If you want to restrict access to a PDF document, one way to do this is by setting a password on it. Thanks to OS X’s built-in PDF creation tools, it’s relatively straightforward on OS X to add a password to an existing PDF document, or include a password as part of the process of creating a PDF. For more details on this process, see below the jump.
Adding a password to an existing PDF document
Apple has an existing KBase article describing the process of password-protecting a PDF:
1. Open the PDF you want to password-protect in Apple’s Preview.
2. Under the File menu, select Export…
3. Check the Encrypt checkbox.
4. Type the password you want to use to protect the PDF, then retype it to verify.
5. Once finished entering the password, choose the filename for the password-protected PDF and then click the Save button.
Adding a password as part of creating a PDF from a document
The process is slightly different if you want to create a PDF from a non-PDF document and add a password as part of the PDF creation process.
1. Open the document from which you want to create a password-protected PDF.
2. Under the File menu, select Print…
3. In the Print window, select the PDF drop-down menu.
4. In the PDF menu, select Save as PDF…
5. In the next window, select Security Options…
6. Check the box for Require password to open document.
7. Type the password you want to use to protect the PDF, then retype it to verify.
8. Once finished entering the password, click the OK button.
9. Choose the filename for the password-protected PDF and then click the Save button.
Once the password-protected PDF has been created, it should appear with a lock icon as part of the file icon.
Now that the PDF has been password-protected, you should be prompted to enter a password before being given access to the contents of the PDF.
Here’s how it should appear in Apple Preview:
Here’s how it should appear in Adobe Acrobat Reader DC:
