A WiFi network usually feels like invisible infrastructure, something that simply moves data from a phone or laptop to the internet. But researchers have shown that the same radio signals already filling homes, offices, cafés and public spaces can reveal far more than whether a device is connected. By studying how WiFi radio waves move through a room, researchers can reconstruct information about people and potentially recognize who is standing there, even when that person carries no connected device. The finding comes from researchers at KASTEL, KIT's Institute of Information Security and Dependability, who demonstrated a system capable of identifying people through ordinary wireless signals. In experiments involving 197 participants, the system reached almost 100 percent identification accuracy. It remained effective when people were viewed from different angles and when they changed the way they walked. The result points to an unusual privacy problem because the technology does not depend on a visible camera or a wearable device.
