Password Protection for PDF

Dear Gurus ,

I have come across the situation in which I want to converted PDF to be password protected .

I have converted the smartform into PDF using OTF and sending as a mail .

But now I want to add the Functionality of adding the Password how to Proceed for this .

for converting PDF I am using the Funtion Modukle :

CALL FUNCTION 'CONVERT_OTF'
   EXPORTING
     format                      = 'PDF'
     max_linewidth               = 132
*     ARCHIVE_INDEX               = ' '
*     COPYNUMBER                  = 0
*     ASCII_BIDI_VIS2LOG          = ' '
*     PDF_DELETE_OTFTAB           = ' '
   IMPORTING
     BIN_FILESIZE                = v_len_in
*     BIN_FILE                    =
    TABLES
      otf                         = it_otf
      lines                       = it_lines.

How to Make this Converted PDF password protected ?

I cant use ADOBE life cycle Designer for this . Please help 😔

Thanks & Regards ,

Aryan