What is the key difference between Elliptic-Curve Diffie-Hellman (ECDH) and standard Diffie-Hellman (DH)?

The key difference between Elliptic-Curve Diffie-Hellman (ECDH) and standard Diffie-Hellman (DH) lies in their mathematical foundations. ECDH employs elliptic curve cryptography, which utilizes the algebraic structure of elliptic curves over finite fields. This approach allows for higher levels of security with smaller key sizes compared to traditional DH, which is based on the difficulty of computing discrete logarithms in a finite field.

This fundamental distinction means that ECDH can achieve equivalent security levels using shorter keys, making it more efficient in terms of performance and resource consumption, which is particularly advantageous in environments with limited processing power.

The other options touch on different aspects of ECDH and DH but do not accurately represent their fundamental differences. For instance, while ECDH is often associated with modern security protocols and can facilitate authentication, stating it provides built-in authentication outright may be misleading as authentication mechanisms typically need to be implemented alongside either method. Understanding the core mathematical differences is essential for differentiating between ECDH and DH in cybersecurity architecture and engineering contexts.