A number of applications share a need for mutual authentication between a client (i.e. the UE ) and an application server before further communication can take place. Examples include (but are not limited to) communication between a client and a presence server (possibly via an authentication proxy), communication with a PKI portal where a client requests a digital certificate, communication with a Mobile Broadcast / Multicast Service (MBMS) content server, a BM-SC, etc.
Since a lot of applications share this common need for a peer authentication mechanism, it has been considered useful to specify a Generic Authentication Architecture (GAA). This GAA describes a generic architecture for peer
authentication that can a priori serve for any (present and future) application.
This TR can be considered as a framework document for the generic authentication architecture. GBA, HTTPS and the Authentication Proxy (AP), and Certificates are the basic building blocks of the GAA in 3GPP Release 6 and they are specified each in a separate TS. Later on, many additions were made to accommodate specific needs for various use cases.
How the different GAA and GBA related specifications and technical reports fit together in GAA is explained in this document.