Immersive technologies, including augmented and virtual reality (AR & VR) devices, have enhanced digital communication along with a considerable increase in digital threats. Thus, authentication becomes critical in AR & VR technology, particularly in shared spaces. In this paper, we propose applying the ZeTA protocol that allows secure authentication even in shared spaces for the AR & VR context. We explain how it can be used with the available interaction methods provided by Head-Mounted Displays. In future work, our research goal is to evaluate different designs of ZeTA (e.g., interaction modes) concerning their usability and users' risk perception regarding their security - while using a cross-cultural approach.