code: def create_binary_security_token(key_file):
      
      node = etree.Element(
          ns_id('BinarySecurityToken', ns.wssens),
          nsmap={ns.wssens[0]: ns.wssens[1]})
      node.set(ns_id('Id', ns.wsuns), get_unique_id())
      node.set('EncodingType', ns.wssns[1] + 'Base64Binary')
      node.set('ValueType', BINARY_TOKEN_TYPE)
  
      with open(key_file) as fh:
          cert = crypto.load_certificate(crypto.FILETYPE_PEM, fh.read())
          node.text = base64.b64encode(
              crypto.dump_certificate(crypto.FILETYPE_ASN1, cert))
      return node
docs: Create the BinarySecurityToken node containing the x509 certificate.