Mastering Blockchain - Second Edition

How AES works

During AES algorithm processing, a 4 x 4 array of bytes known as the state is modified using multiple rounds. Full encryption requires 10 to 14 rounds, depending on the size of the key. The following table shows the key sizes and the required number of rounds:

Key size	Number of rounds required
128-bit	10 rounds
192-bit	12 rounds
256-bit	14 rounds

Once the state is initialized with the input to the cipher, four operations are performed in four stages to encrypt the input. These stages are: AddRoundKey, SubBytes, ShiftRows, and MixColumns:

1. In the AddRoundKey step, the state array is XOR'd with a subkey, which is derived from the master key
2. SubBytes is the substitution step where a lookup table (S-box) ...