My research encompasses security & privacy, systems, networking and HCI (Human Computer Interaction). I truly believe in pushing low-level technical innovation all the way to end users through efficient system integration, usable interface, and meaningful user control. My current research focus is to develop new technical mechanisms to improve consumer privacy through information flow analysis and user interface design. Over the past few years I led the development of many research prototypes including Privacy Scope (a system for finding applications' privacy leaks), Wi-Fi Privacy Ticker (a tool for improving awareness & control of personal information exposure), and TaintDroid (an information flow tracking infrastructure on Android). I have also designed and run user studies to understand people's mental models on various privacy risks in collaboration with HCI experts. I am also currently engaged in developing system architecture for trusted sensing on mobile devices. In the past, I published many papers on network data analysis with emphasis on Internet security.