Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

procedure TForm1.Button1Click(Sender: TObject);
 var
   s: String[255];
   c: array[0..255] of Byte absolute s;
   i: Integer;
 begin
   {encode}

   s := 'SwissDelphiCenter.ch';
   for i := 1 to Ord(s[0]) do c[i] := 23 xor c[i];
   Label1.Caption := s;

   {Decode}

   s := Label1.Caption;
   for i := 1 to Length(s) do s[i] := Char(23 xor Ord(c[i]));
   Label2.Caption := s;
 end;