What is Cryptographic Protocol?

A cryptographic protocol is an abstract or concrete protocol that performs security-related functions and applies cryptographic methods, often as sequences of cryptographic primitives. A protocol describes how the algorithms should be used. A sufficiently detailed protocol includes details about data structures and representations, at which point it can be used to implement multiple, interoperable versions of a program. Cryptographic protocols are widely used for secure application-level data.

Key agreement or establishment

 - Entity authentication

 - Symmetric encryption and message authentication material construction

 - Secured application-level data transport

 - Non-repudiation methods

 - Secret sharing methods

 - Secure multi-party computation

(source: Wikipedia)