[pdftex] Usage of \pdfcrypt

[Akira Kakuto]

From: Robert Howlett <rhowlett at mail.usyd.edu.au>
Subject: [pdftex] Usage of \pdfcrypt


> So, after reading the "readme" at ftp://bioinf.medicina.uniovi.es/pub/
> I tried putting
> \pdfcrypt{owner="me" none}
> at the start of one of my pdf files, to see what effect it had.

\pdfcrypt owner {me} none



                        pdfcrypt in pdfTeX-1.00a

To control this feature, I have added a new primitive named "\pdfcrypt".
If \pdfcrypt is found in the TeX source, the file is encrypted, otherwise
an unencrypted pdf file is generated as with the regular pdftex version.

\pdfcrypt must be placed early in the TeX source, before anything is
shipped out to the pdf output, otherwise it is simply ignored.

\pdfcrypt accepts the following optional parameters separated by spaces:

   \pdfcrypt parameter         meaning
   --------------------------  ----------------------------------------
   owner {the owner password}  to define the owner or security password

   user {the user password}    to define the user or open password

   print                       to give printing permission
   copy                        to allow selecting text and graphics
   edit                        to allow modifing (edit) the document
   annotate                    to allow changing notes and form fields
   all                         to allow all above

   noprint                     to deny printing permission
   nocopy                      to deny text and graphics selection
   noedit                      to deny document modification
   noannotate                  to deny changing notes and form fields
   none                        to deny all above
   --------------------------  ----------------------------------------


By default, no password is set, and permits are set to `all'.

Note that this syntax may still change as it is under discussion in the
pdftex list.


Usage examples:

\pdfcrypt none
 or
\pdfcrypt owner {anything} none
 will allow everybody to read the file but nobody will be able to print,
 copy, edit or annotate.


\pdfcrypt user {Knuth} none
 or
\pdfcrypt owner {Knuth} user {Knuth} none
 the password 'Knuth' (without the ') allows nothing else than reading
 the file. Nobody will be able to print, copy, edit or annotate.


\pdfcrypt owner {Donald} user {Knuth} none
 the password 'Donald' gives full access to the file;
 the password 'Knuth' allows nothing else than reading the file.


\pdfcrypt owner {Donald} user {Knuth} noprint
 the password 'Donald' gives full access to the file;
 the password 'Knuth' allows reading but not printing the file.


\pdfcrypt owner {Donald} user {Knuth} none print
 the password 'Donald' gives full access to the file;
 the password 'Knuth' allows reading and printing, but nothing else.


The following groups are equivalent:

this:
 \pdfcrypt owner {Donald} user {Knuth} none print

this:
 \pdfcrypt
  owner {Donald}
  user {Knuth}
  none
  print

this:
 \pdfcrypt owner {Donald}
 \pdfcrypt user {Knuth}
 \pdfcrypt none
 \pdfcrypt print

A note about Ghostscript:

* Starting from ghostscript 6.63 a fully functional pdf_sec.ps comes
  already with the standard package.

* Be aware that permits are totally ignored by ghostscript.

* The files where the user password is not set are fully open anyway.

* If the user password has been set, providing it gives full access
  to the file regarless of what permits have been set.

* The acrobat PDFref specs already warn that proper permit handling
  is fully dependent on the viewer implementation.

-- 
Akira Kakuto