private void ButtonDecrypt_Click(object sender, EventArgs e)
        {
            if (textBoxDecryptOriginal.TextLength == 0)
            {
                return;
            }
            var decrypt = chiper.Decrypt(textBoxDecryptOriginal.Text);

            textBoxDecrypt.Text = decrypt;
        }
        public string Download(string filename, string key, int alg, Download form)
        {
            try
            {
                StoredFile sf = svc.Download(Username, filename, Token);
                byte[]     f;
                switch (alg)
                {
                case 0: f = DoubleTransposition.Decrypt(sf.data, key, sf.hash); break;

                case 1: f = XTEA.Decrypt(sf.data, key, sf.hash); break;

                default: throw new Exception("You have not chosen an algorithm.");
                }
                form.Save(filename, f);
                return("File successfuly downloaded.");
            }
            catch (Exception e)
            {
                return(e.Message);
            }
        }