Create a pdf file using java and encrypt / decrypt it.

For this example to work you will need following jar files.

1. bcpkix-jdk15on-1.47.jar
2. itextpdf-5.1.0.jar
3. bcprov-jdk14-146.jar

Download them and include them in your project classpath.

 /*  
  * This class is part of the book "iText in Action - 2nd Edition"  
  * written by Bruno Lowagie (ISBN: 9781935182610)  
  * For more info, go to: http://itextpdf.com/examples/  
  * This example only works with the AGPL version of iText.  
  */  
 import java.io.FileOutputStream;  
 import java.io.IOException;  
 import com.itextpdf.text.Document;  
 import com.itextpdf.text.DocumentException;  
 import com.itextpdf.text.Paragraph;  
 import com.itextpdf.text.pdf.PdfWriter;  
 import com.itextpdf.text.pdf.PdfReader;  
 import com.itextpdf.text.pdf.PdfStamper;  
 public class EncryptionPdf {  
   /** User password. */  
   public static byte[] USER = "Hello".getBytes();  
   /** Owner password. */  
   public static byte[] OWNER = "World".getBytes();  
   /** The resulting PDF file. */  
   public static final String RESULT1  
     = "F:/encryption.pdf";  
   /** The resulting PDF file. */  
   public static final String RESULT2  
     = "F:/encryption_decrypted.pdf";  
   /** The resulting PDF file. */  
   public static final String RESULT3  
     = "F:/encryption_encrypted.pdf";  
   /**  
    * Creates a PDF document.  
    * @param filename the path to the new PDF document  
    * @throws DocumentException   
    * @throws IOException   
    */  
   public void createPdf(String filename) throws IOException, DocumentException {  
     // step 1  
     Document document = new Document();  
     // step 2  
     PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(filename));  
     writer.setEncryption(USER, OWNER, PdfWriter.ALLOW_PRINTING, PdfWriter.STANDARD_ENCRYPTION_128);  
     writer.createXmpMetadata();  
     // step 3  
     document.open();  
     // step 4  
     document.add(new Paragraph("Hello World"));  
     // step 5  
     document.close();  
   }  
   /**  
    * Manipulates a PDF file src with the file dest as result  
    * @param src the original PDF  
    * @param dest the resulting PDF  
    * @throws IOException  
    * @throws DocumentException  
    */  
   public void decryptPdf(String src, String dest) throws IOException, DocumentException {  
     PdfReader reader = new PdfReader(src, OWNER);  
     PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));  
     stamper.close();  
     reader.close();  
   }  
   /**  
    * Manipulates a PDF file src with the file dest as result  
    * @param src the original PDF  
    * @param dest the resulting PDF  
    * @throws IOException  
    * @throws DocumentException  
    */  
   public void encryptPdf(String src, String dest) throws IOException, DocumentException {  
     PdfReader reader = new PdfReader(src);  
     PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));  
     stamper.setEncryption(USER, OWNER,  
       PdfWriter.ALLOW_PRINTING, PdfWriter.ENCRYPTION_AES_128 | PdfWriter.DO_NOT_ENCRYPT_METADATA);  
     stamper.close();  
     reader.close();  
   }  
   /**  
    * Main method.  
    *  
    * @param  args  no arguments needed  
    * @throws DocumentException   
    * @throws IOException  
    */  
   public static void main(String[] args) throws IOException, DocumentException {  
     EncryptionPdf metadata = new EncryptionPdf();  
     metadata.createPdf(RESULT1);  
     metadata.decryptPdf(RESULT1, RESULT2);  
     metadata.encryptPdf(RESULT2, RESULT3);  
   }  
 }