AES is a standard based on the Rijndael algorithm. For AES, the length of the input and State is constant and equals 128 bits, and the length of the cipher key K is 128, 192, or 256 bits. At the same time, the original Rijndael algorithm allows a key length and block size from 128 to 256 bits in 32-bit increments. To denote the selected lengths of input, State, and Cipher Key in 32-bit words, the notation Nb = 4 for input and State, Nk = 4, 6, 8 for Cipher Key, respectively, for different key lengths is used.

* — the key can be any characters