romulus-hkdf.h File Reference

HMAC-based key derivation function based on Romulus-HMAC. More...

#include <stddef.h>

Go to the source code of this file.

Data Structures
struct	romulus_hkdf_state_t
	State for incremental generation of key material from Romulus-HKDF. More...

Macros
#define	ROMULUS_HKDF_OUTPUT_SIZE   32
	Default output block size for Romulus-HKDF. Key material is generated in blocks of this size.

Functions
int	romulus_hkdf (unsigned char *out, size_t outlen, const unsigned char *key, size_t keylen, const unsigned char *salt, size_t saltlen, const unsigned char *info, size_t infolen)
	Derives key material using Romulus-HKDF. More...
void	romulus_hkdf_extract (romulus_hkdf_state_t *state, const unsigned char *key, size_t keylen, const unsigned char *salt, size_t saltlen)
	Extracts entropy from a key and salt for Romulus-HKDF. More...
int	romulus_hkdf_expand (romulus_hkdf_state_t *state, const unsigned char *info, size_t infolen, unsigned char *out, size_t outlen)
	Expands key material using a Romulus-HKDF state. More...
void	romulus_hkdf_free (romulus_hkdf_state_t *state)
	Frees all sensitive material in a Romulus-HKDF state. More...

Detailed Description

HMAC-based key derivation function based on Romulus-HMAC.

Reference: https://tools.ietf.org/html/rfc5869

Function Documentation

int romulus_hkdf	(	unsigned char *	out,
		size_t	outlen,
		const unsigned char *	key,
		size_t	keylen,
		const unsigned char *	salt,
		size_t	saltlen,
		const unsigned char *	info,
		size_t	infolen
	)

Derives key material using Romulus-HKDF.

Parameters

out	Points to the output buffer to receive the key material.
outlen	Number of bytes of key material to generate, maximum of ROMULUS_HKDF_OUTPUT_SIZE * 255 bytes.
key	Points to the bytes of the key.
keylen	Number of bytes in the key.
salt	Points to the bytes of the salt.
saltlen	Number of bytes in the salt.
info	Points to the bytes of the informational data.
infolen	Number of bytes in the informational data.

Returns

Zero on success or -1 if outlen is out of range.

See Also

romulus_hkdf_extract(), romulus_hkdf_expand()

int romulus_hkdf_expand	(	romulus_hkdf_state_t *	state,
		const unsigned char *	info,
		size_t	infolen,
		unsigned char *	out,
		size_t	outlen
	)

Expands key material using a Romulus-HKDF state.

Parameters

state	HKDF state to use to expand key material.
info	Points to the bytes of the informational data.
infolen	Number of bytes in the informational data.
out	Points to the output buffer to receive the key material.
outlen	Number of bytes of key material to generate.

Returns

Zero on success or -1 if too many bytes have been generated so far. There is a limit of ROMULUS_HKDF_OUTPUT_SIZE * 255 bytes.

void romulus_hkdf_extract	(	romulus_hkdf_state_t *	state,
		const unsigned char *	key,
		size_t	keylen,
		const unsigned char *	salt,
		size_t	saltlen
	)

Extracts entropy from a key and salt for Romulus-HKDF.

Parameters

state	HKDF state to be initialized.
key	Points to the bytes of the key.
keylen	Number of bytes in the key.
salt	Points to the bytes of the salt.
saltlen	Number of bytes in the salt.

See Also

romulus_hkdf_expand(), romulus_hkdf()

void romulus_hkdf_free

(

romulus_hkdf_state_t *

state

)

Frees all sensitive material in a Romulus-HKDF state.

Parameters

state

Points to the HKDF state.