  While the embedded security research community aims to protect systems by
reducing analog sensor side channels, our work argues that sensor side channels
can be beneficial to defenders. This work introduces the general problem of
synthesizing virtual sensors from existing circuits to authenticate physical
sensors' measurands. We investigate how to apply this approach and present a
preliminary analytical framework and definitions for sensor side channels. To
illustrate the general concept, we provide a proof-of-concept case study to
synthesize a virtual inertial measurement unit from a camera motion side
channel. Our work also provides an example of applying this technique to
protect facial recognition against silicon mask spoofing attacks. Finally, we
discuss downstream problems of how to ensure that side channels benefit the
defender, but not the adversary, during authentication.
