PDF power tools
Password protect a PDF
Apply AES-256 passwords and viewer permission controls locally. Your document is processed locally and is never uploaded to Novus PDF Studio.
Apply AES-256 passwords and viewer permission controls locally.Encrypts the PDF with AES-256. The open password is required to view the file; the owner password grants full access and controls the viewer permissions you select below.
Drop PDF here
Files stay in this browser session. Maximum 200 MB each.
Your document preview will appear here.
Choose a PDF to begin.
About this tool
Emailing a document with personal, financial, or medical details? Encrypting it first means only someone with the password can open it. This tool applies genuine AES-256 encryption — the same standard used by desktop PDF suites — entirely inside your browser. The document and both passwords stay on your device; there is no server that could log them.
You set two passwords: the open password recipients type to view the file, and an owner password that retains full control and can later remove the protection. You also choose viewer permissions — whether readers may print, copy text, modify content, or fill forms. After encryption the tool re-opens its own output to verify the protection took effect before the download starts.
How to protect step by step
- 1
Upload the PDF
Drop the file or click Choose PDF. A preview and page count confirm you have the right document.
- 2
Set both passwords
Enter an open password (for recipients) and a different owner password (for you), each at least eight characters, and confirm both.
- 3
Choose viewer permissions
Toggle printing, copying, modification, and form-filling/annotation. Unchecked actions are flagged as disallowed for anyone opening with the open password.
- 4
Protect and download
Click Protect PDF. The file is encrypted locally with AES-256, verified, and downloaded.
- 5
Share the password safely
Send the open password through a different channel than the file itself — e.g. file by email, password by text message.
When to use it
- Sending tax, payroll, or benefits documents by email
- Sharing medical records or insurance claims
- Distributing contracts where copying or modification should be restricted
- Storing sensitive archives that should not open without a password
Tips
- Use a passphrase (four random words) rather than a short complex string — longer beats fancier.
- The permission chips under the preview summarize your current settings at a glance.
- Verify the output by opening it: you should be prompted for the password immediately.
Good to know
- Passwords must be at least eight characters, and open/owner must differ.
- Permission flags depend on viewer enforcement; only the open password is cryptographic protection.
Protect questions, answered
How strong is the encryption?
AES-256 — the current PDF standard (PDF 2.0 / ISO 32000-2) and the same algorithm used by desktop tools like Acrobat. With a strong password, the content is computationally infeasible to recover without it.
What's the difference between the open and owner passwords?
The open (user) password is required to view the document at all. The owner password grants full access regardless of the permission flags and is what you'd use later to remove protection with the Unlock tool. They must be different — treat the owner password as yours alone.
Are the permission restrictions absolute?
Permission flags (no printing, no copying, etc.) are enforced by PDF viewers, and well-behaved viewers respect them — but they are not unbreakable DRM. The open password requirement itself, however, is real encryption: without a password the content cannot be read.
What happens if I forget the passwords?
There is no recovery. Nothing is stored on any server — that's the point — so a lost password means a permanently locked file. Keep the owner password in a password manager and always retain your original unencrypted copy somewhere safe.
Is my password sent anywhere when I use this tool?
No. Encryption runs in a local browser worker; the file bytes and both passwords exist only in your tab's memory during processing. You can disconnect from the internet before clicking Protect and it still works.
Privacy note: like every Novus PDF Studio tool, protectruns entirely in your browser. Files, passwords, and settings stay in this tab's memory and are discarded when you close it — there is no upload, no queue, and no server-side copy. Read more on the privacy page.