How to password-protect a PDF

Payslips, medical letters, contracts, bank statements — some PDFs shouldn’t be readable by whoever happens to see an email or a shared folder. A password fixes that: without it, the file can’t be opened.

How to add a password to a PDF

1. Open Protect PDF and select the file.
2. Enter a password and type it again to confirm.
3. Choose what people who open it may do: print, copy text and images, or edit and fill forms.
4. Click Protect PDF and download the encrypted file.

The file is encrypted with AES-256, the strongest encryption the PDF format supports. Every major PDF reader — Adobe Acrobat, Chrome, Edge, Preview, phone viewers — will ask for the password before showing it.

Choosing and sharing the password

• Length beats complexity. Three or four random words (like “river-lamp-cotton-seven”) are strong and easy to type.
• Send it separately. If you email the PDF, send the password by text message or tell it by phone. Putting both in the same email defeats the purpose.
• Keep a copy. A lost password can’t be recovered — not by PDFfinch, and not by anyone else.

Removing the password later

If you get tired of typing the password, Unlock PDF removes it — you’ll need to enter it once. It can also remove restrictions on printing and copying from PDFs that open without a password.

Restrictions on printing and copying are a polite request that most readers respect, not strong protection. The open password is what actually keeps people out.