Question

Which statement correctly explains why the classic, unauthenticated Diffie-Hellman key exchange is vulnerable to a man-in-the-middle attack?

Q: Answer-Which statement correctly explains why the classic, unauthenticated Diffie-Hellman key exchange is v...

Plain Diffie-Hellman protects the derived key from passive eavesdroppers but includes no mechanism to verify who sent which public value. An active attacker can sit in the middle, completing one DH exchange with the client and a separate one with the server, then transparently decrypt, read, and re-encrypt all traffic. This is precisely why real-world protocols like TLS combine DH with digital signatures or certificates for authentication.

A Because the discrete logarithm problem becomes computationally easy once an eavesdropper intercepts the public values exchanged

B Because both parties are required to reuse the same private exponent across multiple sessions, enabling key recovery

C Because the derived shared secret is transmitted in plaintext during the final step of the exchange

D Because the modulus used in the exchange is generally too small to resist brute-force factorization by modern hardware

E Because Diffie-Hellman does not authenticate the identities of the communicating parties, allowing an attacker to negotiate separate shared secrets with each party while relaying traffic between them

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Which statement correctly explains why the classic, unauthenticated Diffie-Hellman key exchange is vulnerable to a man-in-the-middle attack?

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