Simple XOR File Crypter

procedure TForm1.EnDecryptFile(pathin, pathout: string; Chave: Word);
var
  InMS, OutMS: TMemoryStream;
  cnt: Integer;
  C: byte;
begin
  InMS  := TMemoryStream.Create;
  OutMS := TMemoryStream.Create;
  try
    InMS.LoadFromFile(pathin);
    InMS.Position := 0;
    for cnt := 0 to InMS.Size - 1 DO
      begin
        InMS.Read(C, 1);
        C := (C xor not (ord(chave shr cnt)));
        OutMS.Write(C, 1);
      end;
    OutMS.SaveToFile(pathout);
  finally
    InMS.Free;
    OutMS.Free;
  end;
end;

Beispiel :

procedure TForm1.Button1Click(Sender: TObject);
begin
  OpenDialog1.Execute;
end;

procedure TForm1.BtnEnDeClick(Sender: TObject);
begin
  IF MessageDlg('ATTENTION'+#13+
                'Do not miss the password, or lose the file!',
                mtConfirmation, [mbYes, mbNo], 0) = mrYes THEN
    BEGIN
      EnDecryptFile(OpenDialog1.FileName,
                    OpenDialog1.FileName,
                    StrToInt(Edit1.Text));

      ShowMessage('Operation completed !');
    END;
end;