Issue with Signature Widget Displaying Empty

[tusharp1206]

@Hopding
Hello ,

I'm encountering an issue with the display of the signature widget when using the node-signpdf library in conjunction with pdf-lib. Here's a brief overview of the problem I'm facing:

Problem:
When attempting to add a signature widget to a PDF document using the SignPDF class provided by node-signpdf, the signature widget is displayed as empty, without any visible content. Despite setting the correct rectangle coordinates, the widget does not show the expected content.

Steps to Reproduce:

Load a PDF document using pdf-lib.
Use the SignPDF class from node-signpdf to add a signature widget to the PDF document.
Specify the rectangle coordinates for the signature widget.
Save the modified PDF document.
Expected Behavior:
The signature widget should display the specified content within the defined rectangle coordinates.

Actual Behavior:
The signature widget appears empty, with no visible content displayed within the specified rectangle coordinates.

Additional Information:

I have verified that the rectangle coordinates are correctly set.
The PDF document format is compatible with the signature widget requirements.
Code Sample:
import {
PDFDocument,
PDFName,
PDFNumber,
PDFHexString,
PDFString,
} from "pdf-lib";
import SignPdf from "node-signpdf";
import fs from "fs";

import PDFArrayCustom from "./pdfArrayCustom.js";

export default class SignPDF {
constructor(pdfFile, certFile) {
this.pdfDoc = fs.readFileSync(pdfFile);
this.certificate = fs.readFileSync(certFile);
this.password = "my-pass";
}

/**

• @return Promise
  */
  async signPDF() {
  const signer = SignPdf.default;
  let newPDF = await this._addPlaceholder();
  // newPDF = signer.sign(newPDF, this.certificate,this.password);
  newPDF = signer.sign(newPDF, this.certificate, {
  passphrase: this.password,
  });
  return newPDF;
  }

/**

• @see How to create byte-range for digital signature #112 (comment)
• @returns {Promise}
  /
  async _addPlaceholder() {
  const loadedPdf = await PDFDocument.load(this.pdfDoc);
  const ByteRange = PDFArrayCustom.withContext(loadedPdf.context);
  const DEFAULT_BYTE_RANGE_PLACEHOLDER = '*********';
  const SIGNATURE_LENGTH = 3322;
  const pages = loadedPdf.getPages();

ByteRange.push(PDFNumber.of(0));
ByteRange.push(PDFName.of(DEFAULT_BYTE_RANGE_PLACEHOLDER));
ByteRange.push(PDFName.of(DEFAULT_BYTE_RANGE_PLACEHOLDER));
ByteRange.push(PDFName.of(DEFAULT_BYTE_RANGE_PLACEHOLDER));

const signatureDict = loadedPdf.context.obj({
  Type: 'Sig',
  Filter: 'Adobe.PPKLite',
  SubFilter: 'adbe.pkcs7.detached',
  ByteRange,
  Contents: PDFHexString.of('A'.repeat(SIGNATURE_LENGTH)),
  Reason: PDFString.of('We need your signature for reasons...'),
  M: PDFString.fromDate(new Date()),
});

const signatureDictRef = loadedPdf.context.register(signatureDict);

const widgetDict = loadedPdf.context.obj({
  Type: 'Annot',
  Subtype: 'Widget',
  FT: 'Sig',
  Rect: [520, 340, 620, 190], // Signature rect size
  V: signatureDictRef,
  T: PDFString.of('test signature'),
  F: 4,
  P: pages[0].ref,
});

const widgetDictRef = loadedPdf.context.register(widgetDict);

// Add signature widget to the first page
pages[0].node.set(PDFName.of('Annots'), loadedPdf.context.obj([widgetDictRef]));

loadedPdf.catalog.set(
  PDFName.of('AcroForm'),
  loadedPdf.context.obj({
    SigFlags: 3,
    Fields: [widgetDictRef],
  })
);

// Allows signatures on newer PDFs
// @see https://github.com/Hopding/pdf-lib/issues/541
const pdfBytes = await loadedPdf.save({ useObjectStreams: false });

return SignPDF.unit8ToBuffer(pdfBytes);

}

/**

• @param {Uint8Array} unit8
  */
  static unit8ToBuffer(unit8) {
  let buf = Buffer.alloc(unit8.byteLength);
  const view = new Uint8Array(unit8);

for (let i = 0; i < buf.length; ++i) {
  buf[i] = view[i];
}
return buf;

}
}

I would appreciate any insights or suggestions on how to resolve this issue. Thank you in advance for your assistance!

Thank You,