Question: In ISIM Local Key Establishment security context, what happens if the ISIM cannot find a valid Ks_int_NAF associated with the received NAF_ID?
Option 1: The ISIM generates a new Ks_int_NAF and proceeds with key derivation.
Option 2: The ISIM abandons the function and returns the status word '6A88' (Referenced data not found).
Option 3: The ISIM requests additional authentication from the Terminal to verify NAF_ID.
Option 4: The ISIM uses a default Ks_int_NAF for key derivation.
Explanation: According to the specified security context, if no valid Ks_int_NAF is available when the ISIM attempts to identify it using the received NAF_ID, this scenario is considered a Key Establishment failure. Consequently, the ISIM terminates the operation and returns a specific status word indicating the issue, which in this case is '6A88' for "Referenced data not found". This ensures security by not proceeding with potentially compromised or unidentified key material.