OK, maybe I did stress the payload embedding part whereas the operation I don't know how to do is:
Given a PDF file, when I add a signature to that PDF file with iText and save it, is it possible to open the saved PDF file and revert all modifications done to the file when adding the signature? If it is possible, is it possible to do it programmatically with iText ? If yes, can somebody direct me to further reading or mention the right method(s) ? Thanks, Martin. On 28.08.2007, at 16:19, Paulo Soares wrote: > You can put whatever you want in the digital signature payload and > in the > signature dictionary. I don't see any issue here. If you add the > signature > in append mode you can even get the original PDF before signing. > > Paulo > > ----- Original Message ----- > From: "Martin Paljak" <[EMAIL PROTECTED]> > To: "Post all your questions about iText here" > <itext-questions@lists.sourceforge.net> > Sent: Tuesday, August 28, 2007 2:07 PM > Subject: Re: [iText-questions] Embedding external signatures inside > PDF > files > > >> >> On 28.08.2007, at 15:53, Paulo Soares wrote: >> >>> Each time a signature is applied new ids are created. Signing the >>> same PDF >>> twice will never have the same hash. >> That's not a requirement. The only requirement is to have a single >> PDF and a single signature that should be verifiable only with >> special software (that knows how to extract the needed information >> and knows what to do with the external signature format and how to >> verify it). >> >> The signature in embedded in the PDF file has nothing to do with PDF >> signatures - it should not be possible to verify it with adobe >> reader for example - only if a special plugin is installed. >> >> The idea is to have a proprietary signature format encapsulated into >> the PDF so that the end user would see a normal PDF with a 'unknown >> signature' but with special software it would be possible to turn the >> PDF inside out and and get the digital signature payload from inside >> the PDF. >> >> -- >> Martin Paljak >> http://martin.paljak.pri.ee > > > ---------------------------------------------------------------------- > --- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a > browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > _______________________________________________ > iText-questions mailing list > iText-questions@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/itext-questions > Buy the iText book: http://itext.ugent.be/itext-in-action/ -- Martin Paljak http://martin.paljak.pri.ee ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ iText-questions mailing list iText-questions@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/itext-questions Buy the iText book: http://itext.ugent.be/itext-in-action/
