[pdftex] pdftex-pdfcrypt update

Ricardo Sanchez Carmenes carmenes at bioquimica.uniovi.es
Sat Mar 31 15:07:50 CEST 2001

On Fri, 30 Mar 2001, Greg Black wrote:

> "Mark A. Wicks" wrote:
> |     I hope that authors of PDF tools will respect the integrity of
> | encrypted PDFs.
> I hope they will treat the encryption with complete contempt.
> If somebody makes a document available to me in such a way that
> he wants me to be able to read it, then there is no reason for
> him to attempt to control the way I do that.

Unfortunatelly, this is an issue that will only rely on final
users. Programs already exist that ignore the permission flag,
and you don't need sophistated tools nor skills for that.

The permission flag only works with PDF reader programs that make
use of it, which is the case of the Acrobat Reader and xpdf.
Since these are the most widely used PDF readers, we can asum
that "most" (computer unskilled) final users will only make
use of the doc as their author wanted.

But there is no way to prevent more skilled computer users
to overcome the flags. You don't need knowledge of encryption
for that because the use of the flags is made by PDF readers
_after_ the PDF file has been decrypted with the provided PW.

The only reasonable way to avoid this people to modify/print etc
your doc, is not to provide him neither password.

And all that said, this is not really related to pdftex.

Regards, Ricardo.

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