Content for TS 33.533 Word version: 18.3.0

A.1 KDF interface and input parameter construction A.1.1 General A.1.2 FC value allocations A.2 Calculation of KSLP A.3 Calculation of SLPTK A.4 Calculation of keys from SLPTK

A (Normative) Key derivation functions p. 21

A.1 KDF interface and input parameter construction p. 21

A.1.1 General p. 21

This Annex specifies the use of the Key Derivation Function (KDF) specified in TS 33.220 for the present document. This annex specifies how to construct the input string, S, and the input key KEY to the KDF. Note that "KEY" is denoted "Key" in TS 33.220.

A.1.2 FC value allocations p. 21

The FC number space used is allocated as per clause B.2.2 of TS 33.220.

A.2 Calculation of KSLP p. 21

When calculating KSLP from SLPK, the following parameters shall be used to form the input S to the KDF specified in Annex B of TS 33.220:

FC = 0x8C
P0 = Ranging/SL Positioning Application Identifier
L0 = length of Ranging/SL Positioning Application Identifier (i.e. 0x00 0x03)
P1 = KSLP nonce 1
L1 = length of KSLP nonce 1 (i.e. 0x00 0x10)
P2 = KSLP nonce 2
L2 = length of KSLP nonce 2 (i.e. 0x00 0x10)

The input key to the KDF is the 256-bit SLPK.

A.3 Calculation of SLPTK p. 21

When calculating a SLPTK from SLPGK, the following parameters shall be used to form the input S to the KDF that is specified in Annex B of TS 33.220:

FC = 0x8D
P0 = Group Member Identity
L0 = length of Group Member Identity
P1 = SLPTK Identity
L1 = length of SLPTK Identity

The input key shall be the 256-bit SLPGK.

A.4 Calculation of keys from SLPTK p. 22

When calculating a SLPIK or SLPEK from SLPTK, the following parameters shall be used to form the input S to the KDF that is specified in Annex B of TS 33.220:

FC = 0x8E
P0 = 0x00 if SLPEK is being derived or 0x01 if SLPIK is being derived
L0 = length of P0 (i.e. 0x00 0x01)
P1 = algorithm identity
L1 = length of algorithm identity (i.e. 0x00 0x01)

The algorithm identity shall be set as described in TS 33.501.

The input key shall be the 256-bit SLPTK.

For an algorithm key of length n bits, where n is less or equal to 256, the n least significant bits of the 256 bits of the KDF output shall be used as the algorithm key.