Current touch devices separate user authentication from regular
interaction, for example by displaying modal login
screens before device usage or prompting for in-app passwords,
which interrupts the interaction flow. We propose
biometric touch sensing, a new approach to representing
touch events that enables commodity devices to seamlessly
integrate authentication into interaction: From each touch,
the touchscreen senses the 2D input coordinates and at the
same time obtains biometric features that identify the user.
Our approach makes authentication during interaction transparent
to the user, yet ensures secure interaction at all times.
To implement this on today’s devices, our watch prototype
Bioamp senses the impedance profile of the user’s wrist and
modulates a signal onto the user’s body through skin using a
periodic electric signal. This signal affects the capacitive values
touchscreens measure upon touch, allowing devices to
identify users on each touch. We integrate our approach into
Windows 8 and discuss and demonstrate it in the context of
various use cases, including access permissions and protecting
private screen contents on personal and shared devices