\begin{tabular}{|c|c||c|c|} \hline Plaintext & Ciphertext & Plaintext & Ciphertext \\ \hline 0 & a & 8 & e \\ \hline 1 & c & 9 & d \\ \hline 2 & f & a & 0 \\ \hline 3 & 6 & b & 7 \\ \hline 4 & 3 & c & 5 \\ \hline 5 & 8 & d & b \\ \hline 6 & 4 & e & 9 \\ \hline 7 & 2 & f & 1 \\ \hline \end{tabular} ( 6 pts) For this question, you will perform encryption and decryption using the same cipher described above, but in CBC mode. Recall that you can convert hexadecimal digits to binary to do the XOR operation. a. Encrypt the 4-block message dea1 using the above block cipher in CBC mode with an IV of 6 (0110 in binary). b. Decrypt the ciphertext db70 using the above cipher in CBC mode with an IV of 6. (6 pts) For this question, you will perform encryption and decryption using the same cipher described above, but in CTR mode. a. Encrypt the message dea1 using the above block cipher in CTR mode, with a counter that starts from 0 . (Don't use any IV.) b. Decrypt the ciphertext 5628 using the above block cipher in CTR mode, with a counter that starts from 0. (Don't use any IV.) c. Was this easier or more difficult than encrypting/decrypting in CBC mode? Do you suspect any difference in security? Why or why not