Assume there is a Certificate Authority (CA) with a well-known public key. Further assume every user is issued a certificate for his/her public key. For convenience, we use PKu and SKu to represent user u's public key and private key, respectively. Draw diagrams to answer the following questions.
(a) Suppose Alice wants to send a large secret message M to Bob. Describe how Alice should send M in an authenticated way.
(b) Assume Bob receives the message sent by Alice. Describe how Bob should process the message.