Implicit User Re-Authentication for Mobile Devices

Portable computers are used to store and access sensitive information. They are frequently used in insecure locations with little or no physical protection, and are therefore susceptible to theft and unauthorized access. The paper proposes an implicit user re-authentication system for portable computers that requires no application changes or hardware modifications. The proposed technique observes user-specific patterns in filesystem activity and network access to build models of normal behavior. These are used to distinguish between normal use and anomalous use. The paper describes these automated model generation and user detection techniques, and explains how to efficiently implement them in a wireless distributed system composed of servers and battery-powered portable devices.