scope:

The present document specifies a generic push layer that makes use of the GBA Push Function as specified in TS 33.223 [3]. The GPL specification includes a message format, cipher suites and processing model. GPL assumes that keys and other SA parameters have been preinstalled in the Push-NAF and UE in the form of a NAF SA. GPL is a protection protocol that can be applied in a unidirectional fashion.

The rationale for GPL is that having each application specify its own security mechanisms would for obvious reasons lead to duplication of work, specifications and implementations. Using a generic secure push layer avoids these problems. A generic secure push layer may also relieve the applications using the service of having to be aware of inner working of the security layer. As an analogy, TS 33.222 [4] can be mentioned, which provides a generic security layer for HTTP based applications.