'Securely create a new encryption key.
Create a new key that is readable by the Keystone group and Keystone
user.
To avoid disk write failure, this function will create a tmp key file
first, and then rename it as the valid new key.'

def _create_new_key(self, keystone_user_id, keystone_group_id):

    self._create_tmp_new_key(keystone_user_id, keystone_group_id)
    self._become_valid_new_key()
