Hello, My name is Gökçen Eraslan, I'm a FLOSS developer and Computer Science M.S. student in Bogazici University of Turkey. Previously I worked for TUBITAK (The Scientific and Technological Research Council of Turkey, equivalent of NSF in Turkey) for 4 years. I was the developer and release manager of the Pardus Linux distribution project[1] which is a government funded project aiming to develop a mature Linux distribution along with technological innovations (a brand new package manager, installer, configuration system etc.) as well as encouraging free software development in Turkey in order to avoid the massive sums needed for the license fees of proprietary operating systems. But lately Pardus project is somehow suspended (details here[2]) and most of the core developers left Pardus.
Anyway, my GSoC proposal is to add digital signing to PDF export feature. This is an idea from the ideas page[3]. Although I've fixed an easyhack[4], I'm not experienced in LibreOffice codebase but since document signing (not PDF signing) is supported by LibreOffice right now, (I hope) listing and choosing certificates (provided from the certificate database of Mozilla applications) will be easy using the existing classes. Right now, I'm reading PDF reference documents[5] published by Adobe. Next planned step is to be familiar with PKCS#1, PKCS#7 and PKCS#12 standards and to learn code pointers to PDF export code. I also have some question about the implementation details: * The signing method: What kind of signature handler we may use? ByteRange method is sufficient and for the SubFilter value of the signature dictionary, adbe.x509.rsa.sha is OK, right? In this case, Cert entry of the Signature dictionary will contain X.509 certificate chain and Contents key wil contain the byte range digest. * Is the MDP (modification detection and prevention) required? This is used for object signatures, right? But the byte-range based document signatures is more suitable. I think I must also investigate the status of the digital signature verification in Linux PDF readers and maybe poppler, so the users must be able to verify the signed PDF files :) * Which PDF version should be preferred? As far as I can see, SHA256 digestion is introduced in PDF 1.6, so the decision of digest method may effect the minimum PDF version to be used, right? That's all for now. Cheers. [1] http://www.pardus.org.tr/en [2] http://developer.pardus.org.tr/people/ozan/blog/?p=144 [3] http://wiki.documentfoundation.org/Development/Gsoc/Ideas#Sign_PDF_documents_on_export [4] https://bugs.freedesktop.org/show_bug.cgi?id=46538 [5] http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_archives/PDFReference15_v5.pdf -- Gökçen Eraslan _______________________________________________ LibreOffice mailing list LibreOffice@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libreoffice