5. DEALING WITH DEVICE LOSS
With the phone holding increasing amounts of private, as well
as financial data, loss of the device is a top concern. Password
authentication has been the de facto standard for securing
user data, yet passwords do not work well on smartphones:
small or touch-based keyboards and frequent unlock events
make entering a password every time a nuisance. The alternative
is to build a hardware authenticator, in the form of
a ring, wristband, or key, which can unlock the user’s phone
without requiring any interaction. A stolen device will be
impossible to unlock without the matching authenticator.