Inno Setup - How to validate serial number online

Question

Using Inno Setup, setup.exe was given to a client, according to contract he is allowed only to use 2016 and 2017. But on 01-01-2018 he should not be able to con

Answer 1

Starting with a code from: Inno Setup - HTTP request - Get www/web content, you will get something like:

[Setup]
UserInfoPage=yes 

[Code]

{ Presence of the CheckSerial event function displays the serial number box. }
{ But here we accept any non-empty serial. }
{ We will validate it only in the NextButtonClick, }
{ as the online validation can take long. }
function CheckSerial(Serial: String): Boolean;
begin
  Result := (Serial <> '');
end;

function NextButtonClick(CurPageID: Integer): Boolean;
var
  WinHttpReq: Variant;
  Url: string;
begin
  Result := True;
  if CurPageID = wpUserInfo then
  begin
    WinHttpReq := CreateOleObject('WinHttp.WinHttpRequest.5.1');
    Url := 'https://www.example.com/serial.php?serial=' +
           WizardForm.UserInfoSerialEdit.Text;
    WinHttpReq.Open('GET', Url, False);
    WinHttpReq.Send('');
    { Depending on implementation of the server, use wither HTTP status code (.Status) }
    { or contents of returned "page" (.ResponseText) }
    { Here we use the HTTP status code: }
    { 200 = serial is valid, anything else = serial is invalid, }
    { and when invalid, we display .ResponseText }
    Result := (WinHttpReq.Status = 200);
    if not Result then
      MsgBox(WinHttpReq.ResponseText, mbError, MB_OK);
  end;
end;

A simple server-side validation PHP script (serial.php) would be like:

<?

if (empty($_REQUEST["serial"]) || ($_REQUEST["serial"] != "2017"))
{
    header("HTTP/1.0 401 The serial number is not valid");
    // error message to be displayed in installer
    echo "The serial number is not valid";
}

---

For consideration:

• This validation is not difficult to bypass, i.e. using a proxy server.
• It also does not prevent the user from extracting the files from the installer and installing them manually.
• You may consider instead an on-line download of the actual files only after validating the serial number.
• Or downloading some license file that the application will require for functioning. You need that anyway, if you want to enforce the application to stop working once the license expires.

---

For a similar question, see also
How to store serial numbers in a Sharepoint List, for to call from Inno Setup and verify if is autorized user?