Criptografia de campo

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

Const
  InputBoxMessage = WM_USER + 200;  //Codigo

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);

  private
    procedure InputBoxSetPasswordChar(var Msg: TMessage); message InputBoxMessage; //Codigo
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.InputBoxSetPasswordChar(var Msg: TMessage);
var
  hInputForm, hEdit: HWND;
begin
  hInputForm := Screen.Forms[0].Handle;
  if (hInputForm <> 0) then
  begin
    hEdit := FindWindowEx(hInputForm, 0, 'TEdit', nil);
    SendMessage(hEdit, EM_SETPASSWORDCHAR, Ord('*'), 0);
  end;
end;


procedure TForm1.Button1Click(Sender: TObject);
var
  InputString: string;
begin
  PostMessage(Handle, InputBoxMessage, 0, 0);
  InputString := InputBox('Senha', 'Digite a senha', '');
end;

end.