Section: A.1 KDF interface and input parameter construction A.1.1 General
Content: All key derivations (including input parameter encoding) for 5GC shall be performed using the key derivation function (KDF) specified in Annex B.2.0 of TS 33.220[ Generic Authentication Architecture (GAA); Generic Bootstrapping Architecture (GBA) ]  [28]. This clause specifies how to construct the input string, S, and the input key, KEY, for each distinct use of the KDF. Note that "KEY" is denoted "Key" in TS 33.220[ Generic Authentication Architecture (GAA); Generic Bootstrapping Architecture (GBA) ]  [28].