class RbNaCl::AEAD::XChaCha20Poly1305IETF

def do_encrypt(ciphertext, ciphertext_len, nonce, message, additional_data)
  self.class.aead_xchacha20poly1305_ietf_encrypt(ciphertext, ciphertext_len,
                                                 message, data_len(message),
                                                 additional_data, data_len(additional_data),
                                                 nil, nonce, @key)
end