@deftypefun {int} {gnutls_x509_crt_set_key_usage} (gnutls_x509_crt_t @var{crt}, unsigned int @var{usage})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{usage}: an ORed sequence of the GNUTLS_KEY_* elements.

This function will set the keyUsage certificate extension.

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