ES is a symmetric block cipher.

The same key is used to encrypt and decrypt the message.

The plain text and the cipher text are the same size.

The Aes algorithm works as follows:

Convert to state array: This step consists of conversion on the matrix onto a state array operating with the sbox.

Transformations (and their inverses)

AddRoundKey: Computing the round key for each round.

SubBytes: Substituting by bytes from Sbox.

ShiftRows: Shifting of rows.

MixColumns: Exor operation on columns.

Key Expansion: Expanding the key to be used on next round.