public async void DecryptClicked (object sender, EventArgs e) {
			if (!ValidInputs()) {
				await DisplayAlert ("Missing input", "You must enter plaintext/ciphertext and the key", "OK");
				return;
			}
			var ps = new PontifexSolitaire (key.Text);
			ciphertext.Text = ps.Decrypt (plaintext.Text).Pad5() ;

			Tweet.Code = ciphertext.Text;
		}
		public async void DecryptClicked (object sender, EventArgs e) {
			if (!ValidInputs()) {
				await DisplayAlert ("Missing input", "You must enter plaintext/ciphertext and the key", "OK");
				return;
			}
			var ps = new PontifexSolitaire (key.Text);
			ciphertext.Text = ps.Decrypt (plaintext.Text).Pad5() ;

			// was for contest (now closed) http://blog.xamarin.com/xamarin-acquires-petzold/
			//Tweet.Code = ciphertext.Text;
		}
		static string TestKeyText (string key, string text)
		{
			var ps = new PontifexSolitaire (key);
			var output = ps.Decrypt (text).Pad5 ();
			return output;
		}