HKDF_expand

Computes the output keying material from input pseudorandom key (PRK), info, and hash method per the HKDF standard.

Syntax

IppStatus ippsHKDF_expand(const Ipp8u* prk, int prkLen, Ipp8u* okm, int okmLen, const Ipp8u* info, int infoLen, const IppsHashMethod*pMethod);

Include Files

ippcp.h

Parameters

prk	Pointer to the input pseudorandom key that was generated by HKDF_extract function call.
prkLen	Length of the input key in bytes.
okm	Pointer to the output keying material.
okmLen	Length of needed output keying material in bytes.
info	Pointer to the info message.
infoLen	Length of the info message in bytes.
pMethod	Pointer to the hash method context.

Description

The function computes the output keying material as a part of the Hashed Message Authentication Code (HMAC)-based key derivation function (HKDF) for HKDF-expand as specified in RFC 5869. The combination of functions ippsHKDF_extract() & ippsHKDF_expand() perform the equivalent combined function ippsHKDF().

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or warning.
ippStsNullPtrErr	Indicates an error condition if any of the specified pointers is NULL.
ippStsLengthErr	Indicates an error condition if okm_len <= 0, okmLen > 255 * hashLen, or infoLen > MAX_HKDF_INFO_SIZE where MAX_HKDF_HASH_SIZE is the maximum hash size in library.
ippsStsNotSupportedModeErr	Indicates hash method is not supported