Cryptographic protocol

A cryptographic protocol is a way to securely exchange data over a computer network. The data that is exchanged is encrypted. In general, these protocols consist of a way to exchange encryption keys, The data is then encrypted using symmetric or asymmetric cryptography. Symmetric cryptography is used more often. 
Common protocols include: 
A cryptographic protocol usually has at least some of these features: 
The term "cryptographic protocol" is used in different ways. For example, cryptographic "application" protocols often use one or more underlying Key-agreement protocols which are also sometimes themselves referred to as "cryptographic protocols", like the Secure Sockets Layer (SSL) which uses what is known as the Diffie-Hellman key exchange, Diffie-Hellman may be seen as a complete "cryptographic protocol" in itself for other applications.