1. (10 pts) In section 6.4.2 of Network Security: Private Communication in a Public World, Second Edition, Defenses Against Man-in-the-Middle Attack, it states that encrypting the Diffie-Hellman value with the other side's public key prevents the attack. Why is this the case, given that an attacker can encrypt whatever it wants with the other side's public key? Charlie Kaufman, Radia Perlman, and Mike Speciner, Network Security: Private Communication in a Public World: Second Edition, Prentice Hall PTR, 2002. https://learning.oreilly.com/library/viewetwork-securityprivate /9780137155880/ 2. (15 pts) Describe and explain your choices for the solutions you would recommend to provide the following security elements for an 802.11 wireless network: user authentication, communications confidentiality, communications integrity. 3. a) (10 pts) Is the following three-message mutual authentication protocol secure? Alice initiates contact with Bob. Bob is a stateless server so he cannot remember the challenge that he sends to Alice. Thus Alice replies with both the encrypted challenge and the response. Give the reasoning behind your answer. b) (10 pts) Suppose Bob encrypts the challenge with his own key and sends that as well and Alice includes that in her reply instead. Would this protocol be secure, why or why not? 4. (15 pts) Describe an attack that might be used to intercept a SIP-based phone call. Then describe a technique that could be used to block the attack