Recent developments in sensing and communication technologies have led to an explosion
in the use of mobile devices such as smart phones and tablets. With the increase in the use …

Continuous authentication modalities collect and utilize users' sensitive data to authenticate
them continuously. Such data contain information about user activities, behaviors, and other …

We design privacy-preserving protocols for scaled Manhattan and scaled Euclidean
verifiers, secure against malicious clients and honest-but-curious server. We then augment …

Patterns in the use of mobile devices have the potential to be used as a behavioral biometric
for identification of the device user. We explore the distinctiveness and permanence of …

In an ideal gadget-free environment the user is interacting with the environment and the
services through only “natural” means. This imposes restrictions on many aspects of the …

Continuous authentication enhances security by re-verifying a user's validity during the
active session. It utilizes data about users' behavioral actions and contextual information to …

As many vulnerabilities of one-time authentication systems have already been uncovered,
there is a growing need and trend to adopt continuous authentication systems. Biometrics …

In an implicit authentication system, a user profile is used as an additional factor to
strengthen the authentication of mobile users. The profile consists of features that are …

Risk-based authentication (RBA) extends authentication mechanisms to make them more
robust against account takeover attacks, such as those using stolen passwords. RBA is …

Implicit authentication consists of a server authenticating a user based on the user's usage
profile, instead of/in addition to relying on something the user explicitly knows (passwords …