Given the following state array (in hex.) for an AES encryption round, perform the Sub Bytes step followed by the Shift Rows Step and write the output array (in hex.)

41 5a 6b 7c

9c 3d 4a 90

12 23 5e 4b

3c 2a 4d 2f

3. Use the output array of Q2 as the input array for an AES decryption round to perform the Inverse Shift Rows step followed by the Inverse Sub Bytes step and write the resulting state array.

4. Compute the 0th and the first 4×4 round key matrices w[0,3] and w[4,7] produced by the key expansion procedure in an AES crypto-system when the 128-bit key is all zeros.