How to Password Protect a PDF — And When You Should

Two Types of PDF Passwords

PDF security supports two distinct password types: Open password (User password) — required to open the document at all — and Permission password (Owner password) — required to change document permissions like printing or copying. Our Lock PDF tool applies an open password to prevent unauthorized access.

How to Password Protect a PDF for Free

Open the Lock PDF tool and upload your PDF.
Enter your chosen password. Use a strong password — at least 12 characters with a mix of letters, numbers, and symbols.
Click Lock and download the encrypted PDF.
Share the PDF and communicate the password through a separate, secure channel.

⚠️ Important: There is no "forgot password" option for PDF passwords. If you lose the password, the document is permanently inaccessible. Store passwords in a password manager.

What Encryption Is Used?

Modern PDF encryption uses AES (Advanced Encryption Standard) — the same algorithm used by governments and financial institutions for sensitive data. AES-256, the strongest variant, is computationally infeasible to brute-force with current technology.

When Should You Encrypt a PDF?

Legal documents containing personal or financial information
Medical records and health information
Business contracts and proposals sent by email
HR documents including salary information

Removing Password Protection

If you need to remove a password from a PDF you own (and know the password for), use our Unlock PDF tool. This is useful when you want to share a previously encrypted document more broadly.