What is an attribute provider (AP)?

An attribute provider is an entity, usually a register or directory, that runs an attribute service to maintain attributes and an attribute assertion service to issue attribute assertions.

Where an IdP answers "who is this?", an attribute provider answers "what is true about this subject?", for instance a residents' register attesting an address. Synonyms: attribute authority, data supplier, information supplier, OIDC claims provider.

Go deeper:

• Attribute provider (NIST glossary) — an identity API that serves attributes without asserting that the subject is present.