information，how fast they can present an encryption key and how much information they can encrypt．

　　The AES review committee is also looking at how much space the algorithm takes up on a chip and how much memory it requires．Roback says the selection of a more efficient AES will also result in cost savings and better use of resources．

　　“DES was designed for hardware implementations，and we are now living in a world of much more efficient software，and we have learned an awful lot about the design of algorithms，”says Roback．“When you start multiplying this with the billions of implementations done daily，the saving on overhead on the networks will be enormous．”

　The process of selecting the algorithm for AES has been notable for its openness and transparency．This is a marked departure from the government's past inclination toward secrecy in discussing encryption standards，which led to the public cracking of DES after critics questioned the government's assertion that the standard was still secure．

　　NIST kicked off the selection process in September 1997．Conferences were held in August 1998 and March 1999 ；cryptographers from around the world discussed the algorithm candidates and helped narrow the list to 15 and then to five finalists：IBM's MARS；RSA Laboratories* RC6 ；Joan Daemen and Vincent Rijmen's Rijndael；Ross Andersen，Eli Baham and Lars Knudsen's Serpent；and Counterpane Labs* Twofish．

While most evaluators of the algorithms want to avoid complexity by selecting one to serve as a standard，there's a minority that wants to select more than one．

　　在过去三年中，（美国）国家标准与技术局（NIST）已在研究开发一种新的加密标准，以确保政府的信息安全。该组织目前正处于为新的先进加 密标准（AES）选择一个或几个算法或数据打乱公式的开放过程的最后阶段，并计划在夏末或秋初作出决定。此标准内定明年实施。

　　AES预定为比三层数据加密标准(3DES)更强、更高效的后续标准，3DES替代了老化的DES加密标准，DES在1998年7月在不到三天的时间内就 被破译了。 http://www.xuexi86.com