A security protocol is a defined sequence of message exchanges and cryptographic operations that lets parties achieve security goals such as confidentiality, integrity, authentication or key establishment over an untrusted channel. Protocols specify message formats, ordering, cryptographic primitives and state transitions, and are designed to resist defined adversaries. Examples include TLS for transport security and authentication protocols for identity verification.
Overview
- Security protocols formalise how parties interact to attain trust properties despite adversaries who may eavesdrop, replay or tamper with traffic. Correctness depends both on sound cryptographic primitives and on careful protocol design, since subtle ordering or state flaws can defeat strong cryptography. Formal verification is increasingly used to prove protocol guarantees.
Mechanisms
- Defined message formats, ordering and state machines.
- Cryptographic primitives for confidentiality, integrity and authentication.
- Key establishment and session management.
- Replay, downgrade and man-in-the-middle resistance.
- Formal analysis under an explicit adversary model.
Applications
- Securing web and API traffic via TLS.
- Authentication and single sign-on flows.
- Federated identity assertions and token exchange.
- Secure messaging and key agreement.