Question: In a 3GPP Network Domain Security (NDS) context using JSON Web Signature (JWS) as per RFC 7515, what is the mandatory requirement for the "alg" parameter in JWS-supported entities?
Option 1: The "alg" parameter must support both ES256 and RS256 algorithms.
Option 2: The "none" alg parameter is optionally supported for specific use cases.
Option 3: The "alg" parameter can be any of the algorithms listed in RFC 7515, with no specific requirement.
Option 4: The "alg" parameter shall specifically support ES256 (ECDSA using P-256 and SHA-256) and not support "none".
Explanation: This is because, according to the specified restrictions and extensions for JWS in the context of Network Domain Security, entities must support the ES256 algorithm (which utilizes ECDSA with P-256 and SHA-256) for the "alg" parameter. Additionally, it explicitly states that the "none" alg parameter shall not be supported, ensuring a baseline security level across all implementations.