Delphi mutual authentication

Question

I use the WinINet library to connect to a website.

Using the Internet Explorer (Win10) it works and shows me the message to select the certificate to use.

This is the delphi code I call:

FUNCTION TRAD.lastOrganization(): Integer;
VAR
  js:TlkJSONobject;
  ws: TlkJSONstring;
  url, resp: String;
  count,statusCodeLen, bodyCodeLen: Cardinal;
  header,tmp: String;
  buffer, body: String;
  statusCode: ARRAY [0 .. 1024] OF Char;
  bodyCode: ARRAY [0 .. 1024] OF Char;
  UrlHandle: HINTERNET;
BEGIN
  buffer := '00000000000000000000';
  url := contextUrl + '/rest/organization/count';
  UrlHandle := InternetOpenUrl(NetHandle, PChar(url), nil, 0, INTERNET_FLAG_RELOAD, 0);
  IF NOT ASSIGNED(UrlHandle) THEN
    SHOWMESSAGE('Unable to read the amount of Organization using the URL ' + url + ': ' +  SysErrorMessage(GetLastError));
  statusCodeLen := Length(statusCode);
  bodyCodeLen := Length(bodyCode);
  count := 0;
  IF HttpQueryInfo(UrlHandle, HTTP_QUERY_STATUS_CODE, @statusCode[0], statusCodeLen, count) THEN
  BEGIN
    buffer := statusCode;
    IF buffer <> '200' THEN
    BEGIN
      ShowMessage('While read amount of Organization I got a status code ' + buffer + ' but 200 was expected.');
      EXIT;
    END;
  END;

  count := 0;
  body := '';
  REPEAT
    FillChar(bodyCode, bodyCodeLen, 0);
    IF NOT InternetReadFile(UrlHandle, @bodyCode[0], bodyCodeLen, count) THEN
    BEGIN
      ShowMessage('Problem on reading from response stream while read the amount of Organization using the URL ' + url + '.');
      EXIT;
    END;
    IF count > 0 THEN
    BEGIN
      tmp := bodyCode;
      body := body + LeftStr(tmp, count);
    END;
  UNTIL count = 0;

  InternetCloseHandle(UrlHandle);
  Result := strtoint(body);
END;

If I call the method, I get this message:

Buuut, using the Edge-Browser I have to specify a certificate, and it works just great.

Question

How to specify the certificate?

Edit (new informations):

If I change the code to

FUNCTION TRAD.lastOrganization(): Integer;
VAR
  js:TlkJSONobject;
  ws: TlkJSONstring;
  url, resp: String;
  count,statusCodeLen, bodyCodeLen: Cardinal;
  header,tmp: String;
  buffer, body: String;
  statusCode: ARRAY [0 .. 1024] OF Char;
  bodyCode: ARRAY [0 .. 1024] OF Char;
  UrlHandle: HINTERNET;
BEGIN
  buffer := '00000000000000000000';
  url := contextUrl + '/rest/organization/count';
  UrlHandle := InternetOpenUrl(NetHandle, PChar(url), nil, 0, INTERNET_FLAG_RELOAD, 0);
  IF NOT ASSIGNED(UrlHandle) THEN
    raiseLastOSError();

It shows:

Answer 1

Consider the use of InternetErrorDlg

Code example:

function WebSiteConnect(const UserAgent: string; const Server: string; const Resource: string;): string;
var
  hInet: HINTERNET;
  hConn: HINTERNET;
  hReq:  HINTERNET;
  dwLastError:DWORD;

  nilptr:Pointer;
  dwRetVal:DWORD;

  bLoop: boolean;
  port:Integer;
begin
  hInet := InternetOpen(PChar(UserAgent), INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
  if hInet = nil then exit;
  hConn := InternetConnect(hInet, PChar(Server), INTERNET_DEFAULT_HTTPS_PORT, nil, nil, INTERNET_SERVICE_HTTP, 0, 0);
  if hConn = nil then
  begin
    InternetCloseHandle(hInet);
    exit;
  end;
  hReq := HttpOpenRequest(hConn, 'GET', PChar(Resource), 'HTTP/1.0', nil, nil, INTERNET_FLAG_SECURE, 0);
  if hReq = nil then
  Begin
    InternetCloseHandle(hConn);
    InternetCloseHandle(hInet);
    exit;
  end;

  bLoop := true;
  while bLoop do
  begin
    if HttpSendRequest(hReq, nil, 0, nil, 0) then
      dwLastError := ERROR_SUCCESS
    else
      dwLastError:= GetLastError();

    if dwLastError = ERROR_INTERNET_CLIENT_AUTH_CERT_NEEDED then
    begin
      dwRetVal:= InternetErrorDlg(application.handle, hReq, dwLastError,
      FLAGS_ERROR_UI_FILTER_FOR_ERRORS or
      FLAGS_ERROR_UI_FLAGS_GENERATE_DATA or
      FLAGS_ERROR_UI_FLAGS_CHANGE_OPTIONS,
      nilptr );

      if dwRetVal = ERROR_INTERNET_FORCE_RETRY then
        continue
      else  // CANCEL button
      begin
        InternetCloseHandle(hReq);
        InternetCloseHandle(hConn);
        InternetCloseHandle(hInet);
        exit;
      end;
    end
    else
      bLoop := false;
  end;
  Result:= ...
end;

Answer 2

Using WinHTTP (You can do the same with WinInetHTTP) you can set the certificate like this via ActiveX :

// Instantiate a WinHttpRequest object.
var HttpReq = new ActiveXObject("WinHttp.WinHttpRequest.5.1");

// Open an HTTP connection.
HttpReq.Open("GET", "https://www.fabrikam.com/", false);

// Select a client certificate.
HttpReq.SetClientCertificate(
            "LOCAL_MACHINE\\Personal\\My Middle-Tier Certificate");

// Send the HTTP Request.
HttpReq.Send();

So that easy with ActiveX but it's not really what you want (i gave you the example as illustration). So with the windows API, WinHTTP enables you to select and send a certificate from a local certificate store. The following code example shows how to open a certificate store and locate a certificate based on subject name after the ERROR_WINHTTP_CLIENT_AUTH_CERT_NEEDED error has been returned.

if( !WinHttpReceiveResponse( hRequest, NULL ) )
  {
    if( GetLastError( ) == ERROR_WINHTTP_CLIENT_AUTH_CERT_NEEDED )
    {
      //MY is the store the certificate is in.
      hMyStore = CertOpenSystemStore( 0, TEXT("MY") );
      if( hMyStore )
      {
        pCertContext = CertFindCertificateInStore( hMyStore,
             X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
             0,
             CERT_FIND_SUBJECT_STR,
             (LPVOID) szCertName, //Subject string in the certificate.
             NULL );
        if( pCertContext )
        {
          WinHttpSetOption( hRequest, 
                            WINHTTP_OPTION_CLIENT_CERT_CONTEXT,
                            (LPVOID) pCertContext, 
                            sizeof(CERT_CONTEXT) );
          CertFreeCertificateContext( pCertContext );
        }
        CertCloseStore( hMyStore, 0 );

        // NOTE: Application should now resend the request.
      }
    }
  }