PdfEncryption.java

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.encryption.AccessPermission;
import org.apache.pdfbox.pdmodel.encryption.StandardProtectionPolicy;
import java.io.File;
import java.io.IOException;

class PdfEncryption {
	public static void main(String[] args)
		throws IOException
	{
		// step 1. Loading the pdf file
		File f = new File("D:\\demo.pdf");
		PDDocument pdd = PDDocument.load(f);

		// step 2.Creating instance of AccessPermission
		// class
		AccessPermission ap = new AccessPermission();

		// step 3. Creating instance of
		// StandardProtectionPolicy
		StandardProtectionPolicy stpp
			= new StandardProtectionPolicy("abcd", "abcd", ap);

		// step 4. Setting the length of Encryption key
		stpp.setEncryptionKeyLength(128);

		// step 5. Setting the permission
		stpp.setPermissions(ap);

		// step 6. Protecting the PDF file
		pdd.protect(stpp);

		// step 7. Saving and closing the the PDF Document
		pdd.save("D:\\demo.pdf1");
		pdd.close();

		System.out.println("PDF Encrypted successfully...");
	}
}