Definition
Diffie-Hellman is a cryptographic method that allows two parties to establish a shared secret key over an insecure communication channel without prior knowledge of each other. It works by having each party generate a private key and a public key, then exchanging their public keys to compute a shared secret. This shared secret can then be used to encrypt subsequent communications, ensuring confidentiality and integrity. For example, it is fundamental to the security of HTTPS connections, enabling secure web browsing. Unlike encryption algorithms that directly secure data, Diffie-Hellman is used solely for key agreement. This concept is frequently tested on cybersecurity certifications like CompTIA Security+ and CISSP.