class RbNaCl::AEAD::XChaCha20Poly1305IETF

def do_decrypt(message, message_len, nonce, ciphertext, additional_data)
  self.class.aead_xchacha20poly1305_ietf_decrypt(message, message_len, nil,
                                                 ciphertext, data_len(ciphertext),
                                                 additional_data, data_len(additional_data),
                                                 nonce, @key)
end