Question: What is the primary method by which 5GSM messages are security protected in the NAS protocol?
Option 1: Direct integrity protection and ciphering of 5GSM messages.
Option 2: Piggybacking on security-protected 5GMM messages, such as UL NAS TRANSPORT and DL NAS TRANSPORT messages.
Option 3: Using a separate security protocol specifically designed for 5GSM messages.
Option 4: Relying solely on the security measures implemented at the UDM.
Explanation: According to the principles outlined in the NAS protocol, 5GSM messages are indirectly security protected by being piggybacked on the security-protected 5GMM messages. This approach leverages the existing security mechanisms applied to 5GMM messages to provide protection for 5GSM messages as well.