private async void Button_Tapped(object sender, TappedRoutedEventArgs e) { byte[] message = Encoding.UTF8.GetBytes(message_textbox.Text); if (publicKey != null) { byte[] dataToSend = PGP.Encrypt(message, publicKey, true, true); await MailHelper.ComposeEmailAsync(contact, "Encoded message", string.Empty, "message.pgp", dataToSend); } }