CODEWITHSUNDEEP
c#pdfitext
GermanSniper
GermanSniper

Reputation: 269

Itextsharp open password protected file modify it and adopt protection

I open an existing pdf. Checking for protection and ask for password if it is protected and open it with:

        PdfReader pdfReader = null;
        Stream outputStream = null;
        PdfStamper pdfStamper = null;

        try
        {
            pdfReader = GetPdfReaderObject();
            outputStream = new FileStream(filePathDestination, FileMode.Create, FileAccess.Write, FileShare.None);
            pdfStamper = new PdfStamper(pdfReader, outputStream);

                PdfLayer layer = new PdfLayer("watermark", pdfStamper.Writer);

                for (int pageIndex = 1; pageIndex <= pdfReader.NumberOfPages; pageIndex++) {
                    pdfStamper.FormFlattening = false;
                    iTextSharp.text.Rectangle pageRectangle = pdfReader.GetPageSizeWithRotation(pageIndex);
                    PdfContentByte pdfData = pdfStamper.GetOverContent(pageIndex);

                    pdfData.BeginLayer(layer);

                    PdfGState graphicsState = new PdfGState();
                    graphicsState.FillOpacity = 0.5F;
                    pdfData.SetGState(graphicsState);
                    pdfData.BeginText();

                    iTextSharp.text.Image watermarkImage = iTextSharp.text.Image.GetInstance(System.Drawing.Image.FromFile(watermarkImagePath), ImageFormat.Png);

                    float width = pageRectangle.Width;
                    float height = pageRectangle.Height;

                    watermarkImage.SetAbsolutePosition(width / 2 - watermarkImage.Width / 2, height / 2 - watermarkImage.Height / 2);

                    pdfData.AddImage(watermarkImage);
                    pdfData.EndText();
                    pdfData.EndLayer();
                }
            }
            pdfStamper.Close();
            outputStream.Close();
            outputStream.Dispose();
            pdfReader.Close();
            pdfReader.Dispose();

        } catch (Exception e) {
            ....
        }
    }

After my modifications I save it but the protection is destroyed.

Why the protection is destroyed? How can I save the protection from the origin document und add it to my modified one.

Regards

Upvotes: 2

Views: 8006

Answers (2)

mkl
mkl

Reputation: 95888

You use a PdfStamper to manipulate an existing PDF.

For any source PDF: If you want the result to be encrypted, you may use the SetEncryption method appropriately.

Have a look at the EncryptionPdf.cs, especially its method EncryptPdf:

PdfReader reader = ...;
using (MemoryStream ms = new MemoryStream())
{
    using (PdfStamper stamper = new PdfStamper(reader, ms))
    {
        stamper.SetEncryption(
                USER, OWNER, 
                PdfWriter.ALLOW_PRINTING, 
                PdfWriter.ENCRYPTION_AES_128 | PdfWriter.DO_NOT_ENCRYPT_METADATA
        );
    }
    return ms.ToArray();
}

Here USER and OWNER are the user and owner passwords of your choice. You might want to use a different set of permissions.

For already encrypted source PDFs you may alternatively choose to use the PdfStamper in append mode (i.e. use a PdfStamper constructor with a bool append parameter set to true). In that case the original encryption will also be applied to the updated PDF.

Upvotes: 3

Bruno Lowagie
Bruno Lowagie

Reputation: 77528

Which version of iText are you using?

When a password protected PDF was opened using the owner password and manipulated by PdfStamper, all original password protection was indeed removed. This changed in iText 5.3.5. See the changelog:

Important: we now keep the original owner password when stamping a document.

In other words: with all iText versions prior to 5.3.5, the owner password is lost. Starting with 5.3.5, it should be kept.

Upvotes: 1

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