How to Password-Protect a PDF (and Remove the Password Later)

A PDF is often the format people choose for things they do not want to change: contracts, invoices, scanned IDs, medical letters and bank statements. It is also a format that gets emailed, uploaded and left in download folders. A password stops the wrong person opening the file if it ends up somewhere it should not. This guide explains what PDF passwords really do, how to add one without uploading your document anywhere, and how to remove it again.

Two different kinds of PDF password

The PDF format has two passwords, and they do very different jobs.

• The open password (also called the user password) is required to open the file at all. Without it the contents are scrambled. This is the one that protects your privacy.
• The permissions password (the owner password) lets people open the file but asks the viewer to block printing, copying text or editing. It can be removed without knowing the password in many programs, because it is a request that PDF apps agree to respect rather than a lock.

How to add a password to a PDF

1. Open the PDF Password Protector and choose your PDF. The file is processed on your own device and is never uploaded.
2. Type the password twice. Use at least 12 characters if the document is sensitive.
3. Tick "restrict what people can do" only if you also want to block printing, copying or editing, and set a different owner password if you do.
4. Click Protect PDF. The tool reads the new file back to confirm that it really needs the password before it lets you download it.

How strong is the protection?

The tool encrypts with AES-256, the strongest encryption method the PDF standard offers. With a long, random password, breaking it by guessing is not realistic. The weak point is almost always the password itself. A short or predictable password such as a birthday, a pet's name or a word from a dictionary can be guessed quickly by software, whatever the encryption strength.

• Use a long password, at least 12 characters, ideally random.
• Use a different password for every sensitive document.
• Send the password through a different channel from the file, for example by phone or message rather than in the same email.

What password protection does not do

• It does not hide the fact that the file exists or its file name.
• It cannot stop someone who has the password from copying or sharing the contents.
• Permission restrictions do not stop a screenshot or a photograph of the screen.
• It cannot be recovered if you forget the open password. There is no reset link.

How to remove a PDF password

If you know the password, open the Unlock PDF tool, choose the file and enter the password. You get an unprotected copy, and the tool checks that the new file opens freely.

If the PDF opens without a password but will not let you print or copy, it only has permission restrictions. The Unlock PDF tool can remove those without a password. Use this only on documents you own or are allowed to open. The tool does not guess or crack passwords, and a wrong password is reported clearly.

Common mistakes

• Choosing a password that is easy to remember but easy to guess.
• Emailing the password in the same message as the PDF.
• Relying on "no copying" or "no printing" restrictions to keep something secret.
• Protecting the only copy of a document and then losing the password.

Ready to try it? Open the PDF Password Protector, or if a PDF is too large to email once it is protected, shrink it first with Compress PDF.