Как получить и добавить теги x509data и x509certificate в xml, созданный с помощью следующего кода

 String providerName = System.getProperty("jsr105Provider",
   "org.jcp.xml.dsig.internal.dom.XMLDSigRI");

 XMLSignatureFactory fac =
   XMLSignatureFactory.getInstance("DOM",
   (Provider) Class.forName(providerName).newInstance());

 Reference ref =
   fac.newReference("",
       fac.newDigestMethod(DigestMethod.SHA1, null),
           Collections.singletonList(
               fac.newTransform(Transform.ENVELOPED,(XMLStructure) null)), 
       null, null);

   SignedInfo si = fac.newSignedInfo
       (fac.newCanonicalizationMethod
         (CanonicalizationMethod.INCLUSIVE_WITH_COMMENTS, 
            (XMLStructure) null), 
        fac.newSignatureMethod(SignatureMethod.RSA_SHA1, 
            null),
        Collections.singletonList(ref));

   KeyPairGenerator kpg = 
       KeyPairGenerator.getInstance("RSA");
   kpg.initialize(512);
   KeyPair kp = kpg.generateKeyPair();

   KeyInfoFactory kif = fac.getKeyInfoFactory();
   KeyValue kv = kif.newKeyValue(kp.getPublic());

   KeyInfo ki = 
       kif.newKeyInfo(Collections.singletonList(kv));

   DocumentBuilderFactory dbf =
       DocumentBuilderFactory.newInstance();
   dbf.setNamespaceAware(true);
   Document doc1 = 
       dbf.newDocumentBuilder().
       parse(new FileInputStream("C:/Documents and Settings/sbtho/Desktop/downloads/samp.xml"));

   DOMSignContext dsc = new DOMSignContext
    (kp.getPrivate(), doc.getDocumentElement());


   XMLSignature signature = fac.newXMLSignature(si, ki);
      signature.sign(dsc);

   TransformerFactory tf = TransformerFactory.newInstance();
   Transformer trans = tf.newTransformer();

   trans.transform(
       new DOMSource(doc),
       new StreamResult(
           new FileOutputStream("C:/Documents and Settings/sbtho/Desktop/downloads/signedsamp.xml")));

вывод приведенного выше кода выглядит следующим образом, и я хочу вставить теги x509 в тег keyinfo.

    
  
    
  
  
    
    
    
    
     
    
     
    Kjgj/nVt41Q8gfDwSdfTGW42FQ8= 
    
    
      nhdbvODcXYvc5w65todyDBkVJJW/VgN3sxMjILO+qavIln0np57qSYvC6CjavLEdD5KZ0uLoD7r/ o07X9k3I5Q== 
 
 
 
   qc/XQnBZ2/waPw+wUmdFiYUEY8RDLpaDn+Xmm56WoHn9jKKB0BCrYxz33q+z4O7VwQdv1eAdv9cK eTHEEpJpIQ== 
  AQAB 
  
  
  
  
  

и как создается сертификат x509?