Protect PDF with Password: AES-256 Military Encryption

Shield your confidential documents with a strong password before sharing. Instant local encryption, no server uploads.

AES-256 Encrypted

Instant

Dune Safe™

Mobile Ready

Setup

How to Password Protect a PDF?

Secure your file privacy in 3 steps.

Upload Document

Select the PDF file you wish to secure.

Create Password

Enter a strong password (we recommend 8+ characters).

Encrypt

The file is encrypted instantly and downloaded automatically.

Cutting-Edge Security & Encryption

Government-grade standards, now running in your browser.

AES-256 Bit

The strongest encryption standard publicly available.

Open Password

No one can view the content without the correct key.

Zero-Knowledge

We never see your password; it never leaves your computer.

Batch Processing

Apply the same password to multiple PDFs at once.

Compatible

Works with Adobe, Chrome, Mac, and Windows readers.

Free & Unlimited

Protect as many documents as you need at no cost.

Dune Safe™ Security Architecture

Why our tool is safer than desktop software.

Local Encryption (Client-Side)

Most sites ask you to upload files to their servers to password protect them. We don't. We use WebAssembly to execute the encryption algorithm on your device. It is mathematically impossible for us to intercept your document or key.

Your industrial secrets or tax data remain safe.

AES-256 Standard (Military Grade)

We use the _Advanced Encryption Standard_ with a 256-bit key length. To put it in perspective: even with all the world's supercomputers working together, this protection couldn't be brute-forced in millions of years.

Universal Legacy Compatibility

Although we use modern technology, the resulting file is compatible with any standard PDF reader (Adobe Acrobat, Foxit, Mac Preview, etc.). No special software is needed to open it, just the password.

AES-256 protection that opens in any reader.

Choosing a strong password

AES-256 is unbreakable, but a weak password isn't. Avoid: dictionary words, names, dates, sequential numbers (12345), keyboard patterns (qwerty). Use: 12+ characters mixing upper/lowercase, digits and symbols, ideally generated by a password manager. A passphrase like correct-horse-battery-staple is both strong and memorable. Send the PDF and the password through different channels (e.g. file via email, password via WhatsApp).

12+ chars + password manager = practically unbreakable.

Owner password vs user password

PDF supports two password levels: user password (required to open) and owner password (required to print/edit/copy). This tool sets the user password, anyone without it can't open the file at all. Owner-only passwords are weaker security: many readers ignore them, since the file content is unencrypted. If your goal is real privacy, always use a user password.

User password = the file is locked. Owner password = polite request many readers ignore.

When Should You Encrypt a PDF?

Personal Data (IDs & Payroll)

Sending IDs, payrolls, or medical data via email? It's irresponsible not to encrypt them. Protect your employees' or clients' identities.

Intellectual Property & Contracts

Prevent drafts or scripts from being read by prying eyes prematurely. Share the file via one channel and the password via another (e.g., WhatsApp).

Bank & Financial Statements

Protect your balance sheets and bank movements before sharing them with your accountant to avoid leaks in case of email hacks.

Security Datasheet

Specs of the encryption algorithm applied.

Protocol	Level
Algorithm	AES-256	N/A	Max Security
Key	256-bit Key	N/A	Brute Force Resistance
Privacy	Local-Only	100%	Strict Compliance

PDF Protection FAQs

Everything you need to know about keys and encryption.

If I forget the password, can you recover it?

No. Due to Zero-Knowledge security, we do not store your file or your password. If you lose the key, the content is irretrievable. We recommend using a password manager.

Is it safe to send sensitive data via email like this?

Yes, it is GDPR recommended. Sending unencrypted sensitive data is a risk. By adding a password, you guarantee only the recipient with the key can access it.

What encryption level is used?

We use AES-256 bit, the standard used by banks and military organizations. It is virtually immune to brute-force attacks with current technology.

Does the recipient need special software?

No. The protected PDF follows ISO standards. It opens with any free reader (Acrobat, Chrome, Preview) which will simply prompt for the password.

How do I add a password to a PDF for free?

Drop your PDF here, type a strong password (12+ chars recommended), click Encrypt. The encrypted file downloads automatically. Anyone trying to open it in Adobe Reader, Chrome, Mac Preview or any other PDF reader will be prompted for the password, without it, the content is unreadable.

Is my PDF uploaded to your server?

No. Encryption runs entirely in your browser via WebAssembly. The PDF, the password, and the encrypted output never leave your device. Verify it: open DevTools → Network tab during encryption, zero outgoing requests with file payload.

Can I encrypt scanned PDFs and forms?

Yes. Image-based scanned PDFs and interactive form PDFs both encrypt the same way, AES-256 protects the entire file structure. The form fields remain functional once unlocked, and OCR-extractable text stays extractable (after entering the password).

Can I encrypt multiple PDFs with the same password?

Yes, drop several PDFs at once and apply the same password to all. The tool processes them sequentially in your browser. Useful for batch-encrypting employee payslips, contract drafts, or financial reports before mass distribution.