Question: What is the process to derive the salt value for AES-GMAC with a 128-bit key in IPsec ESP, according to security standards?
Option 1: The salt value is derived directly from CKIM without using a Key Derivation Function (KDF).
Option 2: The input Key to the KDF function is IKIM alone, with inputs S including FC=0x58 and P0="AES_GMAC_SALT".
Option 3: The salt value consists of the 256 most significant bits of the 512 bits of the KDF output, using CKIM||IKIM as the input Key.
Option 4: The salt value is derived using a KDF with the input Key being the concatenation of CKIM and IKIM (CKIM||IKIM), and inputs S including FC=0x58, P0="AES_GMAC_SALT", taking the 32 least significant bits of the 256-bit KDF output.
Explanation: This option correctly outlines the process for deriving the salt value for AES-GMAC with a 128-bit key as specified in IPsec ESP security standards, ensuring secure key management in telecommunications networks by accurately detailing the use of a KDF, input Key composition, specific parameters, and salt value selection.