public static void signElementByTag(SOAPMessage soapMessage, String tag) throws Exception{
    	//Инициализиция JCP
        com.sun.org.apache.xml.internal.security.Init.init();
        SpecUtility.initJCP();
        
        //Загрузка хранилища
        KeyStore keyStore = KeyStore.getInstance(JCP.HD_STORE_NAME);
        keyStore.load(null, null);

        //Ключ и сертификат
        PrivateKey privateKey = (PrivateKey)keyStore.getKey(SpecUtility.DEFAULT_ALIAS, SpecUtility.DEFAULT_PASSWORD);
        X509Certificate cert = (X509Certificate) keyStore.getCertificate(SpecUtility.DEFAULT_ALIAS);
                
        //Формируем новый документ из части сообщения
        NodeList tagNodeList = soapMessage.getSOAPPart().getElementsByTagName(tag);
        Document newXMLDocument = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
        Node copyNode = newXMLDocument.importNode(tagNodeList.item(0), true);
        newXMLDocument.appendChild(copyNode);
        
        //Подписываемый элемент
        NodeList newNodeList = newXMLDocument.getElementsByTagName(tag);
        Element signedNode = (Element)newNodeList.item(0);
        
        Provider xmlDSigProvider = new ru.CryptoPro.JCPxml.dsig.internal.dom.XMLDSigRI();

        XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM", xmlDSigProvider);

        List<Transform> transformList = new ArrayList<>();
       
        Transform transform = fac.newTransform(Transform.ENVELOPED, (XMLStructure) null);
        Transform transformC14N = fac.newTransform(Transforms.TRANSFORM_C14N_EXCL_OMIT_COMMENTS, (XMLStructure) null);
        transformList.add(transform);
        transformList.add(transformC14N);
        
        Reference ref = fac.newReference("", fac.newDigestMethod("http://www.w3.org/2001/04/xmldsig-more#gostr3411", null), transformList, null, null);

        SignedInfo si = fac.newSignedInfo(fac.newCanonicalizationMethod(CanonicalizationMethod.EXCLUSIVE,
            (C14NMethodParameterSpec) null),
            fac.newSignatureMethod("http://www.w3.org/2001/04/xmldsig-more#gostr34102001-gostr3411", null),
            Collections.singletonList(ref));

        KeyInfoFactory kif = fac.getKeyInfoFactory();
        X509Data x509d = kif.newX509Data(Collections.singletonList(cert));
        KeyInfo ki = kif.newKeyInfo(Collections.singletonList(x509d));

        javax.xml.crypto.dsig.XMLSignature sig = fac.newXMLSignature(si, ki);

        DOMSignContext signContext = new DOMSignContext(privateKey, signedNode);
        signContext.putNamespacePrefix(javax.xml.crypto.dsig.XMLSignature.XMLNS, "ds");
        sig.sign(signContext);
        
        //Заменяем исходный элемент на подписанный
        Document doc = soapMessage.getSOAPPart().getEnvelope().getOwnerDocument();
        Node signedTag = newXMLDocument.getFirstChild();
        Node oldNode = tagNodeList.item(0);
        Node parentNode = oldNode.getParentNode();
        parentNode.removeChild(oldNode);
        Node newNode = doc.importNode(signedTag, true);
        parentNode.appendChild(newNode);

    }