Suppose Alice wants to send a message to Bob containing her name (N) and a request (R) for Bob. Alice uses a message authentication code MAC(NR) to send the message to Bob. Assume that Alice and Bob share a symmetric key kAB and have agreed on using a specific algorithm MAC_func which takes input parameters NR and kAB to produce MAC(NR) A) Outline the steps that Alice must follow for sending the message to Bob. B) Outline the steps that recipient Bob must follow for verifying the authenticity of message. C) MAC proves to Bob that a received message is authentic. Explain why? D) Bob is unable to prove to a third party that the message is authentic. Explain why