Painless Security Nokia Siemens Networks This document describes a mechanism for establishing trust across a multihop federation within the Application Bridging for Federation Beyond the Web (ABFAB) framework. This document introduces a new entity, the Trust Router. Trust Routers exchange information about the availability of Trust Paths across a multihop federation. They can be queried by a Relying Party to obtain the best Trust Path to reach an Identity Provider. They also provide temporary identities that can be used by a Relying Party to traverse a Trust Path.