@deftypefun {int} {gnutls_x509_ext_export_key_purposes} (gnutls_x509_key_purposes_t @var{p}, gnutls_datum_t * @var{ext})
@var{p}: The key purposes

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the key purposes type to a
DER-encoded PKIX ExtKeyUsageSyntax (2.5.29.37) extension. The output data in 
 @code{ext} will be allocated using @code{gnutls_malloc()} .

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

@strong{Since:} 3.3.0
@end deftypefun