How can I remove the printing protection from password-protected PDF files?
When PDF documents are visible but not printable there's an easy workaround when you are using GNU/Linux.
To do that, you have to use the two step procedure:
Revert back to normal pdf file
$ pdftops [your_protected_pdf_document.pdf] out.ps $ pstopdf [out.ps] broken_protection_pdf_document.pdf
And it's done. There is no more password protectin for your pdf document.