External signatures are impossible to debug from a distance as it's
essentially your code that must be debugged. Look for hard-coded
assumptions, such as the key size, algorithms and so on.
Paulo
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of Rene
> Sent: Thursday, April 26, 2007 7:20 AM
> To: [email protected]
> Subject: Re: [iText-questions] Problem with signing PDFs when
> using2048-bitkey
>
> hi Paulo,
>
> thanks a lot for your answer.
>
> I increased the value form 128 to 256 for making room for the
> 2048-bit key.
> The signing process works fine.
>
> But when I open the PDF with the Acrobat Reader the build in
> verification
> says, that the document is not valid and has been modified.
> Any suggestions
> what do to now?
>
> Thanks...
>
> best regards,
> rene
>
> the signing process works fine and the
> "Paulo Soares" <[EMAIL PROTECTED]> schrieb im Newsbeitrag
> news:[EMAIL PROTECTED]
> > The examples assume 1024 long keys and that shows in things
> like "new
> > byte[128]". Make sure that you make room for longer keys.
> >
> > Paulo
> >
> > ----- Original Message -----
> > From: "Rene" <[EMAIL PROTECTED]>
> > To: <[email protected]>
> > Sent: Wednesday, April 25, 2007 1:53 PM
> > Subject: [iText-questions] Problem with signing PDFs when
> using 2048-bit
> > key
> >
> >
> >> Hi,
> >>
> >> I am using iText 1.4.8 and try to sign PDFs with external generated
> >> signatures.
> >>
> >> Up till know it works fine (using different SmartCards
> with 1024-bit key
> >> lenght). Today I tried a new card with 2048-bit RSA key and I get a
> >> problem when I try to copy the generated bytes into the
> PdfDictinary.
> >> The generated Data is to much (I think because of the
> 2048-bit key).
> >> I used the iText code example for inserting external signatures.
> >>
> >> Anyone a suggestion what to do to fix it? (with a SmartCard with a
> >> 1024-bit key everything works fine...).
> >>
> >> In the following you will find the code where occures the problem.
> >>
> >> Thanks for your help.
> >>
> >> Best regards,
> >> rene
> >>
> >> --------------------------------------
> >>
> >> PdfSigGenericPKCS sg = sap.getSigStandard();
> >> PdfLiteral slit = (PdfLiteral) sg.get(PdfName.CONTENTS);
> >> byte[] outc = new byte[(slit.getPosLength() - 2) / 2];
> >> PdfPKCS7 sig = sg.getSigner();
> >>
> >> /*
> >> create hash and signature...
> >> */
> >>
> >> // Sets the generated signature and hash of the PDF part(!!!)
> >> sig.setExternalDigest(job.getSignatur(), hash, "RSA");
> //$NON-NLS-1$
> >>
> >> // Creates the signedData-object and adds it into the temporary
> >> // PDF file.
> >> PdfDictionary dic = new PdfDictionary();
> >>
> >> byte[] ssig = sig.getEncodedPKCS7();
> >>
> >> System.arraycopy(ssig, 0, outc, 0, ssig.length); //sysout:
> >> PDF.Signatur.ssig: 3081 bytes, outc: 3014 bytes
> >> dic.put(PdfName.CONTENTS, new PdfString(outc)
> >> .setHexWriting(true));
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