Bootstrapping interface (Ub) and network application function interface (Ua); Protocol details
The present document defines stage 3 for the HTTP Digest AKA as specified in RFC 3310 [6] based implementation of Ub interface (UE-BSF), the Disposable-Ks model based implementation of Upa interface (NAF-UE) and the HTTP Digest as specified in RFC 7616 [36] and the PSK TLS based implementation of bootstrapped security association usage over Ua interface (UE-NAF) in Generic Authentication Architecture (GAA) as specified in 3GPP TS 33.220 [1]. The purpose of the Ub interface is to create a security association between UE and BSF for further usage in GAA applications. The purpose of the Upa interface is to provide a push mechanism to created a bootstrapped security association between the UE and NAF for secure communication of pushed messages. The purpose of the Ua interface is to use the so created bootstrapped security association between UE and NAF for secure communication.
The present document also defines stage 3 for the Authentication Proxy usage as specified in 3GPP TS 33.222 [5].
The present document also defines stage 3 for the subscriber certificate enrolment as specified in 3GPP TS 33.221 [4] which is one realization of the Ua interface. The subscriber certificate enrolment uses the HTTP Digest based implementation of bootstrapped security association usage to enrol a subscriber certificate and the delivery of a CA certificate.
The present document also defines stage 3 for TLS using AKMA (Authentication and Key Management for Applications) keys over the Ua* interface (AKMA AF-UE) as described in 3GPP TS 33.535 [38].