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On January 2, 1997 the National Institute of Standards and Technology, or NIST, called for cryptographers to propose a new standard block cipher for United States Government use in non-classified but sensitive applications. (Knowledge of what is used for classified applications is itself classified.) The Advanced Encryption Standard (AES) was intended to replace Triple DES, itself a interim fix for the aging Data Encryption Standard (DES). The primary motivation for a new standard was the fact that DES has a relatively small 56-bit key which was becoming vulnerable to brute force attacks. In addition the DES was designed primarily for hardware and is relatively slow when implemented in software. While Triple-DES avoids the problem of a small key size, it is very slow in software, and also unsuitable for limited-resource platforms.Since the specification for the AES is not secret, it is expected that the cipher will also see much use in non-government applications, and outside the US. This was the case for its predecessors DES and Triple-DES.
The requirements for the new standard were quite tough. A block size of 128 bits was specified, and key sizes of 128, 192, and 256 bits had to be supported. The cipher had to be secure and speed was also considered important. It also had to be capable of running in extremely small embedded systems with limited amounts of RAM and ROM.
Fifteen different designs were submitted from several different countries. They were, in alphabetical order:
- CAST-256In cryptography, CAST-256 (or CAST6 is a block cipher published in June 1998 and submitted as a candidate for the Advanced Encryption Standard (AES). It is an extension of an earlier cipher, CAST-128; both were designed according to the "CAST" design meth, CRYPTON , DEALIn cryptography, DEAL Data Encryption Algorithm with Larger blocks is a block cipher derived from the Data Encryption Standard (DES). The design was proposed in a report by Lars Knudsen in 1998, and was submitted to the AES contest by Richard Outerbridge, DFC , E2 , FROGIn cryptography, FROG is a block cipher authored by Georgoudis, Leroux and Chaves. The algorithm can work with any block size between 8 and 128 bytes, and supports keys sizes betweens 5 and 125 bytes. The algorithm consists of 8 rounds and has a very comp, HPC , LOKI97In cryptography, LOKI97 is a block cipher which was a candidate in the Advanced Encryption Standard competition. It is a member of the LOKI family of ciphers, earlier instances being LOKI89 and LOKI91. LOKI97 was designed by Lawrie Brown, assisted by Jenn, MAGENTA, MARSIn cryptography, MARS is a block cipher which was IBM's submission to the Advanced Encryption Standard (AES) process; the cipher was selected as a finalist. The design team included Don Coppersmith who had been involved in the creation of the previous Dat, RC6In cryptography, RC6 is a symmetric key block cipher derived from RC5. It was designed by Ron Rivest, Matt Robshaw, Ray Sidney, and Yiqun Lisa Yin to meet the requirements of the Advanced Encryption Standard (AES) competition. The algorithm was one of the, Rijndael, SAFER+, Serpent, and Twofish.
Some were found to be less secure than required, but for most no attacks of significance were found. A shortlist of five designs was selected for Round 2 of the selection process:
- MARS, RC6, Rijndael, Serpent, and Twofish.
On October 2, 2000, NIST announced that Rijndael had been selected as the proposed AES, and underwent the process of being made the official standard. On November 26, 2001, NIST announced that AES was approved as FIPS PUB 197.
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