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) .
