.TH LIBSHA2_HMAC_INIT 3 2019-02-10 libsha2
.SH NAME
libsha2_hmac_init \- Initialises hashing with an HMAC-SHA-2 algorithm
.SH SYNOPSIS
.nf
#include <libsha2.h>

enum libsha2_algorithm {
	LIBSHA2_224,     /* SHA-224     */
	LIBSHA2_256,     /* SHA-256     */
	LIBSHA2_384,     /* SHA-384     */
	LIBSHA2_512,     /* SHA-512     */
	LIBSHA2_512_224, /* SHA-512/224 */
	LIBSHA2_512_256  /* SHA-512/256 */
};

int libsha2_hmac_init(struct libsha2_hmac_state *restrict \fIstate\fP, enum libsha2_algorithm \fIalgorithm\fP,
                      const void *restrict \fIkey\fP, size_t \fIkeylen\fP);
.fi
.PP
Link with
.IR \-lsha2 .
.SH DESCRIPTION
The
.BR libsha2_hmac_init ()
function stores the selected
.I algorithm
in
.I state
and initialises
.I state
with the first
.I keylen
bits of
.I key
as the key.
.SH RETURN VALUE
The
.BR libsha2_hmac_init ()
function returns 0 upon successful completion,
otherwise -1 is returned and
.I errno
is set appropriately.
.SH ERRORS
The
.BR libsha2_hmac_init ()
function will fail if:
.TP
.B EINVAL
.I algorithm
is not a valid
.B enum libsha2_algorithm
value.
.SH EXAMPLES
None.
.SH APPLICATION USAGE
None.
.SH RATIONALE
None.
.SH FUTURE DIRECTIONS
None.
.SH NOTES
None.
.SH BUGS
None.
.SH SEE ALSO
.BR libsha2_hmac_digest (3),
.BR libsha2_hmac_marshal (3),
.BR libsha2_hmac_unmarshal (3),
.BR libsha2_hmac_update (3)