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From: Gunnar Wolf on 20 Apr 2010 10:00
Merciadri Luca dijo [Tue, Apr 20, 2010 at 02:00:13PM +0200]:
> > As you quote, others have told you the PDF-provided security is
> > fake. It is just a flag flipped to tell the reader program to pretty
> > please make life miserable for the user.
> >
> Yes, but it is often sufficient to prevent _beginners_ from hacking the
> whole stuff.

Yet, you say in your previous reply they would be able to remove the
watermark from the document. That is clearly more complicated.

> > Whatever can be displayed on screen can be captured (i.e. with the
> > common "PrtScr" keybinding in many environments). If you want to
> > distribute material and make it hellish to your users to print it,
> > copy from it or use it in any useful way, why don't you send the
> > document as a .jpg file?
> >
> With such files (.jpg ones) they can print it directly, can't they?

If you distribute an image file in such a fashion it can be read on
screen but lacks enough resolution to be good for printing, fewer
people will print it. Of course, depends on what you want to achieve,
on the nature of the document.

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Gunnar Wolf • gwolf(a)gwolf.org • (+52-55)5623-0154 / 1451-2244


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From: Gunnar Wolf on 19 Apr 2010 19:00
Merciadri Luca dijo [Mon, Apr 19, 2010 at 05:32:51PM +0200]:
> > Pdf "anti-features" are fake security. Don't trust on them, never.
> And what do you suggest if one wants some real protection _and_ the
> benefits of a format like PDF? Thanks.

Thing is, PDF is a printing-oriented format. It is a close descendent
of PostScript, a full-fledged programming language, but geared towards
printers. The main point that makes PDF a more convenient format is
that Acrobat made a big campaign to distribute its PDF reader program.

As you quote, others have told you the PDF-provided security is
fake. It is just a flag flipped to tell the reader program to pretty
please make life miserable for the user.

What do you want to achieve with this _real_ protection you say?
Whatever can be displayed on screen can be captured (i.e. with the
common "PrtScr" keybinding in many environments). If you want to
distribute material and make it hellish to your users to print it,
copy from it or use it in any useful way, why don't you send the
document as a .jpg file?

Greetings,

--
Gunnar Wolf • gwolf(a)gwolf.org • (+52-55)5623-0154 / 1451-2244


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