A Privacy Awareness System for Ubiquitous Computing Environments Marc Langheinrich Institute of Information Systems, ETH Zurich 8092 Zurich, Switzerland www.inf.ethz.ch/~langhein Abstract. Protecting personal privacy is going to be a prime concern for the deployment of ubiquitous computing systems in the real world. With daunting Orwellian visions looming, it is easy to conclude that tamper-proof technical protection mechanisms such as strong anonymization and encryption are the only solutions to such privacy threats. However, we argue that such perfect protection for personal information will hardly be achievable, and propose instead to build systems that help others respect our personal privacy, enable us to be aware of our own privacy, and to rely on social and legal norms to protect us from the few wrongdoers.We introduce a privacy awareness system targeted at ubiquitous computing environments that allows data collectors to both announce and implement data usage policies, as well as providing data subjects with technical means to keep track of their personal information as it is stored, used, and eventually removed from the system. Even though such a system cannot guarantee our privacy, we believe that it can create a sense of accountability in a world of invisible services that we will be comfortable living in and interacting with.