Section: A.4 RES* and XRES* derivation function
Content: When deriving RES* from RES, RAND, and serving network name in the UE and when deriving XRES* from XRES, RAND, and the serving network name in the ARPF, the following parameters shall be used to form the input S to the KDF. - FC = 0x6B, - P0 = serving network name, - L0 = length of the serving network name (variable length as specified in 24.501 [35]), - P1 = RAND, - L1 = length of RAND (i.e. 0x00 0x10), - P2 = RES or XRES, - L2 = length RES or XRES (i.e. variable length between 0x00 0x04 and 0x00 0x10). The input key KEY shall be equal to the concatenation CK || IK of CK and IK. The serving network name shall be constructed as specified in clause 6.1.1.4. The (X)RES* is identified with the 128 least significant bits of the output of the KDF.