iText: password protect a signed pdf file

[pavithra murthy]

hello friend ,

i had written a code to digitally sign a pdf document using itext jar. Once digitally signed ,signature is validated and present in all the pdf pages.

now thing is i am password protecting the pdf in which input i am giving it as signed pdf document ... once i open with the password ,signature is becoming invalid . I think since its getting protected its not able to find the PKC and keystore where i have placed it in the folder where my program is written .
Please could anyone help me out .

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Iterator;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfEncryptor;

import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.AcroFields;
import com.lowagie.text.pdf.PdfPKCS7;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfSignatureAppearance;
import com.lowagie.text.pdf.PdfStamper;
import com.lowagie.text.pdf.*;
//import com.lowagie.text.pdf.DocumentException;

public class pdfsign11{
  public static void main(String args[]) {
try{
KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
ks.load(new FileInputStream("keystore.ks"), "my_password".toCharArray());
String alias = (String)ks.aliases().nextElement();
PrivateKey key = (PrivateKey)ks.getKey(alias, "my_password".toCharArray());
java.security.cert.Certificate[] chain = ks.getCertificateChain(alias);
PdfReader reader = new PdfReader("Z08V3_ICB_RECHNG.PDF");

int nomPage = reader.getNumberOfPages();
			System.out.println("nomPage: "+nomPage);
			for (int i=1; i<=nomPage; i++)
			{

				FileOutputStream fout = new FileOutputStream("signed"+i+".pdf");
				

				//PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0');
				PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0', null, true);
				//PdfStamper.setEncryption(chain,AllowDegradedPrinting,ENCRYPTION_AES);
				PdfSignatureAppearance sap = stp.getSignatureAppearance();
				sap.setCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
				sap.setReason("I'm the author");
				sap.setLocation("Lisbon");
				// comment next line to have an invisible signature
				sap.setVisibleSignature(new Rectangle(100, 100, 200, 200), i, null);
				stp.close();
				reader = new PdfReader("signed"+i+".pdf");
			}
    		for(int i=1;i<=nomPage;i++)
			{
				File fileStr = new File("signed"+i+".pdf");
				if(i!=nomPage)
				{
										fileStr.delete();
				}

				//PdfStamper stamp = new PdfStamper(reader,
				//	new FileOutputStream("outputsigendpf.pdf"));
				//PdfContentByte under = stamp.getUnderContent(1);
				// change the content beneath page 1
				//PdfContentByte over = stamp.getOverContent(1);
				// change the content on top of page 1
				//stamp.close();

                 
				

				//to verify sign
				if(i == nomPage)
				{
					try {
						CertificateFactory cf = CertificateFactory.getInstance("X509");
						Collection col = cf.generateCertificates(new FileInputStream("export.cer"));
						KeyStore kall = KeyStore.getInstance(KeyStore.getDefaultType());
						kall.load(null, null);
						for (Iterator it = col.iterator(); it.hasNext();) {
						    X509Certificate cert = (X509Certificate)it.next();
						    kall.setCertificateEntry(cert.getSerialNumber().toString(Character.MAX_RADIX), cert);
						}
						//KeyStore kall = PdfPKCS7.loadCacertsKeyStore();
						PdfReader reader2 = new PdfReader("signed"+i+".pdf");
						AcroFields af = reader2.getAcroFields();
						ArrayList names = af.getSignatureNames();
						for (int k = 0; k < names.size(); ++k) 
						{
							String name = (String)names.get(k);
							System.out.println("Signature name: " + name);
							System.out.println("Signature covers whole document: " + af.signatureCoversWholeDocument(name));
							System.out.println("Document revision: " + af.getRevision(name) + " of " + af.getTotalRevisions());
							
							PdfPKCS7 pk = af.verifySignature(name);
							Calendar cal = pk.getSignDate();
							java.security.cert.Certificate pkc[] = pk.getCertificates();
							System.out.println("Subject: " + PdfPKCS7.getSubjectFields(pk.getSigningCertificate()));
							System.out.println("Document modified: " + !pk.verify());
							Object fails[] = PdfPKCS7.verifyCertificates(pkc, kall, null, cal);
							if (fails == null)
								System.out.println("Certificates verified against the KeyStore");
							else
								System.out.println("Certificate failed: " + fails[1]);
							
						}
						PdfEncryptor.encrypt(reader,new FileOutputStream("encrypted.pdf"),"Hello".getBytes(),"World".getBytes(),
						PdfWriter.AllowPrinting | PdfWriter.AllowCopy,false);
					}
					catch(Exception e) {e.printStackTrace();}
				}

			}
	//PdfEncryptor.encrypt(reader,new FileOutputStream("encrypted.pdf"),"Hello".getBytes(),"World".getBytes(),
		PdfWriter.AllowPrinting | PdfWriter.AllowCopy,false);

}
catch(Exception e) {e.printStackTrace();}
}
}

-->PdfEncryptor.encrypt(reader,new FileOutputStream("encrypted.pdf"),"Hello".getBytes(),"World".getBytes(),PdfWriter.AllowPrinting | PdfWriter.AllowCopy,false);