@deftypefun {int} {gnutls_cipher_add_auth} (gnutls_cipher_hd_t @var{handle}, const void * @var{ptext}, size_t @var{ptext_size})
@var{handle}: is a @code{gnutls_cipher_hd_t}  type

@var{ptext}: the data to be authenticated

@var{ptext_size}: the length of the data

This function operates on authenticated encryption with
associated data (AEAD) ciphers and authenticate the
input data. This function can only be called once
and before any encryption operations.

@strong{Returns:} Zero or a negative error code on error.

@strong{Since:} 3.0
@end deftypefun