Alexander, Alexander Raitskin wrote > Is there a way to sign several a PDFs and finally to sign *and* encrypt > it?
Whenever you have a PDF with signatures, these signatures contain hash values of some revision of the PDF (with the signature bytes themselves excluded). When you want encrypt such a PDF, your intention surely encompasses the encryption of all the text already signed; thus, when you encrypt the file, you change all the string values in the document. This implies that the hash values calculated during signature creation don't match the hash values after encryption anymore. (Actually there are other problems, too, obstructing the encryption of PDFs with integrated signatures.) Thus, in a nutshell, encrypting a document breaks any formerly applied signatures in it. Regards, Michael PS: The situation may differ in case of XFA XML signatures: If those XML signatures are checked only after decryption of the XFA XML stream, they might not be invalidated by encrypting the document. -- View this message in context: http://itext-general.2136553.n4.nabble.com/sign-and-encrypt-a-signed-file-tp4655614p4655619.html Sent from the iText - General mailing list archive at Nabble.com. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ 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
