http://xml.apache.org/fop/pdfencryption.html for how to set up the infrastructure and the relevant cocoon pages for passing options to the renderer.
Excellent, thanks for the pointer...
...I put it into the wiki and added a new way to configure the renderer...
http://wiki.cocoondev.org/Edit.jsp?page=FOPPDFEncryption
The new parameter passing works.
But the way through the user config file seems to fail. Maybe someone else has an idea why?
cheers -- Torsten