CODEWITHSUNDEEP
itext7
daustin
daustin

Reputation: 623

Getting pdf signatures with iText7

I have a scenario where I need to get signature information from a pdf with the iText7 library. The signature may or may not exist. When I instantiate a new SignatureUtil object for a PDF that does not have any digital signatures I get the exception

"There is no associate PdfWriter for making indirects."

. If an signature is there it works fine. I'm not sure how to correct this exception.

UPDATED to include code sample

Using reader As New PdfReader(pdfPath),
            pdf As New PdfDocument(reader)

                Dim util As New SignatureUtil(pdf)

                Dim signModel As String = "[Signature: {0} - {1}]"

                For Each signame As String In util.GetSignatureNames()
                    Dim whoisthis As PdfSignature = util.GetSignature(signame)
                    returnVal &= String.Format(
                        signModel,
                        whoisthis.GetName(),
                        whoisthis.GetReason
                        )
                Next

        End Using

Upvotes: 1

Views: 2611

Answers (1)

Alexey Subach
Alexey Subach

Reputation: 12312

The exception is thrown because there is no AcroForm in the document and SignatureUtil tries to add it, but there is no associated PdfWriter.

As a workaround you can check if a document contains an AcroForm:

PdfAcroForm.getAcroForm(document, false) != null

And only create SignatureUtil if there is an AcroForm. If there is no AcroForm there will be no signature fields.

Upvotes: 4

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