John works as a professional Ethical Hacker. He has been assigned the project of testing the security of www.we-are-secure.com. John notices that the We-are- secure network is vulnerable to a man-in-the-middle attack since the key exchange process of the cryptographic algorithm it is using does not thenticate participants. Which of the following cryptographic algorithms is being used by the We-are-secure server? 

Answer options:

A. Blowfish
B. Twofish
C. RSA
D. Diffie-Hellman

D