PDFsharp 6.2 Preview 1 was released

[ThomasHoevel]

More information here:
https://docs.pdfsharp.net/General/History.html#ps-6-2-0-pv1

[ZephyrZiggurat]

Regarding the upcoming digital signatures, is/will it possible to add a blank signature field? I have an existing pdf with basically just text on it (no form) and I'd like to be able to drop a blank digital signature field somewhere on one of the existing pages for a user to manually sign in Acrobat.

The best solution atm is to append a signature page from an imported pdf that was prepared in Acrobat. Is there any way else to achieve this?

Thanks for your work on this library!

[Havunen]

@ThomasHoevel

Is there some way to avoid calling AddSignatureComponentsAsync multiple times?

PDFsharp/src/foundation/src/PDFsharp/src/PdfSharp/Pdf/PdfDocument.cs

Lines 333 to 334 in 5fbf6ed

	if (_digitalSignatureHandler != null)
	await _digitalSignatureHandler.AddSignatureComponentsAsync().ConfigureAwait(false);

I implemented custom signer type to reserve enough space in the PDF for the signature and then later I will somehow fill this information in.

However it seems the Document will always add those signature components?

I'm planning the digital signature flow could go something like this:

1. Prepare the pdf document to be digitally signed, add the visual signatures and reserve space for signing.
2. Read the bytes out and send them to the client 1
3. client 1 will sign the document ( now the PDFSharp adds signing components again to the pdf document? )
4. later client 2 signs the document

In the signing phase, I would like to be able to edit the pdf only by writing the raw bytes to the digital signature block(s).
I thought implementing custom DigitalSignatureHandler but its not so easy because its static method is referenced from

PDFsharp/src/foundation/src/PDFsharp/src/PdfSharp/Pdf.Signatures/PdfSignatureHandler.cs

Lines 45 to 48 in 5fbf6ed

	public static DigitalSignatureHandler ForDocument(PdfDocument document, IDigitalSigner signer, DigitalSignatureOptions options)
	{
	return document._digitalSignatureHandler ??= new(document, signer, options);
	}

[ThomasHoevel]

Implement your own IDigitalSigner, add bytes for the signature in step 1 without actually signing it, add digital signature in step 3 without using PDFsharp (locate the placeholder for the signature in the PDF and fill it).

[Havunen]

ah, true. I didn't think of adding the bytes without PDFSharp. yeah that should work 👍

[Havunen]

I noticed the bytes of GetSignatureAsync(Stream stream) contains all the bytes for the document to be signed, so that means only one signature can be done at a time, otherwise it would invalidate the other signature as the the signatures cover each other.

Is there a method to create incremental version of the PDF so multiple signatures can be added one by one.

[Havunen]

#112

PR: #48

validator: https://ec.europa.eu/digital-building-blocks/DSS/webapp-demo/validation#SIGNATURE_Unit-Test_20241022-0703-CV

multiple signtures:
https://eideasy.com/pdf-pades-external-digital-signatures-using-etsi-cades-detached/

[diogopaulo]

When are you expecting to release PDFsharp 6.2? Thank you.

[mikethea1]

+1. We need the parsing fix. Looking forward to this release!

[ThomasHoevel]

We need the parsing fix.

Which fix?

[mikethea1]

@ThomasHoevel sorry for being vague. Based on the release notes, I assume the relevant one is "Bug in parsing object referenced".

Specifically, Sample file.pdf throws PdfReaderException when opened under 6.1.1 but works in 6.2-preview-1.