This lecture covers the principles of Privacy by Design, emphasizing proactive and preventative approaches, default privacy settings, and end-to-end security. It explores the concept of data minimization and trust minimization, along with technological solutions. The instructor discusses the SwissCovid app as a privacy-by-design example, detailing its purpose, design, and security mechanisms. The lecture delves into the system design, security mechanisms, and the psychological acceptability of SwissCovid, highlighting its engineering challenges and future directions in presence tracing.