5. (a) What is the Public Key Cryptography? Describe it in at least three sentences. (b) Transport Layer Security provides session Security for web site connections. Describe how it can be used to deliver secure session keys in a symmetric encryption that uses TLS. Please detailed description step by step. (c) If the private key of a network server is stolen, describe a possible attack on the network and how the network administrator should take action against the attack (d) Public key encryption can provide more security, so why not use it to encrypt the entire session? Please do not use your own words to answer questions, do not copy and paste from anywhere