Youl’d have thought people would have “cottoned on” by Denton Scratch, Tatütata, … as a basis for defining legally binding documents, with all its complexities … doesn’t sound like such a wise idea, as eloquently demonstrated in the paper.Īs I’m fond of advising people when it comes to the likes of “Electronic Submission” DON’T. There are several more choices, including Xreader (Mint), evince (gnome) and mupdf, as well as Linux versions of Acrobat and FoxIt. The paper only mentions 3 Linux applications, of which only one is a stand-alone reader (okular), and the other two are editors.
#OKULAR DIGITAL SIGNATURE PDF#
In the mean time, I keep several PDF readers handy, in case one crashes while attempting to regurgitate a given document… To have PDF, which tries to be all things to all people, as a basis for defining legally binding documents, with all its complexities (interpreter implementation, content encryption, printing and text select permissions, font management, versioning, etc.) doesn’t sound like such a wise idea, as eloquently demonstrated in the paper. But then there is the proliferation of E-book standards, which fill a need quite close to PDF. Even some vendor specific alternatives like Microsoft’s XPS seem to have merits over PDF. If it weren’t of inertia and the sheer installed base, other formats could take over, such as SVG. Ewwwwwww… They might as well have kept PostScript after all. The distilled pages consisted only of the visible basic graphics operators (text, lines, surfaces, and geometric constructs, bitmaps) resulting from the program execution.īut the structure got clunkier with every new version and features, and an initial goal of human readability went overboard quite quickly. The format began nearly thirty years ago with good enough intentions, building on the success of Adobe’s PostScript printer control language, with which it shares many concepts, but without the programming primitives (loops, tests, variables, etc.). Surprised? PDF is IMO one hideous kludge. There’s a reason why a lot of my inbound spam contains a PDF attachment. That is getting your Arsinole over your Elbling. In some industries, it seems that PDF is the default format for publishing information if you’re not using PDF, you have to explain why. Most PDF documents do not have that requirement text/plain or HTML would serve as well or better. That is a special requirement it’s needed for advertising brochures, printing masters, and a few other arty targets. The single use-case for which I think PDF is an appropriate choice is a document containing content-elements such as formatted text and images, which must be presented as formatted in a particular way to carry the intended meaning. It includes a Turing-complete programming language, with which I am not familiar. The PDF format is extremely feature-rich (i.e.
Tags: academic papers, Adobe, hacking, signaturesĪdobe have a long history of designing and developing insecure products. In addition, we implemented PDF-Detector to prevent shadow documents from being signed or forensically detect exploits after being applied to signed PDFs.ĮDITED TO ADD (3/12): This was written about last summer. We introduce our tool PDF-Attacker which can automatically generate shadow attacks. Our results reveal that 16 (including Adobe Acrobat and Foxit Reader) of the 29 PDF viewers tested were vulnerable to shadow attacks. Since shadow attacks abuse only legitimate features,they are hard to mitigate. In contrast, shadow attacks use the enormous flexibility provided by the PDF specification so that shadow documents remain standard-compliant.
Compared to previous attacks, the shadow attacks do not abuse implementation issues in a PDF viewer. The shadow attacks circumvent all existing countermeasures and break the integrity protection of digitally signed PDFs. This paper introduces a novel class of attacks, which we call shadow attacks. As a consequence, affected vendors of PDF viewers implemented countermeasures preventing all attacks. revealed various parsing vulnerabilities in PDF viewer implementations.They showed attacks that could modify PDF documents without invalidating the signature. A user opening a signed PDF expects to see a warning in case of any modification. Interesting paper: “ Shadow Attacks: Hiding and Replacing Content in Signed PDFs“:Ībstract: Digitally signed PDFs are used in contracts and invoices to guarantee the authenticity and integrity of their content.
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