4. This question is about SSL. (a) Describe the use of public key and private key encryption systems in SSL (Secure Socket Layer) protocol. Specifically address the two phases of SSL and specify the algorithms used in each. (4 points) (b) What is the role of the CA (Certificate Authority) in SSL? Explain the structure of the message send by the CA to the client. How is the integrity of the messages ensured? What algorithms are used for this purpose? (5 points) (c) Describe the structure of the SSL packet and comment on the purpose of using different cryptographic algorithms. (4 points)