.\" Copyright (c) 2019 Yubico AB. All rights reserved.
.\" Use of this source code is governed by a BSD-style
.\" license that can be found in the LICENSE file.
.\"
.Dd $Mdocdate: June 28 2019 $
.Dt FIDO_CREDMAN_METADATA_NEW 3
.Os
.Sh NAME
.Nm fido_credman_metadata_new ,
.Nm fido_credman_rk_new ,
.Nm fido_credman_rp_new ,
.Nm fido_credman_metadata_free ,
.Nm fido_credman_rk_free ,
.Nm fido_credman_rp_free ,
.Nm fido_credman_rk_existing ,
.Nm fido_credman_rk_remaining ,
.Nm fido_credman_rk ,
.Nm fido_credman_rk_count ,
.Nm fido_credman_rp_id ,
.Nm fido_credman_rp_name ,
.Nm fido_credman_rp_count ,
.Nm fido_credman_rp_id_hash_ptr ,
.Nm fido_credman_rp_id_hash_len ,
.Nm fido_credman_get_dev_metadata ,
.Nm fido_credman_get_dev_rk ,
.Nm fido_credman_del_dev_rk ,
.Nm fido_credman_get_dev_rp
.Nd FIDO 2 credential management API
.Sh SYNOPSIS
.In fido.h
.In fido/credman.h
.Ft fido_credman_metadata_t *
.Fn fido_credman_metadata_new "void"
.Ft fido_credman_rk_t *
.Fn fido_credman_rk_new "void"
.Ft fido_credman_rp_t *
.Fn fido_credman_rp_new "void"
.Ft void
.Fn fido_credman_metadata_free "fido_credman_metadata_t **metadata_p"
.Ft void
.Fn fido_credman_rk_free "fido_credman_rk_t **rk_p"
.Ft void
.Fn fido_credman_rp_free "fido_credman_rp_t **rp_p"
.Ft uint64_t
.Fn fido_credman_rk_existing "const fido_credman_metadata_t *metadata"
.Ft uint64_t
.Fn fido_credman_rk_remaining "const fido_credman_metadata_t *metadata"
.Ft const fido_cred_t *
.Fn fido_credman_rk "const fido_credman_rk_t *rk" "size_t idx"
.Ft size_t
.Fn fido_credman_rk_count "const fido_credman_rk_t *rk"
.Ft const char *
.Fn fido_credman_rp_id "const fido_credman_rp_t *rp" "size_t idx"
.Ft const char *
.Fn fido_credman_rp_name "const fido_credman_rp_t *rp" "size_t idx"
.Ft size_t
.Fn fido_credman_rp_count "const fido_credman_rp_t *rp"
.Ft const unsigned char *
.Fn fido_credman_rp_id_hash_ptr "const fido_credman_rp_t *rp" "size_t idx"
.Ft size_t
.Fn fido_credman_rp_id_hash_len "const fido_credman_rp_t *" "size_t idx"
.Ft int
.Fn fido_credman_get_dev_metadata "fido_dev_t *dev" "fido_credman_metadata_t *metadata" "const char *pin"
.Ft int
.Fn fido_credman_get_dev_rk "fido_dev_t *dev" "const char *rp_id" "fido_credman_rk_t *rk" "const char *pin"
.Ft int
.Fn fido_credman_del_dev_rk "fido_dev_t *dev" const unsigned char *cred_id" "size_t cred_id_len" "const char *pin"
.Ft int
.Fn fido_credman_get_dev_rp "fido_dev_t *dev" "fido_credman_rp_t *rp" "const char *pin"
.Sh DESCRIPTION
The credential management API of
.Em libfido2
allows resident credentials on a FIDO2 authenticator to be listed,
inspected, and removed.
Please note that not all FIDO2 authenticators support credential
management.
To obtain information on what an authenticator supports, please
refer to
.Xr fido_cbor_info_new 3 .
.Pp
The
.Vt fido_credman_metadata_t
type abstracts credential management metadata.
.Pp
The
.Fn fido_credman_metadata_new
function returns a pointer to a newly allocated, empty
.Vt fido_credman_metadata_t
type.
If memory cannot be allocated, NULL is returned.
.Pp
The
.Fn fido_credman_metadata_free
function releases the memory backing
.Fa *metadata_p ,
where
.Fa *metadata_p
must have been previously allocated by
.Fn fido_credman_metadata_new .
On return,
.Fa *metadata_p
is set to NULL.
Either
.Fa metadata_p
or
.Fa *metadata_p
may be NULL, in which case
.Fn fido_credman_metadata_free
is a NOP.
.Pp
The
.Fn fido_credman_get_dev_metadata
function populates
.Fa metadata
with information retrieved from
.Fa dev .
A valid
.Fa pin
must be provided.
.Pp
The
.Fn fido_credman_rk_existing
function inspects
.Fa metadata
and returns the number of resident credentials on the
authenticator.
The
.Fn fido_credman_rk_remaining
function inspects
.Fa metadata
and returns the estimated number of resident credentials that can
be created on the authenticator.
.Pp
The
.Vt fido_credman_rk_t
type abstracts the set of resident credentials belonging to a
given relying party.
.Pp
The
.Fn fido_credman_rk_new
function returns a pointer to a newly allocated, empty
.Vt fido_credman_rk_t
type.
If memory cannot be allocated, NULL is returned.
.Pp
The
.Fn fido_credman_rk_free
function releases the memory backing
.Fa *rk_p ,
where
.Fa *rk_p
must have been previously allocated by
.Fn fido_credman_rk_new .
On return,
.Fa *rk_p
is set to NULL.
Either
.Fa rk_p
or
.Fa *rk_p
may be NULL, in which case
.Fn fido_credman_rk_free
is a NOP.
.Pp
The
.Fn fido_credman_get_dev_rk
function populates
.Fa rk
with the set of resident credentials belonging to
.Fa rp_id
in
.Fa dev .
A valid
.Fa pin
must be provided.
.Pp
The
.Fn fido_credman_rk_count
function returns the number of resident credentials in
.Fa rk .
The
.Fn fido_credman_rk
function returns a pointer to the credential at index
.Fa idx
in
.Fa rk .
Please note that the first credential in
.Fa rk
has an
.Fa idx
(index) value of 0.
.Pp
The
.Fn fido_credman_del_dev_rk
function deletes the resident credential identified by
.Fa cred_id
from
.Fa dev ,
where
.Fa cred_id
points to
.Fa cred_id_len
bytes.
A valid
.Fa pin
must be provided.
.Pp
The
.Vt fido_credman_rp_t
type abstracts information about a relying party.
.Pp
The
.Fn fido_credman_rp_new
function returns a pointer to a newly allocated, empty
.Vt fido_credman_rp_t
type.
If memory cannot be allocated, NULL is returned.
.Pp
The
.Fn fido_credman_rp_free
function releases the memory backing
.Fa *rp_p ,
where
.Fa *rp_p
must have been previously allocated by
.Fn fido_credman_rp_new .
On return,
.Fa *rp_p
is set to NULL.
Either
.Fa rp_p
or
.Fa *rp_p
may be NULL, in which case
.Fn fido_credman_rp_free
is a NOP.
.Pp
The
.Fn fido_credman_get_dev_rp
function populates
.Fa rp
with information about relying parties with resident credentials
in
.Fa dev .
A valid
.Fa pin
must be provided.
.Pp
The
.Fn fido_credman_rp_count
function returns the number of relying parties in
.Fa rp .
.Pp
The
.Fn fido_credman_rp_id
and
.Fn fido_credman_rp_name
functions return pointers to the id and name of relying party
.Fa idx
in
.Fa rp .
If not NULL, the values returned by these functions point to
NUL-terminated UTF-8 strings.
Please note that the first relying party in
.Fa rp
has an
.Fa idx
(index) value of 0.
.Pp
The
.Fn fido_credman_rp_id_hash_ptr
function returns a pointer to the hashed id of relying party
.Fa idx
in
.Fa rp .
The corresponding length can be obtained by
.Fn fido_credman_rp_id_hash_len .
Please note that the first relying party in
.Fa rp
has an
.Fa idx
(index) value of 0.
.Sh RETURN VALUES
The
.Fn fido_credman_get_dev_metadata ,
.Fn fido_credman_get_dev_rk ,
.Fn fido_credman_del_dev_rk ,
and
.Fn  fido_credman_get_dev_rp
functions return
.Dv FIDO_OK
on success.
On error, a different error code defined in
.In fido/err.h
is returned.
Functions returning pointers are not guaranteed to succeed, and
should have their return values checked for NULL.
.Sh SEE ALSO
.Xr fido_cbor_info_new 3 ,
.Xr fido_cred_new 3
.Sh CAVEATS
Credential management is a tentative feature of FIDO 2.1.
Applications willing to strictly abide by FIDO 2.0 should refrain
from using credential management.
Applications using credential management should ensure it is
supported by the authenticator prior to using the API.
Since FIDO 2.1 hasn't been finalised, there is a chance the
functionality and associated data structures may change.