  This paper presents TouchAuth, a new touch-to-access device authentication
approach using induced body electric potentials (iBEPs) caused by the indoor
ambient electric field that is mainly emitted from the building's electrical
cabling. The design of TouchAuth is based on the electrostatics of iBEP
generation and a resulting property, i.e., the iBEPs at two close locations on
the same human body are similar, whereas those from different human bodies are
distinct. Extensive experiments verify the above property and show that
TouchAuth achieves high-profile receiver operating characteristics in
implementing the touch-to-access policy. Our experiments also show that a range
of possible interfering sources including appliances' electromagnetic
emanations and noise injections into the power network do not affect the
performance of TouchAuth. A key advantage of TouchAuth is that the iBEP sensing
requires a simple analog-to-digital converter only, which is widely available
on microcontrollers. Compared with existing approaches including intra-body
communication and physiological sensing, TouchAuth is a low-cost, lightweight,
and convenient approach for authorized users to access the smart objects found
in indoor environments.
