What is the purpose of the Bootstrapping Server Function (BSF)?
To authenticate the UE and the Network Application Function (NAF) using the AKA protocol.
To keep a list assigning NAFs to NAF groups.
To acquire the GBA User Security Settings (GUSS) from the HSS.
To restrict the applicability of the key material to a specific NAF.
To generate key material for the UE-NAF communication.