Require a password to open a PDF

To make a PDF ask for a password before showing its contents, use a document open password. A permissions password controls actions such as printing, editing, copying, and commenting after the file opens. Choosing only Permissions will not meet the goal of requiring a password to open the file. Adobe explains the two settings.

Set the password in Acrobat

Open the PDF and select All tools > Protect a PDF. In the left panel, under Advanced Options, choose Encrypt with Password, then select Yes in the dialog. Select Require a password to open the document, enter a password in Document Open Password, and select OK. Re-enter the password when prompted, acknowledge the security message, and save the PDF. The save step applies the change in Adobe’s procedure.

Check the file you will send

Close the PDF and reopen the saved file you intend to share. It should request a password before displaying the page. Check that the correct password opens it; if you have multiple copies, confirm the name and location of the one you tested.

If that file opens without a prompt, it has failed this check. Return to the document open setting, save the change, and test the resulting file again. A setting visible before saving, or a successful check of another copy, does not establish how the file you send will behave. This check addresses opening access; it does not establish restrictions on printing, editing, copying, or commenting.

Field note: synthetic PDF check

A separate, synthetic one-page PDF was encrypted with a user/open password using pypdf 6.10.0 and AES-256. On reopening it, PdfReader reported is_encrypted=true. decrypt('incorrect') returned 0; the correct password returned 1, after which the page text was readable. Poppler also rendered the page when supplied the open password.

That result shows the tested pypdf-created file resisted the incorrect password in those tools and opened with the correct one. It does not test Acrobat’s menu procedure or compatibility with a recipient’s PDF viewer.

Source and verification: Adobe’s two pages were reviewed on 2026-09-29 for the Acrobat instructions. The hands-on result above comes only from the synthetic pypdf file; no Acrobat-created PDF was tested for this guide.