Tangible Security for Mobile Devices

Existing measures to secure the internal data on mobile devices can generally fall into two categories: passwords and biometrics. Neither is satisfactory, for different reasons. We propose a new scheme, analogous to using physical keys to unlock doors or a plug-in security dongle to unlock software. The user wears one or more security tokens whose presence in the close proximity of the user’s cell phone allows the secrets on the phone to be unlocked. As long as the thief is unable to steal both the token and the cell phone, security is mostly guaranteed. We call this approach tangible security. This preliminary paper describes how such a system could be built and used.