Section: 5.9.2.3 NEF security requirements
Content: The Network Exposure Function (NEF) supports external exposure of capabilities of Network Functions to Application Functions, which interact with the relevant Network Functions via the NEF. The interface between the NEF and the Application Function shall fulfil the following requirements: - Integrity protection, replay protection and confidentiality protection for communication between the NEF and Application Function shall be supported. - Mutual authentication between the NEF and Application Function shall be supported. - Internal 5G Core information such as DNN, S-NSSAI etc., shall not be sent outside the 3GPP operator domain. - SUPI shall not be sent outside the 3GPP operator domain by NEF. The NEF shall be able to determine whether the Application Function is authorized to interact with the relevant Network Functions..