How to Password Protect a PDF on Mac

Let’s say you have a $250,000 contract to manage. It includes critical financial information—and personal information like names and dates. Bank information, social security numbers, you name it. If you leave these unprotected, you can become an easy target for identity thieves.

It’s not exactly something that you’d want floating freely on the Internet. Yet many people don’t take the small time investment to password protect their PDFs.

For many, the reason is simple. They don’t know how. It’s also frustrating figuring out how to do so if it’s Windows or Mac. To simplify things, we can show you. Here’s how you can password protect a PDF on Mac - devices without pulling out your hair.

First things first: PDF management is far easier when you have reliable software you can use. We recommend Nitro PDF Pro for Mac. It makes handling PDFs easy.

And once you know how to do it, adding a password to your PDF file will seem laughably simple. Here’s what you’ll need to do.

First, you’ll need to choose between two key options. To create a user password on the document, you’ll create a password multiple people can know to view the document. If you want someone to be able to change document permissions, then you would go the owner password route.

Setting a User Password within Nitro PDF Pro for Mac

If you’re letting people view, but not modify, the PDF, you’ll want to set a user password. Here are the basic steps:

• Open the file you want to password protect.
• Go to File -> Duplicate (Command + Shift + S on Mac). 
• In the new file, use File -> Save or Command + S to save.
• This will open a “Save dialog.” At the bottom of this dialog, you can select an encryption option. Choose Strong.
• Enter a password into the password field. 
• Re-enter the password when it requests that you verify your password.
• Click Save.

Now what happens? Essentially, the file will work just like any other file you have. You can send it for signatures, for example. However, to open the file and view it, the user will be prompted to enter the password, which you will have to provide.

Understanding the Different Encryption Levels
If you read through the above but haven’t tried it out yet, you’ll notice that we recommended that you choose “Strong” as your encryption level within the Save dialog.

Why “Strong”? Here’s what you’ll need to know about each encryption level:

• Weak: This is a 40-bit RC-4 encryption level. Anyone with a regular PDF viewer will be able to view the file, which is why you’ll need to select a stronger level to activate the password protection.
• Strong: This is 128-bit AES encryption. With this enabled, users of Nitro PDF Pro for Mac v4.2 and later will be able to view it, as will people with Adobe Reader 7 and later. In macOS 10.5 and later, people will be able to see it in Preview. This will enable a password.
• Strongest, Least Compatible: 256-bit AES encryption. This is the highest level and will activate compatibility requirements that can sometimes be difficult for every user to meet. For this reason, you’ll generally select “Strong” to get reasonable levels of encryption for your password-protected document.

Removing a User Password
What happens if you change your mind about the level of security you need with a PDF? This is when you’ll want to think about removing the requirement that a user enter a password to view it.

• Go to File -> Duplicate or Command + Shift + S. 
• In the new document you’ve created, do File -> Save or Command + S.
• This will bring up the Save dialog.
• At the bottom of the Save dialog, you’ll see the list of encryption options again. This time, select Weak. 
• Click Save.

By now, you should have a pretty clear idea of how you can password protect (or un-protect) your PDFs on a Mac. Within Nitro PDF Pro for Mac, it’s simply a matter of setting different encryption levels. To go from a password-protected PDF to an unprotected file, you can simply change out Strong to Weak. Or, to go back, you can do the reverse.

Thus far, we’ve talked about user passwords: the passwords people need to simply view a PDF, perhaps for signing a contract. But what if you want to protect the ability to edit permissions on the PDF itself? What do you do then?

Now we’re talking about adding an owner password. And since this is a more advanced tool within Nitro PDF Pro for Mac, it’s worth addressing in its own section.

For starters, you can refer to the Document Permissions section of Nitro PDF Pro for Mac. However, we’ll also break it down into simple steps so that you can refer to this page whenever you need to add or remove permissions.

• Open the Inspector window on your PDFpen program. To do this, click the Inspector button in the toolbar .

  

  On Macs, you can also use Command + Option + I to open the Inspector window.
• Click the Add button.
• This will bring up the “Enter Owner Password” section, as seen below. You’ll have to enter a password and then re-enter the password again to verify that it’s the correct password.

• Select the permissions you want to set. For a fuller explanation of those permissions, see the section below.
• Go to File -> Save to make these new settings permanent.

The key difference between setting owner security and user passwords is that you’ll have to open the Inspector Window, which is typically not a window you’ll have to work with very often when using Nitro PDF Pro for Mac.

Understanding the Owner Permission Settings
So far, you know how to set an owner password to protect your PDF. But that gives rise to a new question: what kinds of protections are you applying to a PDF when you set that owner password? To answer that, we have to address the specific permissions that will take place.

Under Permission Settings, you’ll be able to select from a wide range of options. Here’s a brief explanation of what those options are, if you want to customize your owner permission settings:

• Print: Simple enough, this lets a user print the PDF if they want. You can also select to Allow high-res printing, although this setting is not recommended. When someone uses high-res printing, it will flatten the PDF, which will negate any permission settings. That’s why it’s probably a good idea to leave this one off.
• Modify any content: Do you want someone to be able to modify content? You may not want to if you simply want someone to be able to view the content. This will include options for modifying pages, filling forms, and even annotating the documents.
• Modify pages: Being able to reorder, copy, and even delete pages all fall under the umbrella of “modify pages.”
• Copy text and objects: Just like it sounds, this lets someone copy document content directly outside the document. Leave it off if you want to minimize content sharing.
• Fill forms: Choose whether or not a user can fill in form fields.
• Annotate documents: Want someone to add comments, notes, highlights, and markups? Make sure this permission is enabled.

There are other permissions you can view at our guide to advanced features and document permissions. Before you start using them, try tinkering with the software in contracts that you don’t have to use professionally yet. This will help you better understand how sharing, password protection, and more all work. And if you sign up for a free trial of Nitro PDF Pro for Mac, you can immediately begin learning all that you can do with a PDF when you use reliable software.