Content for TS 33.535 Word version: 18.4.0
A Key derivation functions
A.1 KDF interface and input parameter construction
A.1.1 General
A.1.2 FC value allocations
A.2 KAKMA derivation function
A.3 A-TID derivation function
A.4 KAF derivation function
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A (Normative) Key derivation functions p. 26
A.1 KDF interface and input parameter construction p. 26
A.1.1 General p. 26
All key derivations for AKMA shall be performed using the key derivation function (KDF) specified in Annex B.2.2 of TS 33.220.
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.
A.1.2 FC value allocations p. 26
The FC number space used is controlled by TS 33.220, FC values allocated for the present document are in the range of 0x80 - 0x82.
A.2 KAKMA derivation function p. 26
When deriving a KAKMA from KAUSF, the following parameters shall be used to form the input S to the KDF:
- FC = 0x80;
- P0 = "AKMA";
- L0 = length of "AKMA"; (i.e. 0x00 0x04)
- P1 = SUPI;
- L1 = length of SUPI.
A.3 A-TID derivation function p. 26
When deriving the A-TID from KAUSF, the following parameters shall be used to form the input S to the KDF:
- FC = 0x81;
- P0 = "A-TID";
- L0 = length of "A-TID"; (i.e. 0x00 0x05)
- P1 = SUPI;
- L1 = length of SUPI.
A.4 KAF derivation function p. 27
When deriving a KAF from KAKMA, the following parameters shall be used to form the input S to the KDF:
- FC = 0x82;
- P0 =AF_ID;
- L0 = length of AF_ID
