test.py

#       Load X.509 data from XML-Security signed XML file with KeyInfo
#
#       import xmlsec,libxml2
        from M2Crypto import X509
        s= xmlsec.findNode(
                    libxml2.parseDoc(self.signed_xml.encode('UTF-8')).getRootElement(),
                    xmlsec.NodeX509Certificate,xmlsec.DSigNs).content
        s = '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----\n' % s 
        cert = X509.load_cert_string(s)
        print type(cert),cert.__class__
#       <type 'instance'> M2Crypto.X509.X509