@deftypefun {int} {gnutls_x509_privkey_export} (gnutls_x509_privkey_t @var{key}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size})
@var{key}: Holds the key

@var{format}: the format of output params. One of PEM or DER.

@var{output_data}: will contain a private key PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will export the private key to a PKCS@code{1}  structure for
RSA or RSA-PSS keys, and integer sequence for DSA keys. Other keys types
will be exported in PKCS@code{8}  form.

If the structure is PEM encoded, it will have a header
of "BEGIN RSA PRIVATE KEY".

It is recommended to use @code{gnutls_x509_privkey_export_pkcs8()}  instead
of this function, when a consistent output format is required.

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