Junk Character in the encryption of file

Hi Experts,

My current requirement was to generate one file that will be used for encryption using client tool. But while encryption they are encountering one junk character in the start of the file due to which all process fails. I am confused why this junk character is coming as data in the file is perfect.

I am using following GUI_DOWNLOAD to download file-

This file gets downloaded to a certain path-

   call function 'GUI_DOWNLOAD'
    exporting
      filename                = lv_filename
      filetype                =   'ASC'
      codepage                = '4110'
    tables
      data_tab                = gi_output.

Downloaded file::

H;

P;00026973590;CN;SHA;4423170143;2011/09/05;上海嘉扬信息系统有限公司I;TESTING2640;2011/09/05;00026345590/0002061613/BV/0000124959;300.00

T;   1;300.00

Now after downloading

Following encryption method is used.

   call method cl_gui_frontend_services=>execute
    exporting
      application            = lv_app            "Application tool path
      parameter              = lv_param       "File Path

After Encryption :

Junk Character in the start of file

MIICswIBAD...

Now why this junk character comes if file data is correct. Please help.

Regards,

Ashish