For PDF documents that contain confidential or sensitive information, you may want to password protect these documents to ensure that only the designated person can access the information. This article will demonstrate how to programmatically encrypt a PDF document and decrypt a password-protected document using Spire.PDF for Java.
Install Spire.PDF for Java
First of all, you're required to add the Spire.Pdf.jar file as a dependency in your Java program. The JAR file can be downloaded from this link. If you use Maven, you can easily import the JAR file in your application by adding the following code to your project's pom.xml file.
<repositories>
<repository>
<id>com.e-iceblue</id>
<name>e-iceblue</name>
<url>https://repo.e-iceblue.com/nexus/content/groups/public/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>e-iceblue</groupId>
<artifactId>spire.pdf</artifactId>
<version>12.3.9</version>
</dependency>
</dependencies>
Encrypt a PDF File with Password
There are two kinds of passwords for encrypting a PDF file - open password and permission password. The former is set to open the PDF file, while the latter is set to restrict printing, contents copying, commenting, etc. If a PDF file is secured with both types of passwords, it can be opened with either password.
The PdfDocument.getSecurity().encrypt(java.lang.String openPassword, java.lang.String permissionPassword, java.util.EnumSet<PdfPermissionsFlags> permissions, PdfEncryptionKeySize keySize) method offered by Spire.PDF for Java allows you to set both open password and permission password to encrypt PDF files. The detailed steps are as follows.
- Create a PdfDocument instance.
- Load a sample PDF file using PdfDocument.loadFromFile() method.
- Set open password, permission password, encryption key size and permissions.
- Encrypt the PDF file using PdfDocument.getSecurity().encrypt(java.lang.String openPassword, java.lang.String permissionPassword, java.util.EnumSet<PdfPermissionsFlags> permissions, PdfEncryptionKeySize keySize) method.
- Save the result file using PdfDocument.saveToFile () method.
- Java
import java.util.EnumSet;
import com.spire.pdf.PdfDocument;
import com.spire.pdf.security.PdfEncryptionKeySize;
import com.spire.pdf.security.PdfPermissionsFlags;
public class EncryptPDF {
public static void main(String[] args) {
// Input file path
String input = "data/encryption.pdf";
// Output file path
String output = "output/encryption_output.pdf";
// Create a new PDF document object
PdfDocument doc = new PdfDocument();
// Load the PDF document from the input file path
doc.loadFromFile(input);
// Create a password-based security policy with open and permission passwords
PdfSecurityPolicy securityPolicy = new PdfPasswordSecurityPolicy("openPwd", "permissionPwd");
// Set the encryption algorithm to AES 256-bit
securityPolicy.setEncryptionAlgorithm(PdfEncryptionAlgorithm.AES_256);
// Set document privilege to forbid all actions
securityPolicy.setDocumentPrivilege(PdfDocumentPrivilege.getForbidAll());
// Allow degraded printing
securityPolicy.getDocumentPrivilege().setAllowDegradedPrinting(true);
// Allow modification of annotations
securityPolicy.getDocumentPrivilege().setAllowModifyAnnotations(true);
// Allow document assembly
securityPolicy.getDocumentPrivilege().setAllowAssembly(true);
// Allow modification of document contents
securityPolicy.getDocumentPrivilege().setAllowModifyContents(true);
// Allow filling form fields
securityPolicy.getDocumentPrivilege().setAllowFillFormFields(true);
// Allow printing
securityPolicy.getDocumentPrivilege().setAllowPrint(true);
// Allow printing
doc.encrypt(securityPolicy);
// Save the encrypted document to the output file path
doc.saveToFile(output, FileFormat.PDF);
// Dispose of the document resources
doc.dispose();
}
}
Remove Password to Decrypt a PDF File
When you need to remove the password from a PDF file, you can set the open password and permission password to empty while calling the PdfDocument.getSecurity().encrypt(java.lang.String openPassword, java.lang.String permissionPassword, java.util.EnumSet<PdfPermissionsFlags> permissions, PdfEncryptionKeySize keySize, java.lang.String originalPermissionPassword) method. The detailed steps are as follows.
- Create a PdfDocument object.
- Load the encrypted PDF file with password using PdfDocument.loadFromFile(java.lang.String filename, java.lang.String password) method.
- Decrypt the PDF file by setting the open password and permission password to empty using PdfDocument.getSecurity().encrypt(java.lang.String openPassword, java.lang.String permissionPassword, java.util.EnumSet<PdfPermissionsFlags> permissions, PdfEncryptionKeySize keySize, java.lang.String originalPermissionPassword) method.
- Save the result file using PdfDocument.saveToFile() method.
- Java
import com.spire.pdf.PdfDocument;
import com.spire.pdf.security.PdfEncryptionKeySize;
import com.spire.pdf.security.PdfPermissionsFlags;
public class DecryptPDF {
public static void main(String[] args) throws Exception {
// Specify the input and output file paths
String input = "data/decryption.pdf";
String output = "output/decryption_result.pdf";
//load the pdf document.
PdfDocument doc = new PdfDocument();
doc.loadFromFile(input, "test");
//decrypt the document
doc.decrypt();
//save the file
doc.saveToFile(output, FileFormat.PDF);
// Close the PDF document to release resources
doc.close();
// Dispose of the PDF document to free up system resources
doc.dispose();
}
}
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