Altering signed content *will* invalidate signatures. If one sig is based on another, altering that other signature is forbidden!
And I'm having a hard time coming up with a legitmate reason to do so... Care to explain your situation? --Mark Storer Senior Software Engineer Cardiff.com import legalese.Disclaimer; Disclaimer<Cardiff> DisCard = null; > -----Original Message----- > From: djdjdj [mailto:[email protected]] > Sent: Thursday, October 07, 2010 8:00 AM > To: [email protected] > Subject: [iText-questions] Clearing a Digital Signature Field's value. > > > Hello all, > > I've been researching this for the past few days and haven't > been able to expose what the issue is. I'm trying to clear > the values on a single digital signature field in a pdf using > itextsharp. I've stumbled upon this thread (which appears > wasn't completely answered and is now dead): > > http://osdir.com/ml/windows.dotnet.itextsharp.general/2008-07/ > msg00112.html > Clearing Digital Signature Field > > I've attempted to recreate the code that is in this thread > but just as the thread starter has said, it does not > accomplish what Paulo has suggested. > I'm already aware that the removal of a digital signature > field's values may invalidate the other digital signatures on > the pdf. However, this task should be a fairly easy thing to > accomplish given the depth of the itext/itextsharp library > but I haven't been able to figure out exactly how to do it. > > After walking through the code on that thread I've been able > to surmise that the widgets and merged values are probably > not neccessarily required to be cleared in order to wipe the > digital signature's actual values. > > I.E. : > > //Not needed? > PdfDictionary sig = (PdfDictionary)itm.widgets[0]; > sig.Remove(PdfName.V); sig.Remove(PdfName.AP); > > //Needed but does not change signature? > sig = (PdfDictionary)itm.values[0]; > sig.Remove(PdfName.V); > sig.Remove(PdfName.AP); > > //Not needed? > sig = (PdfDictionary)itm.merged[0]; > sig.Remove(PdfName.V); > sig.Remove(PdfName.AP); > > > Any ideas? > > Thanks! > -- > View this message in context: > http://itext-general.2136553.n4.nabble.com/Clearing-a-Digital- > Signature-Field-s-value-tp2966934p2966934.html > Sent from the iText - General mailing list archive at Nabble.com. > > -------------------------------------------------------------- > ---------------- > Beautiful is writing same markup. Internet Explorer 9 > supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, > and DOM L2 & L3. > Spend less time writing and rewriting code and more time > creating great experiences on the web. Be a part of the beta today. > http://p.sf.net/sfu/beautyoftheweb > _______________________________________________ > iText-questions mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/itext-questions > > 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 > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.862 / Virus Database: 271.1.1/3170 - Release > Date: 10/05/10 23:34:00 > ------------------------------------------------------------------------------ Beautiful is writing same markup. Internet Explorer 9 supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. Spend less time writing and rewriting code and more time creating great experiences on the web. Be a part of the beta today. http://p.sf.net/sfu/beautyoftheweb _______________________________________________ iText-questions mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/itext-questions 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
