In February 2001, NIST announced that a draft of the Federal Information Processing Standard (FIPS) was available for public review and comment. Finally, AES was published as FIPS 197 in the Federal Register in December 2001.
The criteria defined by NIST for selecting AES fall into three areas:
1. Security 2. Cost 3. Implementation.
Objectives of Chapter 7: To review a short history of AES; to define the basic structure of AES; to define the transformations used by AES; to define the key expansion process; to discuss different implementations.
Symmetric Block Ciphers
Chương này sẽ đề cập với một số thuật toán mật mã khối quan trọng đã được phát triển trong quá khứ. Họ là IDEA (1992), RC5 (1995), rc6 (1996), DES (1977) và AES (2001). Advanced Encryption Standard (AES) xác định một thuật toán mã hóa FIPS-phê duyệt khối đối xứng sẽ sớm đến để được sử dụng thay cho Triple DES hoặc rc6.
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Advanced Encryption Standard competition began in 1997
Rijndael was selected to be the new AES in 2001
AES basic structures:
block cipher, but not Feistel cipher
encryption and decryption are similar, but not symmetrical
basic unit: byte, not bit
block size: 16-bytes (128 bits)
three different key lengths: 128, 192, 256 bits
AES-128, AES-192, AES-256
each 16-byte block is represented as a 4 x 4 square matrix, called the state matrix
the number of rounds depends on key lengths
4 simple operations on the state matrix every round (except the last round)