Password Protect a PDF — AES-256 Encryption

What you can do

• •Add an AES-256 open password so the PDF cannot be read without it
• •Choose whether readers are allowed to print or copy text
• •Protect sensitive attachments before email or chat sharing
• •Apply protection locally in the browser
• •Use unlock later when you need to remove a known password

How it works

1. 1

   Select your PDF

   Choose the file from your device.

2. 2

   Set a password

   Choose an open password. AES-256 protection is applied locally.

3. 3

   Download

   Save the protected PDF.

Common uses

• •Password-protect financial statements before emailing
• •Lock a PDF resume pack shared over public links
• •Restrict editing on a contract draft you still want others to read
• •Secure homework or medical PDFs on shared devices

Frequently asked questions

What encryption is used?

Open-password protection with AES-256 applied on-device.

Will I need the password to open the file later?

Yes. Anyone opening the protected PDF — including you — needs the password you set. There is no recovery or reset here, so store it safely.

Can I stop people printing or copying the text?

You can turn printing and copying off when you protect the file. These are permission flags in the PDF, so well-behaved readers respect them, but they are weaker than the open password — that password is what actually keeps the content unreadable.

Can I protect a PDF that already has a password?

Not directly. Remove the existing password with Unlock PDF first, then protect the file again with the password you want.

Protect vs unlock — how do they relate?

Protect adds an open password. Unlock removes a password when you already know it.

Is my password sent to a server?

No. Encryption is performed in the browser.

Related PDF tools

• Unlock PDF
• Remove Metadata
• Compress PDF
• All PDF tools