How can I add password to PDF for protection from Windows 11?

Preview is a PDF and image viewing/editing tool that comes with macOS and supports adding password protection to PDFs without installing additional software. It is suitable for quickly encrypting PDF files and supports simple PDF editing, signing, and merging.

You can create a new Mac virtual machine and start password protecting PDF with the free Preview app.

How to add password to PDF on Mac virtual machine

1. Click "File" → "Export to PDF" on the top menu bar.
2. In the pop-up window, click the "Encrypt" option (if there is no such option, the macOS version may be too old).
3. Enter the password you want for the PDF in the "Confirm password" field, and re-enter the same password
4. Click "Store", choose the file save location. This will add password to PDF without any tool.
5. Find the encrypted PDF file just saved, double-click to open.
6. The system will pop up the password input box, enter the password and click "OK".
7. If the password is correct, the PDF will be unlocked. If it is incorrect, you can not view the content.