How to Password Protect a PDF File using Java

PDF (Portable Document Format) files are widely used for sharing documents due to their platform-independent nature and consistent formatting. However, some documents may contain sensitive information that requires an extra layer of security. If you are a Java developer, you can easily accomplish this task programmatically using Apache PDFBox. Apache PDFBox library is open source and free library for both commercial and non commercial use.

In this blog post, we’ll dive into how you can use Java and Apache PDFBox to add password protection to a PDF file.

Prerequisites

Before we begin, ensure you have the following in place:

1. Java Development Kit (JDK): Ensure that you have JDK installed on your system. If not, you can download it from here.
2. A Java IDE (Integrated Development Environment) like Eclipse or IntelliJ IDEA os Microsoft VS Code.

1: Set Up the Project

Create a new Java project in your IDE and add the Apache PDFBox library to the project’s build path. If you are using Maven or Gradle to manage the dependencies, you can integrate the Apache PDFBox to your project by including the dependencies to your pom.xml or build.gradle file.

If you are using Maven, you can add the following dependency in your pom.xml file to include Apache PDFBox.

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>3.0.0</version>
</dependency>

If you are using Gradle, you can add the below dependency,

implementation("org.apache.pdfbox:pdfbox:3.0.0")

Also Read: How to Create Immutable Objects in Java

2: Load the PDF Document

Now let’s look into how we can add password protection to an existing PDF file. To start, you need to load the PDF document you want to protect using the PDDocument class from the PDFBox library.

import org.apache.pdfbox.Loader;
import org.apache.pdfbox.pdmodel.PDDocument;

try {
    String inputFilePath = "input.pdf"; // Replace with the path to your input PDF file
    PDDocument document = Loader.loadPDF(new File(inputFilePath));
    // Your code to password protect the document will go here
    document.close();
} catch (IOException e) {
    e.printStackTrace();
}

import org.apache.pdfbox.pdmodel.encryption.AccessPermission;
import org.apache.pdfbox.pdmodel.encryption.StandardProtectionPolicy;

String userPassword = "your_user_password"; // Replace with your desired user password
String ownerPassword = "your_owner_password"; // Replace with your desired owner password

AccessPermission accessPermission = new AccessPermission();
accessPermission.setCanPrint(false); // Set to true if you want to allow printing

StandardProtectionPolicy protectionPolicy = new StandardProtectionPolicy(ownerPassword, userPassword, accessPermission);

document.protect(protectionPolicy);

String outputFilePath = "output.pdf"; // Replace with the desired path for the output protected PDF file

try {
    document.save(outputFilePath);
    System.out.println("PDF file is password protected successfully!");
} catch (IOException e) {
    e.printStackTrace();
}