A.5 HRES* and HXRES* derivation function

33.5013GPPRelease 18Security architecture and procedures for 5G SystemTS

When deriving HRES* from RES* in the SEAF and when deriving HXRES* from XRES* in the AUSF the following parameters shall be used to form the input S to the SHA-256 hashing algorithm:

– P0 = RAND,

– P1 = RES* or XRES*,

The input S shall be equal to the concatenation P0||P1 of the P0 and P1.

The H(X)RES* is identified with the 128 least significant bits of the output of the SHA-256 function.