1. Show that if the DES key K encrypts M to C, then K' encrypts M' to C'. That is: DESK (P) = C then DESK (P') C' 2. Show that AES decryption is indeed the inverse of the AES encryption. 3. Suppose you saw a ciphertext stream encrypted using CBC mode that have c = c; (i + j)? What information does this leak about the plaintext?