Issa Khalil

In this paper, we leverage the characteristics of round-trip communications latency (RTL) to design and implement a novel highly secure and usable web authentication scheme, dubbed CLAS. CLAS uses, in addition to the traditional credentials, round-trip network communications latency to uniquely identify users. CLAS introduces a novel network architecture which turns RTL into a robust authentication feature that is extremely difficult to forge. CLAS offers robust defense against password compromise because, unlike many traditional authentication mechanisms, it is resilient to phishing/pharming, man-in-the-middle, and social engineering attacks. Most importantly, CLAS is transparent to users and incurs negligible overhead. Our experimental results show that CLAS can achieve 0.0017 false positive rate while maintaining false negative rate below 0.007.

—Indoor localization is very important to enable Internet-of-things (IoT) applications. Visible light communication (VLC)-based indoor localization approaches embrace many advantages, such as utilization of existing ubiquitous lighting infrastructure, high location and orientation accuracy, and no interruption to RF-based devices. However, existing VLC-based localization methods lack a real-time backward channel from the device to landmarks and necessitate computation at the device, which make them unsuitable for real-time tracking of small IoT devices. In this paper, we propose and prototype a retroreflector-based visible light localization system RETRO, that establishes an almost zero-delay backward channel using a retroreflector to reflect light back to its source. RETRO locates passive IoT devices without requiring computation and heavy sensing (e.g. camera) at the devices. Multiple photodiodes (i.e. landmarks) are mounted on any single unmodified light source to sense the retroreflected optical signal (i.e. location signature). We theoretically derive a closed-form expression for the reflected optical power related to the location and orientation of the retroreflector, and validate the theory by experiments. The characterization of received optical power is applied to a received signal strength indicator (RSSI) and trilateration based localization algorithm. Extensive experiments demonstrate centimeter-level location accuracy and single-digit angular error.