faisal, faisal wrote > I am trying to add watermark image in a digitally signed PDF using > itextsharp but after adding image Adobe Acrobat says that my signature is > invalid although I am adding in append mode. I have also checked the > internal PDF structure after adding image and the signature content is > intact (have no temper). can someone please guide me what is wrong in my > code?
Already your implicit assumption taht you can apply a watermark to signed PDFs is wrong. A digital signature shall enable anyone to check whether the document was changed since signing or not. The signer can select a limited set of changes allowed to the document after his signature, but fundamentally changing the page content by adding an image never is allowed. You might want to check the PDF specification http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/PDF32000_2008.pdf section 12.8 on digital signatures and, furthermore, the Adobe Technical White Paper "Adobe Acrobat 9 Digital Signatures, Changes and Improvements" http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/reader/pdfs/readercomp_digitalsignatures.pdf section "Allowed and disallowed changes". Regards, Michael -- View this message in context: http://itext-general.2136553.n4.nabble.com/Digital-Signature-Corrupted-after-adding-watermark-image-tp4657457p4657459.html Sent from the iText - General mailing list archive at Nabble.com. ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d _______________________________________________ iText-questions mailing list iText-questions@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/itext-questions iText(R) is a registered trademark of 1T3XT BVBA. Many questions posted to this list can (and will) be answered with a reference to the iText book: http://www.itextpdf.com/book/ Please check the keywords list before you ask for examples: http://itextpdf.com/themes/keywords.php
