Problem 1 Suppose that ???? is a MAC for fixed-length messages (of length b) and that ???? is unforgeable under adaptive chosen message attacks. Construct a MAC Tagk for variable length messages as follows. Given a message M, break into blocks Mo, Mi,.. Mn of length b (padding the last block with the appropriate string of the form 10). Let True or False: TagK (M) is unforgeable under chosen message attack. Prove your answer. Problem 1 Suppose that ???? is a MAC for fixed-length messages (of length b) and that ???? is unforgeable under adaptive chosen message attacks. Construct a MAC Tagk for variable length messages as follows. Given a message M, break into blocks Mo, Mi,.. Mn of length b (padding the last block with the appropriate string of the form 10). Let True or False: TagK (M) is unforgeable under chosen message attack. Prove your