ThiS TS specifies a generic push layer that makes use of the GBA Push Function as specified in TS 33.223
. 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
can be mentioned, which provides a generic security layer
for HTTP based applications.