partiallyauthenticated

Partiallyauthenticated is a term used in information security to describe a property of a communication or data element in which only a subset of its components are protected against tampering by cryptographic authentication. In such scenarios, some parts, such as headers or metadata, may be authenticated, while other parts, such as the message body, are not guaranteed to be authentic or integral. This contrasts with fully authenticated systems, where the entire message is protected by a MAC or an authenticated encryption mode.

Partial authentication can arise in protocol design for performance reasons, compatibility, or when different parties have different trust requirements. For example, a protocol might attach a MAC to the header fields but omit authentication of the payload to save processing or bandwidth. Alternatively, associated data in an AEAD scheme may authenticate only specific fields, leaving others unprotected.

Security implications: Partially authenticated data remains vulnerable to tampering in unauthenticated components, enabling potential attacks such as header injection, data corruption, or replay attacks if not properly mitigated. To reduce risk, cryptographic designs typically strive for authenticated encryption with associated data that covers all critical parts, or they isolate unauthenticated components to minimal risk paths and apply strong validation at the application layer.

Relation to related terms: Fully authenticated data is protected by an authentication mechanism for all parts; MACs and AEAD schemes provide integrity guarantees. Partially authenticated systems often require careful threat modeling and supplementary controls such as integrity checks, strict input validation, and secure defaults.

See also: authentication, data integrity, message authentication code, authenticated encryption, associated data.