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. (Dont use any IV.)

b. Decrypt the ciphertext 5628 using the above block cipher in CTR mode, with a counter that starts from 0. (Dont 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?

\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}