@deftypefun {int} {gnutls_system_key_iter_get_info} (gnutls_system_key_iter_t * @var{iter}, unsigned @var{cert_type}, char ** @var{cert_url}, char ** @var{key_url}, char ** @var{label}, gnutls_datum_t * @var{der}, unsigned int @var{flags})
@var{iter}: an iterator of the system keys (must be set to @code{NULL}  initially)

@var{cert_type}: A value of gnutls_certificate_type_t which indicates the type of certificate to look for

@var{cert_url}: The certificate URL of the pair (may be @code{NULL} )

@var{key_url}: The key URL of the pair (may be @code{NULL} )

@var{label}: The friendly name (if any) of the pair (may be @code{NULL} )

@var{der}: if non-NULL the DER data of the certificate

@var{flags}: should be zero

This function will return on each call a certificate
and key pair URLs, as well as a label associated with them,
and the DER-encoded certificate. When the iteration is complete it will
return @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} .

Typically  @code{cert_type} should be @code{GNUTLS_CRT_X509} .

All values set are allocated and must be cleared using @code{gnutls_free()} ,

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.0
@end deftypefun