5.1.5 The ‘State’

The AES algorithm is a block cipher, which means that data is managed in blocks. For the AES cipher, the block size is 16 bytes. The AES block is often organized in a 4x4 array called the ‘State’ or the ‘State array’. The leftmost column of the State holds the first four bytes of the block, from top to bottom, and so on. The reader should also be aware that in the AES specification, four consecutive bytes are referred to as a word.