Design a secure two-message authentication protocol that provides mutual authentication and establishes a session key K. Assume that Alice and Bob know each other's public keys beforehand. Does your...

Design a secure two-message authentication protocol that provides mutual authentication and establishes a session key K. Assume that Alice and Bob know each other's public keys beforehand. Does your protocol protect the anonymity of Alice and Bob from a passive attacker (i.e., an attacker who can only observe messages sent between Alice and Bob)? If not, modify your protocol so that it does provide anonymity.