Question: In 3GPP security protocols, what is the primary purpose of the cryptographic functions f3 and f4 in the authentication and key agreement mechanism?
Option 1: Derivation of keys for user authentication and network authentication respectively.
Option 2: Generation of random challenges for initial access and re-synchronization.
Option 3: Ensuring anonymity in both normal operation and re-synchronization phases.
Option 4: Derivation of cipher keys and integrity keys from the master key.
Explanation: In the context of 3GPP security, specifically within authentication and key agreement mechanisms, f3 (cipher key derivation function) and f4 (integrity key derivation function) are crucial for generating distinct types of cryptographic keys. The cipher key is used for encrypting data to ensure confidentiality, while the integrity key is used for ensuring the authenticity and integrity of the data being transmitted. Thus, these functions are pivotal in deriving keys that protect both the secrecy and the integrity of communications in telecom networks.