1. Using Algorithm 7.3 (MixColumns transformation), write the code for the CopyColumn routine. 2. Rewrite Algorithm 7.3 (MixColumns transformation) replacing the operators (.) with a routine called...

1. Using Algorithm 7.3 (MixColumns transformation), write the code for the CopyColumn routine.

2. Rewrite Algorithm 7.3 (MixColumns transformation) replacing the operators (.) with a routine called MultField to calculate the multiplication of two bytes in the GF(28 ) field.

3. Write an algorithm for InvMixColumns transformation.

4. Prove that the code in Algorithm 7.4 (AddRoundKey transformation) matches the process shown in Figure 7.15.

5. In Algorithm 7.5 (Key Expansion), a. Write the code for the SubWord routine. b. Write the code for the RotWord routine.

6. Give two new algorithms for key expansion in AES-192 and AES-256 (see Algorithm 7.5).