One of the biggest and most important topics in mobile and ubiquitous computing is privacy and security. Having lots of devices transmitting huge amounts of telemetry all over the world comes with a number of privacy and security challenges. We'll start off by considering a 'local' or on-person threat to privacy in the form of RFID cards. Then we'll cover a little on cloud-based computing and the privacy and security challenges there. We'll finish by thinking about user perspectives on security and how these can be represented in preferences.