Question: Two parties, A and B , agree to securely communicate using a shared secret key, K , exchanged with the help of Diffie - Hellman

Two parties, A and B, agree to securely communicate using a shared secret key, K, exchanged with the help of Diffie-Hellman key exchange method. Both A and B, choose a prime number p, its primitive root g, and a hash function H. User A chooses a random number a and computes M1= ga mod p. For authentication purpose, A chooses a nonce N1, and sends M, and N, to B. While receiving M, and N1, B computes M2= gb mod p by choosing b as the random number. It also computes the hash of N, as H(N) and sends M2, H(N), and its own nonce Na to A. Upon receiving M2, H(N), and NB, A verifies the received hash H(N) and computes the key as K =(M) mod p. It also computes the hash of Ng as H(Na) and sends it to B. Similarly, B computes the key as K =(M) mod p and verifies the received hash H(Na). Consider an adversary, E, which intercepts all communication between A and B, and knows the parameters p and g. If E does not have any information about the hash function H, describe with proper reasoning whether it would be possible for E to get the secret key K and to establish the man-in-the-middle attack? Support your answer with clear and justified reasoning.

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