code: def get_sp_cert(self):
          
          cert = self.__sp.get('x509cert')
          cert_file_name = self.__paths['cert'] + 'sp.crt'
  
          if not cert and exists(cert_file_name):
              with open(cert_file_name) as f:
                  cert = f.read()
  
          return cert or None
docs: Returns the x509 public cert of the SP.
          :returns: SP public cert
          :rtype: string or None