Question: In a Generic Authentication Architecture (GAA) context, what security protocol is mandated for the User Equipment (UE)-Network Application Function (NAF) interface (Ua), allowing the NAF to specify a key for securing this link?
Option 1: TLS (Transport Layer Security)
Option 2: IPsec (Internet Protocol Security)
Option 3: PGP (Pretty Good Privacy)
Option 4: DTLS (Datagram Transport Layer Security)
Explanation: DTLS is the correct answer because, unlike TLS which requires a persistent connection, DTLS is designed to work with datagram-oriented transport protocols like UDP, making it more suitable for the potentially variable connectivity conditions of UE-NAF communications. The requirement for DTLS support at the NAF for the Ua reference point ensures secure communication between the UE and NAF, accommodating the need for intermittent or unreliable connections. This aligns with the GAA's goal of providing a flexible yet secure authentication framework.