HMAC Keyed Message Digest

Macros
#define	LC_HMAC_CTX_ON_STACK(name, hashname)
	Allocate stack memory for the HMAC context.

Functions
void	lc_hmac_init (struct lc_hmac_ctx *hmac_ctx, const uint8_t *key, size_t keylen)
	Initialize HMAC context.
void	lc_hmac_reinit (struct lc_hmac_ctx *hmac_ctx)
	Re-initialize HMAC context after a hmac_final operation.
void	lc_hmac_update (struct lc_hmac_ctx *hmac_ctx, const uint8_t *in, size_t inlen)
	Update HMAC.
void	lc_hmac_final (struct lc_hmac_ctx *hmac_ctx, uint8_t *mac)
	Calculate HMAC mac.
int	lc_hmac_alloc (const struct lc_hash *hash, struct lc_hmac_ctx **hmac_ctx)
	Allocate HMAC context on heap.
void	lc_hmac_zero_free (struct lc_hmac_ctx *hmac_ctx)
	Zeroize and free HMAC context.
static void	lc_hmac_zero (struct lc_hmac_ctx *hmac_ctx)
	Zeroize HMAC context allocated with either HMAC_CTX_ON_STACK or hmac_alloc.
static size_t	lc_hmac_macsize (struct lc_hmac_ctx *hmac_ctx)
	Return the MAC size.
static void	lc_hmac (const struct lc_hash *hash, const uint8_t *key, size_t keylen, const uint8_t *in, size_t inlen, uint8_t *mac)
	Calculate HMAC - one-shot.

Detailed Description

Macro Definition Documentation

LC_HMAC_CTX_ON_STACK

#define LC_HMAC_CTX_ON_STACK	(		name,
			hashname )

Value:

        _Pragma("GCC diagnostic push")                                              \
                _Pragma("GCC diagnostic ignored \"-Wvla\"") _Pragma(                \
                        "GCC diagnostic ignored \"-Wdeclaration-after-statement\"") \
                        LC_ALIGNED_BUFFER(name##_ctx_buf,                           \
                                          LC_HMAC_CTX_SIZE(hashname),               \
                                          LC_HASH_COMMON_ALIGNMENT);                \
        struct lc_hmac_ctx *name = (struct lc_hmac_ctx *)name##_ctx_buf;            \
        LC_HMAC_SET_CTX(name, hashname);                                            \
        lc_hmac_zero(name);                                                         \
        _Pragma("GCC diagnostic pop")

Allocate stack memory for the HMAC context.

Parameters

[in]	name	Name of the stack variable
[in]	hashname	Pointer of type struct hash referencing the hash implementation to be used

Definition at line 165 of file lc_hmac.h.

Function Documentation

lc_hmac()

static void lc_hmac ( const struct lc_hash * hash, const uint8_t * key, size_t keylen, const uint8_t * in, size_t inlen, uint8_t * mac )

inlinestatic

Calculate HMAC - one-shot.

Parameters

[in]	hash	Reference to hash implementation to be used to perform HMAC calculation with.
[in]	key	MAC key of arbitrary size
[in]	keylen	Size of the MAC key
[in]	in	Buffer holding the data whose MAC shall be calculated
[in]	inlen	Length of the input buffer
[out]	mac	Buffer with at least the size of the message digest.

The HMAC calculation operates entirely on the stack.

Definition at line 206 of file lc_hmac.h.

lc_hmac_alloc()

int lc_hmac_alloc	(	const struct lc_hash *	hash,
		struct lc_hmac_ctx **	hmac_ctx )

Allocate HMAC context on heap.

Parameters

[in]	hash	Reference to hash implementation to be used to perform HMAC calculation with.
[out]	hmac_ctx	Allocated HMAC context

Returns

0 on success, < 0 on error

lc_hmac_final()

void lc_hmac_final	(	struct lc_hmac_ctx *	hmac_ctx,
		uint8_t *	mac )

Calculate HMAC mac.

If the cipher handle shall be used for a new HMAC operation with the same key after this call, you MUST re-initialize the handle with hmac_reinit.

Parameters

[in]	hmac_ctx	Reference to hmac context implementation to be used to perform HMAC calculation with.
[out]	mac	Buffer with at least the size of the message digest that is returned by hmac_macsize.

lc_hmac_init()

void lc_hmac_init	(	struct lc_hmac_ctx *	hmac_ctx,
		const uint8_t *	key,
		size_t	keylen )

Initialize HMAC context.

Parameters

[in]	hmac_ctx	Reference to hmac context implementation to be used to perform HMAC calculation with.
[in]	key	MAC key of arbitrary size
[in]	keylen	Size of the MAC key

The caller must provide an allocated hmac_ctx. This can be achieved by using HMAC_CTX_ON_STACK or by using hmac_alloc.

lc_hmac_macsize()

static size_t lc_hmac_macsize ( struct lc_hmac_ctx * hmac_ctx )

inlinestatic

Return the MAC size.

Parameters

[in]

hmac_ctx

HMAC context to be zeroized

Returns

MAC size

Definition at line 185 of file lc_hmac.h.

lc_hmac_reinit()

void lc_hmac_reinit

(

struct lc_hmac_ctx *

hmac_ctx

)

Re-initialize HMAC context after a hmac_final operation.

This operation allows the HMAC context to be used again with the same key set during hmac_init.

Parameters

[in]

hmac_ctx

Reference to hmac context implementation to be used to perform HMAC calculation with.

lc_hmac_update()

void lc_hmac_update	(	struct lc_hmac_ctx *	hmac_ctx,
		const uint8_t *	in,
		size_t	inlen )

Update HMAC.

Parameters

[in]	hmac_ctx	Reference to hmac context implementation to be used to perform HMAC calculation with.
[in]	in	Buffer holding the data whose MAC shall be calculated
[in]	inlen	Length of the input buffer

lc_hmac_zero()

static void lc_hmac_zero ( struct lc_hmac_ctx * hmac_ctx )

inlinestatic

Zeroize HMAC context allocated with either HMAC_CTX_ON_STACK or hmac_alloc.

Parameters

[in]

hmac_ctx

HMAC context to be zeroized

Definition at line 148 of file lc_hmac.h.

lc_hmac_zero_free()

void lc_hmac_zero_free

(

struct lc_hmac_ctx *

hmac_ctx

)

Zeroize and free HMAC context.

Parameters

[in]

hmac_ctx

HMAC context to be zeroized and freed