3. Integrity (8 marks): (a) (2 marks) You are looking to implement a secure short message service, where each mes- sage is signed with RSA using a 2048-bit public modulus. Is the use of this cryptosystem going to require extra any further design consideration? (b) (6 marks) A MAC is sent together with the message as follows M, MAC(M). Consider the two modes of operation in Question 1.a. Discuss whether we could use these modes to construct a secure MAC (comment on both the use of Mode 1 and Mode 2). 3. Integrity (8 marks): (a) (2 marks) You are looking to implement a secure short message service, where each mes- sage is signed with RSA using a 2048-bit public modulus. Is the use of this cryptosystem going to require extra any further design consideration? (b) (6 marks) A MAC is sent together with the message as follows M, MAC(M). Consider the two modes of operation in Question 1.a. Discuss whether we could use these modes to construct a secure MAC (comment on both the use of Mode 1 and Mode 2)