  As users shift from interacting actively with devices with screens to
interacting seamlessly with smart environments, novel models of user
authentication will be needed to maintain the security and privacy of user
data. To understand users' attitudes toward new models of authentication (e.g.,
voice recognition), we surveyed 117 Amazon Turk workers and 43 computer science
students about their authentication preferences, in contexts when others are
present and different usability metrics. Our users placed less trust in natural
authentication modalities (e.g., body gestures) than traditional modalities
(e.g., passwords) due to concerns about accuracy or security. Users were also
not as willing to use natural authentication modalities except in the presence
of people they trust due to risk of exposure and feelings of awkwardness. We
discuss the implications for designing natural multimodal authentication and
explore the design space around users' current mental models for the future of
secure and usable smart technology.
