PDF Lock / Unlock

In today's world, protecting sensitive documents is essential. Whether you are sending financial records, legal papers, or personal documents, ensuring that only the intended recipient can read your PDF is a baseline security need. The PDF Lock / Unlock tool by Tools Ayoob provides a fast, private, and easy method to encrypt and decrypt PDF files directly in your browser. Because encryption runs entirely on your device, there's no need to upload confidential files to a server — your data stays under your control.

This tool uses strong, modern cryptography (AES-GCM) to encrypt the raw bytes of a PDF file. When you choose a password to lock a PDF, the tool derives a cryptographic key from that password and encrypts the file. The result is a single downloadable file with a .enc extension. To unlock the file, the recipient simply provides the same password in the Unlock section; the browser decrypts the file and restores the original PDF for download. This approach has two major advantages: it is easy to use, and it avoids the privacy risk of sending your document to a third-party server.

Although standard PDF password protection embeds access control metadata in the PDF container itself, implementing the equivalent reliably requires specialized libraries often available only on the server. The method used here (client-side encryption-of-bytes) delivers practical security for most use cases: the encrypted file cannot be opened without the password, and modern browsers' Web Crypto API provides robust primitives for encryption and integrity checks. This is ideal for users who need a quick, trustworthy solution without creating accounts or installing software.

Important usage tips:

• Always pick a strong, unique password — at least 12 characters including numbers, letters and symbols.
• Keep a secure record of the password. If you lose it, decryption is computationally infeasible.
• Use secure channels (for example, direct messaging or phone) to share the password with the recipient — do not send the password and the encrypted file in the same email thread.

Common questions & troubleshooting:

Q: Is my PDF changed during encryption?
A: No, the original PDF bytes are taken and encrypted into a new package. The original PDF file remains unchanged on your device unless you overwrite it manually.

Q: Is this as secure as PDF-native password protection?
A: The cryptography used here (AES-GCM with derived keys) is strong and provides confidentiality and integrity. PDF-native protection is useful for workflows that require PDF viewers to enforce password entry inside the viewer UI; this tool instead wraps the PDF bytes with encryption. For most privacy-focused sharing scenarios, this method is appropriate and simpler.

Q: Can I open the locked file in other apps?
A: The encrypted file is a custom encrypted blob (.enc). To restore the original PDF, you'll need to decrypt using this tool or any compatible decryptor that follows the same format (AES-GCM with the same AD/nonce layout). After decryption, you will receive a standard PDF that can be opened by any PDF reader.

Q: Does the website keep my files?
A: No — all processing occurs in your browser. The site does not upload or store your files. That said, if you use the site on a device you do not trust, someone with access to that device could find files you downloaded. Always use trusted machines for sensitive work.

SEO & discoverability tips for site owners
If you are publishing this tool on your website, consider the following SEO best practices to help it rank and attract users:

• Include clear, descriptive titles and meta descriptions (examples are included in the template).
• Create a long-form help article (like the content on this page) that answers user questions and includes relevant keywords such as "encrypt PDF online", "password protect PDF", and "client-side PDF encryption".
• Offer structured data (JSON-LD) describing the tool as a SoftwareApplication or WebAPI to improve appearance in search results.
• Provide share buttons and social previews so users can easily promote the tool on social platforms.

This page and tool are provided by Tools Ayoob. If you find the tool helpful, please rate it, leave feedback in the comments section, and share it with colleagues and friends. Your feedback helps improve the tool and keeps it free for everyone.