What is an attribute assertion (Attributbestätigung)?

An attribute assertion is the confirmation of an attribute's value for a subject by an attribute provider, an IdP or an issuer; it is often issued together with the authentication assertion after a successful authentication.

Examples across protocols: the SAML 2.0 attribute assertion, the claims in an OIDC ID token, and the claims in a verifiable credential in SSI. Synonyms: attribute assertion, Attributwertbestätigung.

Go deeper:

• NIST SP 800-63C-4 Federation and Assertions — how assertions carry authentication and attribute statements from an IdP to a relying party, including brokered federation.