iTextSharp: Disable PDF Printing

It took me ages to find out how to disable printing on a PDF file. You need to encrypt the file in order set copying and printing settings.  Here's how:

System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
writer.SetEncryption(null, encoding.GetBytes("12345678"), PdfWriter.ALLOW_COPY, PdfWriter.STRENGTH40BITS);

And this is how to enable printing if you still want the pdf to be encrypted.

System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
writer.SetEncryption(null, encoding.GetBytes("12345678"), PdfWriter.ALLOW_COPY | PdfWriter.ALLOW_PRINTING, PdfWriter.STRENGTH40BITS);