The signature is there to show that the document was not changed. If you
change the document the signature becomes invalid. It's not rocket science.
Paulo
----- Original Message -----
From: "mohan alagurajan" <[EMAIL PROTECTED]>
To: <itext-questions@lists.sourceforge.net>
Sent: Friday, July 07, 2006 10:39 AM
Subject: [iText-questions] Watermark and Signatures
>
> Hi All,
>
> I am new to iText. I have a requirement where I have to apply watermark to
> an existing PDF, the PDF has digital signatures.
>
> I am using PdfStamper to apply the watermark, the code snippet is as
> follows:
>
> PdfReader reader = new PdfReader("C:/form.pdf");
> int n = reader.getNumberOfPages();
> FileOutputStream stampOutput = new FileOutputStream("C:/stamp.pdf");
> PdfStamper stamper = new PdfStamper(reader, stampOutput);
> PdfContentByte under;
> PdfContentByte over;
> BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA, BaseFont.WINANSI,
> BaseFont.EMBEDDED);
>
> int i = 0;
> while (i < n) {
> over = stamper.getOverContent(i);
> over.beginText();
> over.setFontAndSize(bf, 8);
> over.setTextMatrix(30, 30);
> over.showText("Watermark Text");
> over.setFontAndSize(bf, 8);
> over.endText();
> }
> stamper.close();
>
> The watermark works fine, but I face issue with the signatures, the
> digital
> signature becomes invalid. When I try to view the signature in the output
> PDF I get the following error:
>
> Error during signature verification.
>
> Unexpected byte range values defining scope of signed data.
> Details: byte range of signature is invalid
>
> I also noticed that the ouput file(87 KB) is smaller in size than the
> input
> file(103 KB).
>
> Can anyone point out why the signature becomes invalid, what is wrong with
> the code and what is the right approach?
>
> And also why the size of the output file decreases?
>
> You help is very much appreciated!
>
> Thanks in advance!
>
> Regards,
> Mohan Alagurajan
> --
> View this message in context:
> http://www.nabble.com/Watermark-and-Signatures-tf1905401.html#a5214379
> Sent from the iText - General forum at Nabble.com.
>
>
> Using Tomcat but need to do more? Need to support web services, security?
> Get stuff done quickly with pre-integrated technology to make your job
> easier
> Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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