Converting excel to PDF

Here is the following code which used for converting excel to PDF.I need a solution for PDF to be converted as password protected below code is used for converting the excel to PDF without password.

Dim excelApplication As ApplicationClass = New ApplicationClass()
  Dim excelWorkbook As Workbook = Nothing
  Dim paramSourceBookPath As String = "C:\test\DDB_TEST.xlsx"
  Dim paramExportFilePath As String = "C:\test\Test.pdf"
  Dim paramExportFormat As XlFixedFormatType = _
      XlFixedFormatType.xlTypePDF
  Dim paramExportQuality As XlFixedFormatQuality = _
      XlFixedFormatQuality.xlQualityStandard
  Dim paramOpenAfterPublish As Boolean = False
  Dim paramIncludeDocProps As Boolean = True
  Dim paramIgnorePrintAreas As Boolean = True
  Dim paramFromPage As Object = Type.Missing
  Dim paramToPage As Object = Type.Missing
  Dim executableLocation As String = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)
  Dim xslLocation As String = Path.Combine(executableLocation, "DDL.pdf")
  Dim xslLocation1 As String = Path.Combine(executableLocation, "DDL1.pdf")
  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
      Try
          ' Open the source workbook.
          excelWorkbook = excelApplication.Workbooks.Open(paramSourceBookPath)
          ' Save it in the target format.
          If Not excelWorkbook Is Nothing Then
              excelWorkbook.ExportAsFixedFormat(paramExportFormat, _
                  xslLocation, paramExportQuality, _
                  paramIncludeDocProps, paramIgnorePrintAreas, _
                  paramFromPage, paramToPage, paramOpenAfterPublish)
              Dim picArray As Byte() = System.IO.File.ReadAllBytes(paramExportFilePath)
              '   System.IO.File.WriteAllBytes("hello.pdf", picArray)
          End If
      Catch ex As Exception
          ' Respond to the error.
      Finally
          ' Close the workbook object.
          If Not excelWorkbook Is Nothing Then
              excelWorkbook.Close(False)
              excelWorkbook = Nothing
          End If
          ' Quit Excel and release the ApplicationClass object.
          If Not excelApplication Is Nothing Then
              excelApplication.Quit()
              excelApplication = Nothing
          End If
          GC.Collect()
          GC.WaitForPendingFinalizers()
          GC.Collect()
          GC.WaitForPendingFinalizers()
         // EncryptPdf(xslLocation, xslLocation1, "text")
      End Try
  End Sub