def authenticate_external(self, auth_params):
        """Verify credentials using the external auth library.

        in auth_params of type str
            The auth parameters, credentials, etc.

        out result of type str
            The authentification result.

        """
        if not isinstance(auth_params, list):
            raise TypeError("auth_params can only be an instance of type list")
        for a in auth_params[:10]:
            if not isinstance(a, basestring):
                raise TypeError(
                        "array can only contain objects of type basestring")
        result = self._call("authenticateExternal",
                     in_p=[auth_params])
        return result