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  parameters  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 statements 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 authenticator 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,  applications  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
       supported.  If flags is zero, the extensions of assert are cleared.

       The fido_assert_set_hmac_salt() and fido_assert_set_hmac_secret() functions 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 normally 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 default 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
       context  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)

Debian                                            May 23, 2018                       FIDO_ASSERT_SET_AUTHDATA(3)