Code to Protect PDF with Password in Java. For more information, please follow link: https://kb.conholdate.com/total/java/how-to-protect-pdf-with-password-in-java/

how-to-protect-pdf-with-password-in-java.java

import com.aspose.pdf.CryptoAlgorithm;
import com.aspose.pdf.Document;
import com.aspose.pdf.License;

public class ProtectPDFWithPasswordInJava {
	public static void main(String[] args) throws Exception { // main method to protect PDF with password in Java

	// Instantiate the license to avoid trial version limitations and watermark in the protected PDF
	License asposePdfLicenseProtect = new License();
	asposePdfLicenseProtect.setLicense("Aspose.pdf.lic");

	// Open document
	Document documentToProtect = new Document("Input.pdf");

	// Encrypt PDF
	documentToProtect.encrypt("user", "owner", com.aspose.pdf.facades.DocumentPrivilege.getForbidAll(), CryptoAlgorithm.RC4x128 , false);

	// Save updated PDF
	documentToProtect.save("Password PDF.pdf");

	System.out.println("Done");
 }
}