Suppose Alice wants to communi

Suppose Alice wants to communicate with Bob using symmetric key cryptography using a session key K_s In Section 2.2, we learned how public-key cryptography be used to distribute the session key from Alice to Bob. In this problem, we explore how the session key can be distributed without public key cryptography using a key distribution center (KDC). The KDC is a server that shares a unique secret symmetric key with each registered user. For Alice and Bob, denote these keys by KA-KDC and KB- KDC. Design a scheme that uses the KDC to distribute K_s to Alice and Bob. Your scheme should use three messages to distribute the session key: a message from Alice to the KDC; a message from the KDC to Alice; and finally a message from Alice to Bob.