Provided by: libfido2-doc_1.3.1-1ubuntu2_all bug

NAME

     fido_cred_set_authdata, fido_cred_set_authdata_raw, fido_cred_set_x509, fido_cred_set_sig,
     fido_cred_set_clientdata_hash, fido_cred_set_rp, fido_cred_set_user,
     fido_cred_set_extensions, fido_cred_set_rk, fido_cred_set_uv, fido_cred_set_fmt,
     fido_cred_set_type — set parameters of a FIDO 2 credential

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_cred_set_authdata(fido_cred_t *cred, const unsigned char *ptr, size_t len);

     int
     fido_cred_set_authdata_raw(fido_cred_t *cred, const unsigned char *ptr, size_t len);

     int
     fido_cred_set_x509(fido_cred_t *cred, const unsigned char *ptr, size_t len);

     int
     fido_cred_set_sig(fido_cred_t *cred, const unsigned char *ptr, size_t len);

     int
     fido_cred_set_clientdata_hash(fido_cred_t *cred, const unsigned char *ptr, size_t len);

     int
     fido_cred_set_rp(fido_cred_t *cred, const char *id, const char *name);

     int
     fido_cred_set_user(fido_cred_t *cred, const unsigned char *user_id, size_t user_id_len,
         const char *name, const char *display_name, const char *icon);

     int
     fido_cred_set_extensions(fido_cred_t *cred, int flags);

     int
     fido_cred_set_rk(fido_cred_t *cred, fido_opt_t rk);

     int
     fido_cred_set_uv(fido_cred_t *cred, fido_opt_t uv);

     int
     fido_cred_set_fmt(fido_cred_t *cred, const char *ptr);

     int
     fido_cred_set_type(fido_cred_t *cred, int cose_alg);

DESCRIPTION

     The fido_cred_set_authdata set of functions define the various parameters of a FIDO 2
     credential, allowing a fido_cred_t type to be prepared for a subsequent call to
     fido_dev_make_cred(3) or fido_cred_verify(3).  For the complete specification of a FIDO 2
     credential and the format of its constituent parts, please refer to the Web Authentication
     (webauthn) standard.

     The fido_cred_set_authdata(), fido_cred_set_x509(), fido_cred_set_sig(), and
     fido_cred_set_clientdata_hash() functions set the authenticator data, attestation
     certificate, signature and client data hash parts of cred to ptr, where ptr points to len
     bytes.  A copy of ptr is made, and no references to the passed pointer are kept.  The
     authenticator data passed to fido_cred_set_authdata() must be a CBOR-encoded byte string, as
     obtained from fido_cred_authdata_ptr().  Alternatively, a raw binary blob may be passed to
     fido_cred_set_authdata_raw().

     The fido_cred_set_rp() function sets the relying party id and name parameters of cred, where
     id and name are NUL-terminated UTF-8 strings.  The contents of id and name are copied, and
     no references to the passed pointers are kept.

     The fido_cred_set_user() function sets the user attributes of cred, where user_id points to
     user_id_len bytes and name, display_name, and icon are NUL-terminated UTF-8 strings.  The
     contents of user_id, name, display_name, and icon are copied, and no references to the
     passed pointers are kept.  Previously set user attributes are flushed.  The user_id, name,
     display_name, and icon parameters may be NULL.

     The fido_cred_set_extensions() function sets the extensions of cred to the bitmask flags.
     At the moment, only the FIDO_EXT_HMAC_SECRET extension is supported.  If flags is zero, the
     extensions of cred are cleared.

     The fido_cred_set_rk() and fido_cred_set_uv() functions set the rk (resident key) and uv
     (user verification) attributes of cred.  Both are FIDO_OPT_OMIT by default, allowing the
     authenticator to use its default settings.

     The fido_cred_set_fmt() function sets the format of cred to fmt, where fmt must be either
     packed (the format used in FIDO 2) or fido-u2f (the format used by U2F).  A copy of fmt is
     made, and no references to the passed pointer are kept.  Note that not all authenticators
     support FIDO2 and therefore may not be able to generate packed.

     The fido_cred_set_type() function sets the type of cred to cose_alg, where cose_alg is
     COSE_ES256, COSE_RS256, or COSE_EDDSA.  The type of a credential may only be set once.  Note
     that not all authenticators support COSE_RS256 or COSE_EDDSA.

     Use of the fido_cred_set_authdata set of functions may happen in two distinct situations:
     when generating a new credential on a FIDO device, prior to fido_dev_make_cred(3) (i.e, in
     the context of a FIDO client), or when validating a generated credential using
     fido_cred_verify(3) (i.e, in the context of a FIDO server).

     For a complete description of the generation of a FIDO 2 credential and its verification,
     please refer to the FIDO 2 specification.  A concrete utilisation example of the
     fido_cred_set_authdata set of functions can be found in the cred.c example shipped with
     libfido2.

RETURN VALUES

     The error codes returned by the fido_cred_set_authdata set of functions are defined in
     <fido/err.h>.  On success, FIDO_OK is returned.

SEE ALSO

     fido_cred_exclude(3), fido_cred_verify(3), fido_dev_make_cred(3)