The ShiftRows step:-The ShiftRows step operates on the rows of the state; it cyclically shifts the bytes in each row bya certain offset. For AES, the first row is left unchanged. Each byte of the second row is shiftedone to the left. Similarly, the third and fourth rows are shifted by offsets of two and threerespectively. For blocks of sizes 128 bits and 192 bits, the shifting pattern is the same. Row n isshifted left circular by n-1 bytes. In this way, each column of the output state of the ShiftRowsstep is composed of bytes from each column of the input state. (Rijndael variants with a largerblock size have slightly different offsets). For a 256-bit block, the first row is unchanged and theshifting for the second, third and fourth row is 1 byte, 3 bytes and 4 bytes respectively—thischange only applies for the Rijndael cipher when used with a 256-bit block, as AES does not use256-bit blocks. The importance of this step is to make columns not linear independent If so, AESbecomes four independent block ciphers.The mixcolumn step:-In the MixColumns step, the four bytes of each column of the state are combined using aninvertible linear transformation. The MixColumns function takes four bytes as input and outputsfour bytes, where each input byte affects all four output bytes. Together with ShiftRows,MixColumns provides diffusion in the cipher.During this operation, each column is multiplied by the known matrix that for the 128-bit key is: