3.4. Implementation Considerations

3.4. Implementation Considerations

An entity can take on multiple RATS roles (e.g., Attester, Verifier, Relying Party, etc.) at the same time. Multiple entities can cooperate to implement a single RATS role as well. In essence, the combination of roles and entities can be arbitrary. For example, in the composite device scenario, the entity inside the lead Attester can also take on the role of a Verifier and the outer entity of Verifier can take on the role of a Relying Party. After collecting the Evidence of other Attesters, this inside Verifier uses Endorsements and appraisal policies (obtained the same way as by any other Verifier) as part of the appraisal procedures that generate Attestation Results. The inside Verifier then conveys the Attestation Results of other Attesters to the outside Verifier, whether in the same conveyance protocol as part of the Evidence or not.

As explained in Section 4, there are a variety of roles in the RATS architecture; they are defined by a unique combination of artifacts they produce and consume. Conversely, artifacts are also defined by the roles that produce or consume them. To produce an artifact means that a given role introduces it into the RATS architecture. To consume an artifact means that a given role has responsibility for processing it in the RATS architecture. Roles also have the ability to perform additional actions, such as caching or forwarding artifacts as opaque data. As depicted in Section 5, these additional actions can be performed by several roles.