Question 1 Describe how a block cipher works by drawing a simple diagram showing all the components of the operation. Question 2 What is the codebook attack? Why this attack is feasible when 16 or 32-bit blocks have been used; but not feasible when 64-bit blocks have been used? Question 3 Describe two methods for constructing block ciphers. What is a round in block ciphers? How a slide attack is realized? Question 4 Compare EBC and CBC modes of operations? Why one should not use EBC? How the plaintext messages whose length is not a multiple of the block length is encrypted by using CBC? Question 5 Explain the Padding Oracle Attack.