Hello, please write with full explanation because I will be using it for understanding and revision purposes. This regards Computer Security. Thank you.

a) Propose how a message authentication code (MAC) can be used to achieve a key security principle. In your answer you should explain how a MAC operates and propose one mechanism that can be used to implement a MAC. b) State one possible attack on a MAC and thus propose a solution to this attack. You should explain how your solution operates and how it mitigates or stops the attack