Qualities of Trust Relationships
This section describes some common qualities or characteristics of trust relationships. All trust models should exhibit these qualities to be considered viable.
Portability and Interoperability
Portability and interoperability are similar, but with subtle differences. Portability depends on standardized credential types and formats to be used anywhere, and at any time. The use of a standards-defined public key certificate recognized across multiple PKIs is an example of portability.
Interoperability depends on the standardization of protocols for testing credentials. Interoperability relies on applications and systems to implement standardized protocols for credential testing. The use of standards-defined protocols (for example, those from the Liberty Alliance) to perform security functions such as authentication and authorization across multiple platforms is an example of interoperability.
Reliability embraces a closely related aspect of credentials and their evaluation. Credentials and the mechanism that evaluate them must perform consistently, in a repeatable fashion over time.
Assurance is a critical quality of any trust relationship. Relative to trust, assurance is concerned with the preservation of the binding between a unique entity and its credentials. Here, preservation means that a credential continues to be accurately bound with the correct entity to which it is associated.