Assume that Alice and Bob share a secret key KAB. Let g be a generator of group Zp, where the discrete logarithm problem is hard. Describe a protocol that allows Alice and Bob to establish a session key. The protocol should provide perfect forward secrecy (i. e., the session key will not be compromised even if the secret key KAB is compromised) and be resilient to the man-in-the-middle attack.