Question: What is the requirement for protecting long-term keys used for authentication and security association setup purposes in a 5G system?
Option 1: They should be encrypted when transmitted over the network.
Option 2: They can be stored in plaintext in the UDR.
Option 3: They should be protected from physical attacks, but can leave the secure environment of the UDM/ARPF for specific purposes.
Option 4: They shall be protected from physical attacks and shall never leave the secure environment of the UDM/ARPF unprotected.
Explanation: The correct answer is Option 4 because it aligns with the generic requirement stated in the text, which emphasizes that long-term keys used for authentication and security association setup purposes must be protected from physical attacks and should never leave the secure environment of the UDM/ARPF unprotected. This ensures a high level of security for these sensitive keys within the 5G system architecture.