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