  Mixed reality (MR) technology development is now gaining momentum due to
advances in computer vision, sensor fusion, and realistic display technologies.
With most of the research and development focused on delivering the promise of
MR, there is only barely a few working on the privacy and security implications
of this technology. This survey paper aims to put in to light these risks, and
to look into the latest security and privacy work on MR. Specifically, we list
and review the different protection approaches that have been proposed to
ensure user and data security and privacy in MR. We extend the scope to include
work on related technologies such as augmented reality (AR), virtual reality
(VR), and human-computer interaction (HCI) as crucial components, if not the
origins, of MR, as well as numerous related work from the larger area of mobile
devices, wearables, and Internet-of-Things (IoT). We highlight the lack of
investigation, implementation, and evaluation of data protection approaches in
MR. Further challenges and directions on MR security and privacy are also
discussed.
