Suppose that Alice and Bob share a 4-digit PIN number, X. An approach to establish a shared symmetric key with Diffie-Hellman is using the X to encrypt packages for key exchange. That is, Alice computes and sends E(g" mod p, X) and Bob computes and sends E(g mod p, X). Alice Elg mod p. X) Eg mod p. X) Bob (a) (2pt) Is this new Diffie-Hellman method secure from the man-in-the-middle at- tack? (b) (6pt) Please explain why it is secure or not.