AES and the Wide Trail Design Strategy

Rijndael is an iterated block cipher that supports key and block lengths of 128 to 256 bits in steps of 32 bits. It transforms a plaintext block into a ciphertext block by iteratively applying a single round function alternated by the addition (XOR) of a round keys. The round keys are derived from the cipher key by means of a key schedule. As a result of the wide trail strategy, the round function of Rijndael consists of three dedicated steps that each have a particular role. Rijndael versions with a block length of 128 bits, and key lengths of 128, 192 and 256 bits have been adopted as the Advanced Encryption Standard (AES).