[pdftex] Adding security pw to pdftex

[Karsten Tinnefeld]

> How difficult would be to add security password to pdf files
> generated by pdftex ? This feature would be very useful.

To create encrypted pdf, you need to license the rc4 algorithm from RSA 
Inc.  You can produce an identical file by using publically available 
software that implements the algorithm, but this is by definition not 
encrypted pdf, as RSA refuses to accept that the public algorithm does 
the same as rc4 and adobe has specified it using their property.

Check
	http://www.ozemail.com.au/~geoffk/pdfencrypt/
	http://www.ncat.edu/~grogans/algorithm_history_and_descriptio.htm
	http://partners.adobe.com/asn/developer/technotes/acrobatpdf.html
for more information.

> There is a package (htmldoc from Easy software), distributed
> in source under the GPL, that transforms html documents directly
> to pdf, and that has this ability implemented. This means that
> it shouldn't be too difficult to implement in pdftex as well
> without infringing copyrights (unless htmldoc is already doing so).

Why didn't you just point us to http://www.easysw.com/htmldoc/ ?

htmldoc-1.8.12/htmldoc/rc4.c has
 * "$Id: rc4.c,v 1.3 2000/06/05 17:55:45 mike Exp $"
 *
 *   RC4 functions for HTMLDOC.
 *
 *   Original code by Tim Martin
 *   Copyright 1999 by Carnegie Mellon University, All Rights Reserved

Karsten
-- 
Karsten Tinnefeld                       tinnefeld at ls2.cs.uni-dortmund.de
Fachbereich Informatik, Lehrstuhl 2                   T +49 231 755-4737
Universität Dortmund, D-44221 Dortmund, Deutschland   F +49 231 755-2047