How to Secure a PDF Document Using PDFpen

Securing PDF documents is important. When you don’t secure a PDF, you risk other people seeing, printing, modifying, sharing, and leaking your (or your customers') information. You don’t need to work for a spy agency to care: no matter what your job or industry, a data breach is always bad. So how do you protect your PDFs? PDFpen has two handy features you can use: redaction and password protection.

Redaction is the process of deleting text for security purposes. When sharing a document that contains classified info, it’s always prudent to redact it. Note that true redaction is different from placing a black rectangle over sensitive text, or changing the background of the text to black.

These methods simply hide the text as opposed to permanently removing it. To see it, all someone needs to do is use copy and paste. True redaction—the type you can accomplish with PDFpen—deletes the text and replaces it with blank space or a black box. 

We tested the efficacy of different redaction methods—see How To Redact a PDF: The Best Proven Method.

To redact text using PDFpen, follow these steps:

1. Select the text you want to redact.
2. In the menu, choose Format > Redact text.
3. Choose Redact Text – Block if you want the text blacked out.
4. Choose Redact Text – Erase if you want a blank space in place of the text.

To remove sensitive information that repeats itself throughout a lengthy document, search for it and mark it for automatic redaction:

1. Choose Edit > Find > Find and Redact.
2. Type the text you want to redact.
3. Choose a Redaction Style (Block/Erase).
4. Click “Redact All.”

Encryption, or password protection, helps prevent outsiders from opening or interfering with your documents. There are two types of passwords you can set:

• A user password restricts access to the PDF
• An owner password allows access to the PDF but restricts modifying, copying, saving, or printing. 

When you set a user password, you restrict access. When you set an owner password, you manage permissions. One single PDF can have both types of passwords.

To set a user password, follow these steps:

1. Choose File > Duplicate (Command+Shift+S). In the new document, choose File > Save (Command+S). Or use File > Save As (Command+Option+Shift+S).
2. At the bottom of the Save dialog, select an Encryption option. We recommend Strong.
3. Enter a password in the Password field.
4. Re-enter the same password in the Verify field.
5. Click Save.

To set an owner password, follow these steps:

1. Open the Inspector window to and select the Document Permissions tab by clicking on the lock icon. 
2. Click the Add button. A pop-up window will appear. 
3. Enter a password in the Password field, and then re-enter it in the Verify field. Click OK to finish.
4. Select your permissions. 
5. Choose File > Save to apply these settings.

Note: The default encryption of document permissions is AES-128. To change this, add a user password. The permissions encryption will take on the same encryption level as the user password. 

Password-protecting a PDF document doesn’t make it 100% secure. With time and dedication, a hacker can crack PDF encryption. There are also PDF editing applications out there that actually don’t respect user permissions. That’s definitely not the case with trustworthy PDF editing applications such as Adobe Reader, Preview, and PDFpenPro.

Does that mean setting passwords is useless? Not at all. As Michael E. Cohen says, “Just because someone can smash in a locked door is no reason to prop the door open.”

When it comes to securing a PDF, it's helpful to think in terms of layers. Setting a password to a PDF file means adding one layer of security to the document. We recommend adding more than one layer of security to classified documents. For example, you may want to redact sensitive information in it in addition to restricting access and setting user permissions.

To try redaction and encryption at no charge for 30 days, download a free trial.