Section: 6.3.7 Length of authentication parameters
Content: The authentication key (K) shall have a length of 128 bits or 256 bits. NOTE: Examples of algorithm set for 3GPP authentication and key agreement functions allow either an authentication key K with only a length of 128 bits, or an authentication key K with a length of 128 bits or 256 bits. Depending on the chosen algorithm set, the operator may have the choice of the length of the authentication key K (128 bits or 256 bits). The random challenge () shall have a length of 128 bits. Sequence numbers (SQN) shall have a length of 48 bits. The anonymity key (AK) shall have a length of 48 bits. The authentication management field (AMF) shall have a length of 16 bits. The message authentication codes MAC in AUTN and MAC-S in AUTS shall have a length of 64 bits. The cipher key (CK) shall have a length of 128 bits. The integrity key (IK) shall have a length of 128 bits. The authentication response (RES) shall have a variable length of 4-16 octets.