SecurePart securePart = new SecurePart(
new QName("urn:example:po", "PaymentInfo"),
SecurePart.Modifier.Content,
new String[]{"http://www.w3.org/2001/10/xml-exc-c14n#"},
"http://www.w3.org/2000/09/xmldsig#sha1");
properties.addSignaturePart(securePart);
OutboundXMLSec outboundXMLSec = XMLSec.getOutboundXMLSec(properties);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
XMLStreamWriter xmlStreamWriter = outboundXMLSec.processOutMessage(baos, "UTF-8");