.\" Copyright (c) 2018-2021 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: August 29 2022 $
.Dt FIDO_CRED_VERIFY 3
.Os
.Sh NAME
.Nm fido_cred_verify ,
.Nm fido_cred_verify_self
.Nd verify the attestation signature of a FIDO2 credential
.Sh SYNOPSIS
.In fido.h
.Ft int
.Fn fido_cred_verify "const fido_cred_t *cred"
.Ft int
.Fn fido_cred_verify_self "const fido_cred_t *cred"
.Sh DESCRIPTION
The
.Fn fido_cred_verify
and
.Fn fido_cred_verify_self
functions verify whether the attestation signature contained in
.Fa cred
matches the attributes of the credential.
Before using
.Fn fido_cred_verify
or
.Fn fido_cred_verify_self
in a sensitive context, the reader is strongly encouraged to make
herself familiar with the FIDO2 credential attestation process
as defined in the Web Authentication (webauthn) standard.
.Pp
The
.Fn fido_cred_verify
function verifies whether the client data hash, relying party ID,
credential ID, type, protection policy, minimum PIN length, and
resident/discoverable key and user verification attributes of
.Fa cred
have been attested by the holder of the private counterpart of
the public key contained in the credential's x509 certificate.
.Pp
Please note that the x509 certificate itself is not verified.
.Pp
The attestation statement formats supported by
.Fn fido_cred_verify
are
.Em packed ,
.Em fido-u2f ,
and
.Em tpm .
The attestation type implemented by
.Fn fido_cred_verify
is
.Em Basic Attestation .
.Pp
The
.Fn fido_cred_verify_self
function verifies whether the client data hash, relying party ID,
credential ID, type, protection policy, minimum PIN length, and
resident/discoverable key and user verification attributes of
.Fa cred
have been attested by the holder of the credential's private key.
.Pp
The attestation statement formats supported by
.Fn fido_cred_verify_self
are
.Em packed
and
.Em fido-u2f .
The attestation type implemented by
.Fn fido_cred_verify_self
is
.Em Self Attestation .
.Pp
Other attestation formats and types are not supported.
.Sh RETURN VALUES
The error codes returned by
.Fn fido_cred_verify
and
.Fn fido_cred_verify_self
are defined in
.In fido/err.h .
If
.Fa cred
passes verification, then
.Dv FIDO_OK
is returned.
.Sh SEE ALSO
.Xr fido_cred_new 3 ,
.Xr fido_cred_set_authdata 3