Question: What is the primary implication of using the null-scheme for SUCI generation in a 5G system?
Option 1: It ensures that newly generated SUCIs are always fresh to maintain unlinkability.
Option 2: It enables encryption and decryption processes to be skipped, improving performance.
Option 3: It provides no privacy protection and makes it feasible for an over-the-air attacker to link SUCIs together.
Option 4: It guarantees that the SUPI is concealed within the SUCI.
Explanation: The null-scheme does not conceal the SUPI, which means that unlinkability cannot be guaranteed. This makes it possible for an over-the-air attacker to link different SUCIs together, compromising user privacy.