Bug 70704

Summary:	Password required on document that opens without using Acrobat
Product:	poppler	Reporter:	Robinson Tryon (qubit) <qubit>
Component:	general	Assignee:	poppler-bugs <poppler-bugs>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	high	CC:	arnaud.versini, m.weghorn, qubit
Version:	unspecified
Hardware:	x86 (IA32)
OS:	Linux (All)
See Also:	https://bugs.documentfoundation.org/show_bug.cgi?id=70705
Whiteboard:
i915 platform:		i915 features:
Bug Depends on:
Bug Blocks:	70705
Attachments:	Slides from LibreOffice2013 presentation Slides from LibreOffice2013 presentation - cleaned with MuPDF

Description Robinson Tryon (qubit) 2013-10-20 21:16:21 UTC

Created attachment 87897 [details]
Slides from LibreOffice2013 presentation

Hi,

LibreOffice is in the process of assembling slides from our last conference and one of our presenters gave us a PDF export [see attachment] of PowerPoint slides which opens in Adobe Acrobat on Windows without a password, but gives a "Password required" prompt on Evince 3.4.0 on Ubuntu 12.04.3.

Testing with pdf2ps 9.05, gives the following error:
"   **** This file uses an unknown standard security handler revision: 6"

...which looks like this bug:
http://bugs.ghostscript.com/show_bug.cgi?id=693305

(I stole the title from bug 3498, but I believe this is a separate issue :-)

Comment 1 Albert Astals Cid 2013-10-20 22:04:43 UTC

FWIW Adobe Acrobat on Linux doesn't open the file here either.

Comment 2 James Cloos 2013-10-21 05:06:36 UTC

Interesting.

GhostScript also is unable to open it, but mupdf can do so.

The mupdf src has this comment about /R 6:

/*
 * Compute an encryption key (PDF 1.7 ExtensionLevel 8 algorithm)
 *
 * Adobe has not yet released the details, so the algorithm reference is:
 * http://esec-lab.sogeti.com/post/The-undocumented-password-validation-algorithm-of-Adobe-Reader-X
 */

That will be needed to handle this document.

-JimC

Comment 3 Robinson Tryon (qubit) 2013-10-23 14:35:27 UTC

Created attachment 88038 [details]
Slides from LibreOffice2013 presentation - cleaned with MuPDF

(In reply to comment #2)
> Interesting.
> 
> GhostScript also is unable to open it, but mupdf can do so.

Excellent. Looks like we can mupdf to convert the PDF files.

WORKAROUND:

Build MuPDF from source (3379bea "Remove duplicated line.") and use mutool to massage a (seemingly) encrypted PDF into something more standard.

For example:
qubit@loopbackoffice:~/src/mupdf/build/debug/mutool clean LibO\ Conf\ 2013\ as\ presented.pdf LibO-Conf-2013_cleaned-with-mupdf.pdf

Evince can open the output PDF properly.

Comment 4 Michael Weghorn 2018-01-11 08:10:42 UTC

This is no longer reproducible since support has been added to poppler a while ago. This is also documented in the referenced LibreOffice bug report.

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