From: an anonymous contributor
To: dst@cs.cmu.edu
Subject: PDF discovery
Date: Fri, 30 Aug 2002

Thanks for the great webpage on PDF's.  I made a discovery that helped me 
out.  I thought I would tell you about it anonymously.

I found a way to get an Adobe eBook (that you can print) into unsecured PDF.

First, I printed to a PS printer with device set to FILE.  This gave me a 
.ps file.  Then I attempted to use ps2pdf in the Ghostscript package (7.04) 
to convert it, but it dumped at me "This PostScript file was created from an 
encrypted PDF file." whenever I tried to use it.  Perhaps another revision 
to pdf_sec.ps is in order.

I learned that the PS file was carring encrypted code ("% Removing the 
following eight lines is illegal, subject to the Digital Copyright Act of 
1998.") that checked for the PS file being executed in the context of a 
distiller and dumps the above error message if so.

Specifically, the code checks for the definition of currentdistillerparams 
and pdfmark and if it finds either, it barfs.  Now I don't know PS and I 
don't know Ghostscript, so you will no doubt cringe at this kludgy hack.  In 
gs_pdfwr.ps of the Ghostscript package find the section titled:

% Patch 'where' so that the distillerparams operators are only visible
% if the pdfwrite device is the current one, for the benefit of badly
% designed PostScript files that "know" they have to do something different
% if a distiller is processing them.

in this section change:

currentdevice .devicename /pdfwrite eq {

to

currentdevice .devicename /pdfwritexxx eq {

This change compels Ghostscript to not define currentdistillerparams for a 
pdf conversion which is enough to bypass the check in the PS file and allow 
a successful conversion to unprotected PDF using ps2pdf.

Cheers