Methods and systems are described herein for performing attribute authentication for use by a relying party in providing access to a resource as requested by a user. Attribute authentication may be performed entirely by a single identity service provider, or by multiple identity service providers each authenticating a subset of a plurality of user attributes, such as name, address, phone, email, and the like. Each attribute may be authenticated with a level of assurance. Levels of assurance may vary from attribute to attribute. Different levels of assurance may be required for different attributes before the relying party may grant access to the user-desired resource. An authentication broker may act as a registry or broker of identity service providers, and may store information usable by relying parties to establish a trust relationship with a particular identity service provider on demand, as needed by a relying party.