Verifies the digital signature (XMLDSig) of an XML element.
element is expected to be a node-set with the signed element as its first node, containing the
Signature element in the
http://www.w3.org/2000/09/xmldsig# namespace, or a signed DOM document or an XML string. Only the first node of a provided node-set will be verified.
true() if the included XML
Signature element is valid for the given element,