How to password-protect a PDF
A password can do two different jobs on a PDF: stop people opening it at all, or let them read it while limiting what they can do with it. Knowing which you need is most of the work.
Open Protect PDFEncrypt your PDF with a password and control printing and copying.
The two passwords
- Open password: anyone who opens the file is asked for it. Without it the document cannot be read. Use this for confidential documents.
- Owner password: controls permissions such as printing, copying and editing. On its own it lets anyone read the file while the restrictions apply. This is the usual choice for a document you publish.
You can set either one or both. If they are the same, every reader holds the key to the restrictions too, so they become advisory only.
Protect a PDF step by step
- Open Protect PDF and add your file.
- Set an open password, an owner password, or both (at least 4 characters each; longer is much safer).
- Choose what readers may do: print (at full or draft quality, or not at all), copy text, edit, add comments, fill in forms, rearrange pages, and allow screen readers.
- Select Protect and download the protected PDF.
The file is encrypted with AES-256, using the method set out in the current PDF standard (PDF 2.0), which current PDF readers support.
Good practice
- Send the password separately, by message or phone, never in the same email as the file.
- Treat permissions as a request, not a lock. Standard readers respect them, but some software ignores them. Only the open password actually keeps people out.
- Leave screen-reader access on unless you have a specific reason to block it; many organisations are required to keep documents accessible.
- To remove information entirely, use Redact PDF rather than a password. A password hides the whole file; redaction removes the sensitive part for good.
To take the protection off later, use Unlock PDF with the password. It only works on files you know the password for: Papermint never bypasses protection.