About Protect PDF
Protect PDF encrypts a PDF with a password. Anyone who opens the file needs the password, whether they use Adobe Reader, a browser, a phone or a Mac's Preview app.
Encrypt payslips, medical reports, tax returns, bank statements and contracts before you email them or store them in cloud folders that other people can reach. Encryption protects the file even if an email gets forwarded to the wrong person or a laptop goes missing.
The tool uses AES-256, the strongest encryption the PDF standard supports, and lets you decide whether readers can print, copy text or edit the document.
How to use Protect PDF
- Open the PDF you want to protect.
- Type a password and repeat it.
- Set permissions for printing, copying and editing.
- Optionally set a separate owner password.
- Click Protect PDF and download the encrypted file.
AES-256 encryption
The strongest standard PDF encryption, supported by all current PDF readers.
Permission control
Allow or block printing, copying and editing.
Password strength meter
See right away whether your password is weak or strong.
No upload
The password and the document stay on your device. We never see either.
User password, owner password and permissions
A PDF can have two passwords. The user password (also called the open password) is needed to open the document. The owner password (also called the permissions password) is needed to change the document's security settings. This tool always sets a user password. If you leave the owner password empty, the tool uses the same password for both.
Permissions tell PDF readers what someone who opened the file with the user password may do: print, copy text, or edit and fill forms. Mainstream readers such as Adobe Acrobat, Chrome and Preview respect these flags. Treat them as a polite request, though. Anyone who can open a document can, with some effort and the right software, print or copy it anyway. The encryption itself is what keeps out people without the password.
AES-256 encryption scrambles the file's content with a key derived from your password. With a strong password, nobody can open the file by guessing within any practical time. With a weak password, such as a birth date or "123456", tools that test millions of passwords per second can open it in minutes. The strength meter helps you avoid that.
Send the password through a different channel from the file. If you email the PDF, text the password or tell it by phone. Someone who intercepts the email then gets a locked file and nothing more.
Tips for better results
- Use a passphrase of four or more random words, such as "lamp-orbit-cactus-river". It is long, strong and easy to type.
- Keep the password in a password manager. Nobody can recover a lost password from an AES-256 PDF.
- Compress, sign and watermark before protecting. Most tools can't edit an encrypted file.
- For recipients on very old software, test that they can open the file before you send something urgent.
Questions and answers
How secure is the encryption?
AES-256 is the strongest encryption in the PDF standard. Security depends on your password: use at least 12 characters or a passphrase.
Can you recover my password if I forget it?
No. We never see your password or your file. Store the password safely.
Will the recipient need special software?
No. Adobe Reader, browsers, Preview on Mac and phone PDF viewers all open AES-256 PDFs.
Can I remove the password later?
Yes, with Unlock PDF and the password.
Do permissions stop all copying?
Standard readers obey them, but determined users with special software can bypass permissions. Only the open password provides real protection.