4. (10 points) A co-worker proposes the following protocol: Each plaintext block of 128 bits is encrypted with AES, and then XORed with the previous block of ciphertext. For the first block, the result is instead XORed with a randomly chosen initialization vector (IV). More formally: Cl E(Pl, K) 21 Then (IV, CO, CI, , CN will be transmitted across the network. The intended recipient is expected to have the key K, and therefore can decrypt easily What are some potential issues with this protocol