sha256-kdf.c File Reference

HMAC-SHA256 KDF (RFC 5295) More...

#include "includes.h"
#include "common.h"
#include "sha256.h"

Functions
int	hmac_sha256_kdf (const u8 *secret, size_t secret_len, const char *label, const u8 *seed, size_t seed_len, u8 *out, size_t outlen)
	HMAC-SHA256 based KDF (RFC 5295) More...

Detailed Description

HMAC-SHA256 KDF (RFC 5295)

Function Documentation

int hmac_sha256_kdf	(	const u8 *	secret,
		size_t	secret_len,
		const char *	label,
		const u8 *	seed,
		size_t	seed_len,
		u8 *	out,
		size_t	outlen
	)

HMAC-SHA256 based KDF (RFC 5295)

Parameters

secret	Key for KDF
secret_len	Length of the key in bytes
label	A unique label for each purpose of the KDF
seed	Seed value to bind into the key
seed_len	Length of the seed
out	Buffer for the generated pseudo-random key
outlen	Number of bytes of key to generate

Returns

0 on success, -1 on failure.

This function is used to derive new, cryptographically separate keys from a given key in ERP. This KDF is defined in RFC 5295, Chapter 3.1.2.