FIDO_ASSERT_SET_AUTHD... BSD Library Functions Manual FIDO_ASSERT_SET_AUTHD...
NAME
fido_assert_set_authdata, fido_assert_set_authdata_raw,
fido_assert_set_clientdata, fido_assert_set_clientdata_hash,
fido_assert_set_count, fido_assert_set_extensions,
fido_assert_set_hmac_salt, fido_assert_set_hmac_secret,
fido_assert_set_up, fido_assert_set_uv, fido_assert_set_rp,
fido_assert_set_sig — set parameters of a FIDO2 assertion
SYNOPSIS
#include <fido.h>
typedef enum {
FIDO_OPT_OMIT = 0, /* use authenticator's default */
FIDO_OPT_FALSE, /* explicitly set option to false */
FIDO_OPT_TRUE, /* explicitly set option to true */
} fido_opt_t;
int
fido_assert_set_authdata(fido_assert_t *assert, size_t idx,
const unsigned char *ptr, size_t len);
int
fido_assert_set_authdata_raw(fido_assert_t *assert, size_t idx,
const unsigned char *ptr, size_t len);
int
fido_assert_set_clientdata(fido_assert_t *assert,
const unsigned char *ptr, size_t len);
int
fido_assert_set_clientdata_hash(fido_assert_t *assert,
const unsigned char *ptr, size_t len);
int
fido_assert_set_count(fido_assert_t *assert, size_t n);
int
fido_assert_set_extensions(fido_assert_t *assert, int flags);
int
fido_assert_set_hmac_salt(fido_assert_t *assert,
const unsigned char *ptr, size_t len);
int
fido_assert_set_hmac_secret(fido_assert_t *assert, size_t idx,
const unsigned char *ptr, size_t len);
int
fido_assert_set_up(fido_assert_t *assert, fido_opt_t up);
int
fido_assert_set_uv(fido_assert_t *assert, fido_opt_t uv);
int
fido_assert_set_rp(fido_assert_t *assert, const char *id);
int
fido_assert_set_sig(fido_assert_t *assert, size_t idx,
const unsigned char *ptr, size_t len);
DESCRIPTION
The fido_assert_set_authdata set of functions define the various parame-
ters of a FIDO2 assertion, allowing a fido_assert_t type to be prepared
for a subsequent call to fido_dev_get_assert(3) or fido_assert_verify(3).
For the complete specification of a FIDO2 assertion and the format of its
constituent parts, please refer to the Web Authentication (webauthn)
standard.
The fido_assert_set_count() function sets the number of assertion state-
ments in assert to n.
The fido_assert_set_authdata() and fido_assert_set_sig() functions set
the authenticator data and signature parts of the statement with index
idx of assert to ptr, where ptr points to len bytes. A copy of ptr is
made, and no references to the passed pointer are kept. Please note that
the first assertion statement of assert has an idx of 0. The authentica-
tor data passed to fido_assert_set_authdata() must be a CBOR-encoded byte
string, as obtained from fido_assert_authdata_ptr(). Alternatively, a
raw binary blob may be passed to fido_assert_set_authdata_raw().
The fido_assert_set_clientdata_hash() function sets the client data hash
of assert to ptr, where ptr points to len bytes. A copy of ptr is made,
and no references to the passed pointer are kept.
The fido_assert_set_clientdata() function allows an application to set
the client data hash of assert by specifying the assertion's unhashed
client data. This is required by Windows Hello, which calculates the
client data hash internally. For compatibility with Windows Hello, ap-
plications should use fido_assert_set_clientdata() instead of
fido_assert_set_clientdata_hash().
The fido_assert_set_rp() function sets the relying party id of assert,
where id is a NUL-terminated UTF-8 string. The content of id is copied,
and no references to the passed pointer are kept.
The fido_assert_set_extensions() function sets the extensions of assert
to the bitmask flags. At the moment, only the FIDO_EXT_CRED_BLOB,
FIDO_EXT_HMAC_SECRET, and FIDO_EXT_LARGEBLOB_KEY extensions are sup-
ported. If flags is zero, the extensions of assert are cleared.
The fido_assert_set_hmac_salt() and fido_assert_set_hmac_secret() func-
tions set the hmac-salt and hmac-secret parts of assert to ptr, where ptr
points to len bytes. A copy of ptr is made, and no references to the
passed pointer are kept. The HMAC Secret (hmac-secret) Extension is a
CTAP 2.0 extension. The fido_assert_set_hmac_secret() function is nor-
mally only useful when writing tests.
The fido_assert_set_up() and fido_assert_set_uv() functions set the up
(user presence) and uv (user verification) attributes of assert. Both
are FIDO_OPT_OMIT by default, allowing the authenticator to use its de-
fault settings.
Use of the fido_assert_set_authdata set of functions may happen in two
distinct situations: when asking a FIDO2 device to produce a series of
assertion statements, prior to fido_dev_get_assert(3) (i.e, in the con-
text of a FIDO2 client), or when verifying assertion statements using
fido_assert_verify(3) (i.e, in the context of a FIDO2 server).
For a complete description of the generation of a FIDO2 assertion and its
verification, please refer to the FIDO2 specification. An example of how
to use the fido_assert_set_authdata set of functions can be found in the
examples/assert.c file shipped with libfido2.
RETURN VALUES
The fido_assert_set_authdata functions return FIDO_OK on success. The
error codes returned by the fido_assert_set_authdata set of functions are
defined in <fido/err.h>.
SEE ALSO
fido_assert_allow_cred(3), fido_assert_verify(3), fido_dev_get_assert(3)
BSD May 23, 2018 BSD
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