Elliptic Curve Diffie-Hellman

Elliptic Curve Diffie-Hellman (ECDH) is a key agreement protocol that allows two parties to establish a shared secret over an insecure channel using elliptic curve cryptography. It is a variant of the classic Diffie-Hellman protocol but leverages the mathematical properties of elliptic curves to provide equivalent security with smaller key sizes, making it more efficient. ECDH is widely used in secure communication protocols like TLS, SSH, and VPNs to enable encrypted data exchange.

Also known as: ECDH, Elliptic Curve Diffie Hellman, EC Diffie-Hellman, Elliptic Curve DH, ECDHE

Why learn Elliptic Curve Diffie-Hellman?

Developers should learn and use ECDH when implementing secure key exchange in applications that require confidentiality, such as encrypted messaging, secure file transfers, or real-time communication systems. It is particularly valuable in resource-constrained environments like mobile devices or IoT systems due to its efficiency with smaller keys, and it is essential for modern cryptographic standards like TLS 1.3, which often defaults to ECDH-based cipher suites for enhanced security.

Learning Resources

• docs: NIST Special Publication 800-56A: Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography
• course: Cryptography I by Stanford University (Coursera)
• tutorial: Elliptic Curve Cryptography: a gentle introduction
• video: ECDH Key Exchange Explained (YouTube)
• book: Understanding Cryptography by Christof Paar and Jan Pelzl