Reading a encrypted pdf with xpdf

[Gregory Nou]

Hi !
I have a pdf (a patent) which is protected against printing. I can read 
it with acrobat reader on windows at school, but I can't read it neither 
with xpdf nor gpdf, because both are asking me passwords. And 
ghostscript, which seemed to work under windows, does not work on my 
computer with freebsd.
Do someone know how I could read this document ?
I cannot really understand why they protect patents against printing by 
the way.

Cheers,

Grégory

NB : xpdf -v
xpdf version 3.00
Copyright 1996-2004 Glyph & Cog, LLC
I read there was a patch for version 0.96 but it seems a bit too old ;)