Professor Amir Houmansadr is a coauthor of “How the Great Firewall of China Detects and Blocks Fully Encrypted Traffic,” named runner-up for the 2025 Caspar Bowden PET Award at the Privacy Enhancing Technologies Symposium. The USENIX Security 2023 paper, written with collaborators at GFW Report, the University of Colorado Boulder, and the University of Maryland, shows how China’s Great Firewall passively detects fully encrypted circumvention traffic, including Shadowsocks, VMess, and Obfs4, and then blocks it. PET Award winners