The PDF reference/ISO 32000-1 DOES say that you can have as many pairs of values in the ByteRange as you wish...HOWEVER, Adobe Acrobat/Reader will consider ANYTHING more than 2 pairs (four numbers) as an INVALID range as it means there is potential for things to not be signed that should be.
This same recommendation is now codified in ETSI TS 102778, the PDF Advanced Electronic Signature (PAdES-1) standard as well. Leonard On 5/22/09 8:11 AM, "ABU" <[email protected]> wrote: After reading a lot a documents, from PDF-spec to technical recommendations, I feel that the signature validation subject is still unclear ... In particular I submit a PDF that is NOT validated by Acrobat Reader (de facto, the standard validator), but it is validated by other tools (e.g. iText). The Question: What is a ByteRange ? * The Official PDF-Spec says that ByteRange is an array of (pairs of) integer. * iText allows 2 or more pairs of integers. The following sample has 1 cert-signature plus 2 signatures http: //web.tiscali.it/irrational/exp-sign/X-Cert-AZ.pdf All the signatures are validated (integrity check) by iText method "verify" * A lot of Adobe docs say that ByteRange is made of 4 integers ONLY. * Acrobat Reader won't validate the above pdf ; If you try, you can see a generic message about "..damaged or suspect data in SigDict ..." (Note: since the certificate used (for all the 3 signatures) has been revoked, you should *temporarily* declared it as a trusted root certificate) If you inspect the above pdf, you can see that the 3rd signature has the following "uncommon" byterange ; /ByteRange [0 31771 56897 621 78000 4086] , that is the 3rd signature excludes the whole block of the 2nd signature, plus of course its own /Contents block. Do you think this kind of signature is a valid signature or not ? Do you think Acrobat signature validation is correct or should Acrobat be more permissive ? Aldo Promozione di Primavera ! Stampa le tue foto nei formati 13x17 e 13x19 a soli 0,11 eiuro. http://photo.tiscali.it ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com _______________________________________________ iText-questions mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/itext-questions Buy the iText book: http://www.1t3xt.com/docs/book.php Check the site with examples before you ask questions: http://www.1t3xt.info/examples/ You can also search the keywords list: http://1t3xt.info/tutorials/keywords/ -- Leonard Rosenthol PDF Standards Architect Adobe Systems Incorporated
------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com
_______________________________________________ iText-questions mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/itext-questions Buy the iText book: http://www.1t3xt.com/docs/book.php Check the site with examples before you ask questions: http://www.1t3xt.info/examples/ You can also search the keywords list: http://1t3xt.info/tutorials/keywords/
