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How To Password Protect A PDF Document

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By: Nihad Hassan

August 3, 2021

In today's digital age, most information is created digitally and never finds its way into papers. Organizations of all types and across all industries are utilizing PDF documents in their daily work to store a variety of business-related information (e.g., customer, suppliers, third-party contractors, and tax info, to name only a few). Many global organizations use the PDF standard as the only acceptable format when exchanging files with other external parties.

Sometimes, we may need to send a PDF file containing sensitive information such as our social security number, passport copy, tax information, healthcare info, or other financial information. We do not need this info to fall in the wrong hand during the transit. The same security risk applies when storing sensitive PDF files in a USB drive. We can password-protect (encrypt) the PDF file so only intended users can open it to solve this obstacle.

Comparable with MS Office, which offers a built-in password protection feature, the standard free version of Adobe Acrobat lacks such a feature. Nevertheless, this should not prevent you from utilizing the password protection feature as there are many programs –and free online services- to password your sensitive PDF files.

This article will demonstrate how to protect your PDF file using the commercial version of Adobe Acrobat; we will also use a third-party tool to conduct the same task.

Adobe Acrobat

To protect your PDF files using the commercial version of Acrobat, follow these steps:

"We are using Adobe Acrobat X version 10.0 for this experiment."

  1. Open the PDF file you want to protect.
  2. Go to View >> Tools >> Protection (see Figure 1).
  3. The tool pane appears on the right side of the Acrobat window. Select Encrypt >> Encrypt with Password... (See Figure 2).
Access Tools pan
Figure 1: Access Tools pan under Acrobat Reader version 10.00
Encrypt with Password
Figure 2: Encrypt with Password
Figure 2 - Encrypt with Password
  1. The Password window appears; leave the default settings as it is, and make sure to enter a strong password to protect your PDF file (see Figure 3). Keep in mind; the password is needed to open the file next time, so keep it in a safe place.
Enter a strong password
Figure 3: Enter a strong password to secure your PDF file
  1. Click the "OK" button, and Adobe will display another pop-up window asking you to confirm the password again (see Figure 4). After hitting the "OK" button, Adobe will display a warning message stating that the security settings will not be applied until saving the document (see Figure 5).
Confirm PDF password dialog box
Figure 4: Confirm PDF password dialog box
saving file
Figure 5: Current file must be saved first before applying the new security settings – Click "OK" then save the file

Now, you need to find a secure method to send the password to the recipient so that he/she can open the password-protected PDF file. Utilizing Gpg4Win (a free open source file and email encryption utility) is an excellent choice to send an encrypted message containing the secret password.

Now when anyone wants to open the password-protected file, Acrobat –or other PDF readers- will display a new window asking for a password to gain access (See Figure 6). using the correct password

Figure 6: Anyone who wants to access the password-protected file must provide the correct password first

How to remove the password from the PDF-protected file?

Open the PDF password-protected file, then click on the Lock icon on the upper left >> Select "Permission Details" (see Figure 7). Access PDF file security settings

Figure 7: Access PDF file security settings

Click the "Change settings" as appears in the above figure, the password security settings appear, remove the checkmark from "Require a password to open the document" (see Figure 8). You need to save the file after Adobe prompts you to apply the new security settings. Remove password from a password protected PDF file

Figure 8: Remove password from a password protected PDF file


PDFEncrypt is a free, open-source tool for encrypting PDF files using the standard PDF encryption algorithms. It runs on Windows operating systems and uses the iTextPDF open-source library to perform the encryption routine. PDFEncrypt has a simple interface with few options to encrypt and decrypt PDF files.

To encrypt a PDF file, select the file you want to encrypt, then choose the destination to save the new –encrypted- file. PDFEncrypt will append the "encrypt" extension to the file's encrypted version (see Figure 9). PDFEncrypt tool

Figure 9: PDFEncrypt tool

The "Settings…" (See Figure 10) window in PDFEncrypt offers additional options, such as encrypting the PDF file metadata, in addition to various settings for restricting the subject file editing functions. PDFEncrypt settings window

Figure 10: PDFEncrypt settings window


The PDF file format was first invented in 1991; the file format was initially named Camelot Project; nevertheless, in 1992, the name changed to PDF. After one year, Adobe released its popular free Acrobat Reader to read PDF files across all major platforms.

PDF has become a global standard for exchanging documents; the most notable advantage of PDF appeared when the USA Internal Revenue Service began to use it solely to receive tax forms, reducing the need for papers to submit the relative tax forms.

This article shed light on how we can secure PDF files using the commercial version of Adobe Reader, and we also introduced a free open source tool for conducting the same task for free. There are many free online services for password protecting your PDF files. However, it is not advisable to utilize such services, as uploading sensitive files to remote servers is not safe.

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