Consider the following key exchange protocol which is a variant of the Diffie-Hellman protocol. Each user P has a private key xP and public key gtP mod p. 1: A B: g'A mod p 2: B A: g mod p Shared Key K = grAxB + grBxA mod p. In the protocol, rA and r are randomly chosen in each session. a) Show the key derivation formulas of User A and User B (i.e., how does each user compute the shared key?) b) Does the man-in-the-middle attack against the textbook Diffie-Hellman protocol work against the above protocol? Justify your answer. c) Does the protocol provide Forward Secrecy? Justify your