Protocol

Synonyms

Cryptographic protocol

Definition

In the context of cryptography, “protocol” is a shorthand for “cryptographic protocol.” A cryptographic protocol is a distributed algorithm describing precisely the interactions of two or more entities to achieve certain security objectives. The entities interact with each other by exchanging messages over private and/or public communication channels.

Important classes of protocols are: key exchange protocols or key establishment protocols, challenge–response protocols, identification verification protocols, and zero-knowledge protocols. A more practical example is the Secure Socket Layer (SSL) protocol for establishing a secure communication link between two entities, a client and a server.

Cryptographic protocols are often used as building blocks for constructing cryptographic schemes (or systems). In general, a cryptographic scheme may be composed of several cryptographic algorithms and/or cryptographic protocols.