Developed by Whitfield Diffie and Martin Hellman in 1976, the DH is an algorithm upon which a number of secure connectivity protocols on the Internet are built. It is now celebrating more than 25 years of use. DH is a means of securely transmitting a secret to be shared between two parties over an untrusted network in real time. A shared secret is critical for two parties who likely have not communicated before; it is used so that they are able to encrypt communications. Today, DH is used by protocols such as Internet Protocol Security (IPSec), Secure Shell (SSH), and Secure Sockets Layer (SSL).

See Also: Algorithm; Internet; Internet Protocol Security (IPSec); Secure Sockets Layer (SSL); Shell; SSH.