How to password protect a PDF document

Password protecting PDF files is easy. We'll show you how.

Confidential PDF documents can be protected with a password. Only people who know the password will be able to open and view those documents.

At the same time, password protected documents are always encrypted, and therefor protected from unauthorized access.

Let's see how password protecting a PDF document works.

Open the unprotected file in PDF Annotator.

Open unprotected file in PDF Annotator

On the PDF Annotator menu, select File, Properties.

File, Properties

On the Document Properties dialog, click the Security tab (1).

Under Document Security, click Set Password & Restrictions (2).

Document Security

In the Password Security dialog, check the Require password to open the document option and enter the Password to open document. Repeat the password in the Confirm password field.

Click OK to confirm the new settings.

Document Security: Open Password

Back under Document Security, you can now see that Security changed to Open Password.

Confirm one more time with OK.

Security: Open Password

A notice will explain that the new security settings will only be in effect once you save and re-open the document.

Save and re-open required

So, let's try the password protection.

Save and close the document, then re-open it in PDF Annotator.

When re-opening the document, you will notice that PDF Annotator will now ask for a password.

The same will apply to any other PDF reader. Any PDF software will require the password to be able to decrypt and display (or even print) the document.

Password required

Once you enter the correct password, the document can be displayed.

Password protected document

Removing the password protection

Once you entered the Open Password, you can again go to File, Properties, switch to the Security tab, and review the security settings.

You can even remove the password protection by clicking Remove.

Remove password protection

Disallow removing or altering the password protection

It was probably not your intention to allow anybody who knows the Open Password to remove the password protection from the document.

To disallow removing or altering security settings with just the Open Password, you need to define a separate, second password, the Permissions Password.

Go to File, Properties, switch to the Security tab, and click Modify Password & Restrictions.

Modify Password & Restrictions

In the Password Security dialog, find the Password to change above restrictions field.

This is the PDF document's Permissions Password.

The Permissions Password had been set to the same as the Open Password, when we first created the password protection.

Now, we can enter a separate, different password here.

Enter Permissions Password

Once again, after saving and re-opening the document (important: once again using the Open Password), we can come back to Document Security and try to either Modify Password & Restrictions or Remove the password protection.

Last time we tried this, we could enter those functions without any additional authentication.

But now that we have set up a Permissions Password, we need to enter that password in the Enter password to change restrictions dialog in order to access those functions.

Enter password to change restrictions

Of course, when we want to password protect a document in a way that only we ourselves can remove the password protection again, we can enter the Permissions Password under Password to change restrictions right away when setting up the password protection.

Password to change restrictions

That was easy!

To summarize:

  • We can set up password protection in PDF Annotator on the Security tab under File, Properties.
  • If we want to ensure that only we can remove the password, we need to enter a separate Permissions Password under Password to change restrictions.