Can I open a password protected pdf (asking user for password) and then remove the password from the pdf?

[joeuy-dev]

As titled

[christianalberto]

Hi @joeuy-dev, yes, you can prompt the user for a password to open an encrypted PDF, and then export/save an unencrypted copy. However, how you achieve this depends on whether you are using PDF.js (a reader engine) or a full PDF manipulation library (like pdf-lib or pdfcpu).

1. Understanding PDF.js Limitations
   PDF.js is designed strictly as a rendering and viewing library, not a PDF editing or creation engine:

Opening: PDF.js natively handles password-protected files via the onPassword callback on getDocument().

Removing the password: PDF.js cannot directly re-serialize/save the PDF binary without encryption. If you need to output an unencrypted PDF file (e.g., for downloading), you must use a PDF manipulation library alongside PDF.js or directly in a backend node service / full-stack JS environment.

2. Client-Side Implementation (Browser)
   To open a password-protected PDF in the browser and save an unlocked version, pair PDF.js (or standard user input) with pdf-lib (or @pdf-lib/pdf-lib), which supports loading encrypted documents if given the password and re-saving them without protection.

Step 1: Open and Prompt for Password with PDF.js
When loading the document with pdfjsLib.getDocument(), supply the password directly or handle the onPassword callback:

import * as pdfjsLib from 'pdfjs-dist';

async function loadProtectedPDF(pdfArrayBuffer) {
  const loadingTask = pdfjsLib.getDocument({
    data: pdfArrayBuffer,
    // Provide password or handle onPassword event callback
    password: 'user_entered_password'
  });

  loadingTask.onPassword = (updatePassword, reason) => {
    // Prompt the user in UI, then call:
    const userEnteredPassword = prompt('Please enter the PDF password:');
    updatePassword(userEnteredPassword);
  };

  const pdfDoc = await loadingTask.promise;
  console.log('PDF unlocked and loaded successfully! Total pages:', pdfDoc.numPages);
}

Step 2: Remove Password and Save Unlocked Copy using pdf-lib
Once you have the valid password from the user, pass the raw PDF array buffer and the password to PDFDocument.load() in pdf-lib. When pdf-lib saves the document, it outputs an unencrypted PDF.

import { PDFDocument } from 'pdf-lib';

async function removePasswordAndDownload(pdfArrayBuffer, userPassword) {
  // Load the encrypted PDF using the validated password
  const pdfDoc = await PDFDocument.load(pdfArrayBuffer, { 
    password: userPassword 
  });

  // Exporting / saving automatically strips the password protection
  const unlockedPdfBytes = await pdfDoc.save();

  // Trigger browser download of the unlocked file
  const blob = new Blob([unlockedPdfBytes], { type: 'application/pdf' });
  const link = document.createElement('a');
  link.href = URL.createObjectURL(blob);
  link.download = 'unlocked_document.pdf';
  link.click();
}

3. Server-Side / CLI Alternative
   If you are performing this on a server (Node.js, Go, Python, etc.) or CLI:

Node.js: You can use pdf-lib or qpdf wrappers.

QPDF (CLI / Native Tool):

qpdf --password=USER_PASSWORD --decrypt input_protected.pdf output_unlocked.pdf
Python (pypdf / pikepdf):

import pikepdf

# Opens encrypted PDF with password and saves an unencrypted copy
with pikepdf.open('input.pdf', password='user_password') as pdf:
    pdf.save('unlocked.pdf')

Awesome! If this solution solves the issue for you, feel free to hit "Mark as answer" on the thread so others facing the same issue can find it easily! 🚀