JAVA SOAP: roblem with signing SOAP message

Question

I've a problem with signing SOAP messages with certificate. There is also on top of that HTTP Base Authentication, bu I've only a problem with certs. Let's say I've a single file

cert.pxf

and pasword to this file

passPhrase123

I have code like this:

public class ClientTest {
    public static void main(String[] args) {
        SomeService ss = new SomeService();
        SSPortType ssPortType = ss.getSSPortType();

        BindingProvider provider = (BindingProvider) ssPortType;
        provider.getRequestContext().put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY, "https://193.105.143.152:8001/ws/zus.channel.gabinetoweV2:zla");
        provider.getRequestContext().put(BindingProvider.USERNAME_PROPERTY, "ezla_ag");
        provider.getRequestContext().put(BindingProvider.PASSWORD_PROPERTY, "ezla_ag");

        Binding binding = provider.getBinding();
        List<Handler> handlerList = binding.getHandlerChain();
        handlerList.add(new CertHandler());
        binding.setHandlerChain(handlerList);

        String str =  ssPortType.rpcCall();

        System.out.println(str);
    }
}

And LogicalHandler for dealing with signing SOAP message:

public class CertHandler implements LogicalHandler<LogicalMessageContext> {
    public Set<QName> getHeaders() {
        return Collections.EMPTY_SET;
    }

    public boolean handleMessage(LogicalMessageContext context) {
        Boolean isOutbound = (Boolean) context.get(MessageContext.MESSAGE_OUTBOUND_PROPERTY);
        if (isOutbound.booleanValue()) {
            System.out.println("I've got an outbound message");
            LogicalMessage msg = context.getMessage();
            Source src = msg.getPayload();
            try {
                Node root = null;
                Document doc = null;
                System.out.println("Try to get body");
                if (src instanceof DOMSource) {
                    System.out.println("Hello DOM src");
                    root = ((DOMSource)src).getNode();
                }
                else if (src instanceof SAXSource) {
                    System.out.println("Hello SAX src");
                    SAXSource saxSource = (SAXSource) src;
                    InputSource inSource = saxSource.getInputSource();
                    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                    dbf.setNamespaceAware(true);
                    DocumentBuilder db = dbf.newDocumentBuilder();
                    doc = db.parse(inSource);
                    root = (Node) doc.getDocumentElement();
                }

                //Deal with signing a root
            }
            catch (SAXException se) {
                System.out.println("se: " + se.getMessage());
            }
            catch (ParserConfigurationException pce) {
                System.out.println("pce: " + pce.getMessage());
            }
            catch (IOException ioe) {
                System.out.println("ioe: " + ioe.getMessage());
            }
            catch (IllegalArgumentException iae) {
                System.out.println("iae: " + iae.getMessage());
                System.out.println(iae.getLocalizedMessage());
            }
        }
        else {
            System.out.println("I've got an incoming message");
        }

        return false;
    }

    public boolean handleFault(LogicalMessageContext context) {
        return true;
    }

    public void close(MessageContext context) {
    }
}

Unfortunately I receive always and always again:

I've got an outbound message
Try to get body
Hello SAX src
ioe: null

I got totally stuck... Please help. :)

Could you paste me a small code snippet with solution or point me where I'll get help? Thanks in advance!