A
security protocol (
cryptographic protocol or
encryption protocol) is an abstract or concrete
protocol that performs a
security-related function and applies
cryptographic methods.
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 transport. A cryptographic protocol usually incorporates at least some of these aspects
For example, Transport Layer Security (TLS) is a cryptographic protocol that is used to secure web (HTTP) connections. It has an entity authentication mechanism, based on the X.509 system; a key setup phase, where a symmetric encryption key is formed by employing public-key cryptography; and an application-level data transport function. These three aspects have important interconnections. Standard TLS does not have non-repudiation support.
