I was trying to print out some PDF files today that I had downloaded from a government website, and encountered the encrypted PDF phenomenon (I got a “This operation is not permitted” message or some such).

After much frustration, I found a site that said you can use the Ghostscript pdf2ps utility to convert the problematic PDF to a PostScript file, and then use ps2pdf to convert it back to a nice unencrypted PDF file for printing. Both pdf2ps and pdf2ps are available for GNU/Linux and Windows. GSView will also often open and print such PDFs just fine.