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A security protocol (or cryptographic protocol) is an abstract or concrete protocol that performs a security-related function and applies cryptographic methods.
Cryptographic protocols are widely used for secure application-level data transport. A cryptographic protocol usually incorporates at least some of these aspects:
- Key agreement or establishment
- Entity authentication
- Symmetric encryption and message authentication material construction
- Secured application-level data transport
- Non-repudiation methods
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.
There are other types of cryptographic protocols as well, and even the term itself has various different readings; Cryptographic application protocols often use one or more underlying key agreement methods, which are also sometimes themselves referred to as "cryptographic protocols". For instance, TLS employs what is known as the Diffie-Hellman key exchange, which although it is only a part of TLS per se, Diffie-Hellman may be seen as a complete cryptographic protocol in itself for other applications.
Cryptographic protocols can sometimes be verified formally on an abstract level.
See also
External links
"Cryptographic protocol"