Private browser encryption

Lock PDF Online with Password

Add a browser-based password lock to a PDF file. Your file is processed on your device and the locked file can be unlocked later on the Unlock PDF page with the same password.

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Select a PDF file to lock with a password. The original PDF is not uploaded to any server.

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Protect a PDF with a FreeChequePrint Encrypted Container

Sensitive PDFs are often shared through email or messaging apps. Before sharing, consider whether the recipient needs the complete document and whether a password-protected transfer method is appropriate.

A file can remain in downloads, chat history or cloud backups after it is sent. This tool places the original PDF bytes in a password-encrypted FreeChequePrint .lockedpdf container so that the matching Unlock PDF page and correct password are required to recover them.

The Critical Need for Local PDF Encryption in India

Bank statements, identity documents and tax records can contain information that should not be disclosed unnecessarily. Use redaction, access controls and an approved sharing method according to the sensitivity of the document.

This tool is for a PDF that is not already protected and needs to be placed in a FreeChequePrint encrypted container. It does not create a standard password-protected PDF that opens directly in Adobe Reader or a browser PDF viewer.

Why Not Just Use Other Online PDF Tools?

Different online tools use different processing models. Some upload documents to a remote server, while this tool is designed to encrypt the selected file in the current browser tab.

Read the privacy and security terms of any service before processing confidential documents. For files governed by an organisation’s policy, use approved software and storage rather than relying only on a public web tool.

How This Client-Side PDF Locker Works Under the Hood

The tool reads the selected PDF bytes in the browser, derives an encryption key from the password using PBKDF2 with SHA-256 and encrypts the bytes with AES-GCM. It then downloads a FreeChequePrint .lockedpdf container.

Processing time depends on file size, browser memory and device performance. The selected file is not intentionally sent to the site’s application server for encryption, but overall security also depends on the password, browser, device and sharing method.

Step-by-Step Guide to Locking Your PDF Correctly

Use the following steps to create and verify the encrypted container:

  1. Select Your Document: Choose the PDF file you want to protect. Make sure it's the final version, as editing an encrypted PDF later can be cumbersome.
  2. Choose a Strong Password: This is the most important step! Do not use your mobile number, your first name, or "123456". Those are easy to guess or test with automated password attempts. Use a combination of letters, numbers, and symbols.
  3. Communicate the Password Securely: If you are sending the locked PDF to your CA via email, DO NOT send the password in the same email. This defeats the purpose! Send the PDF via email and text them the password on WhatsApp or Signal. Split the communication channels.
  4. Lock and download: Click the lock button and save the generated .lockedpdf file. Large files may require more time and memory.
  5. Verify: Open the Unlock PDF page, select the new .lockedpdf file and confirm that the correct password recovers the original PDF. The container itself will not open in Chrome or Adobe Reader.

Password Best Practices for Indian Users

Avoid predictable document passwords based on a name, birth year, mobile number or other public information. A longer, unique passphrase is harder to guess.

Use a long, unique passphrase and communicate it through a separate channel from the container. Keep the original PDF in a secure location because a forgotten password cannot be recovered by this tool.

Frequently Asked Questions (FAQ)

1. Can someone bypass this password using a "PDF Unlocker" tool online?

The container uses authenticated encryption, but its practical security depends on the password, device and file handling. Keep the original safely stored and test recovery before sharing.

2. What happens if I forget the password I set?

If the password is forgotten, this tool cannot recover or reset it. Keep the original PDF securely stored or record the password in a reputable password manager.

3. I have a 50MB PDF containing scanned property documents. Will this tool work?

Large files require additional browser memory and may be slow or fail on older devices. Test the container and recovered PDF before deleting or moving the original.

4. Can I lock a PDF that is already locked by my bank?

No. This tool does not open or convert an existing standard password-protected PDF. It only encrypts an unprotected PDF into the FreeChequePrint .lockedpdf format.

5. Is it really true that no data is sent to your servers? Can I verify this?

The main encryption step is designed to run in the browser. Users can inspect the browser’s network panel, but should still consider extensions, device security, analytics and organisational policy when handling sensitive files.