This book discusses the state-of-the-art techniques in the domain of contact tracing applications. Well known in the field of medical science, this topic has received attention from governments, industries and academic communities due to the COVID-19 pandemic. This book provides a link between new proposals related to contact tracing applications and a contextual literature review primarily from the cryptologic viewpoint. As these applications are related to security and privacy of individuals, analyzing them from cryptologic viewpoint is of utmost importance. Therefore, present developments from cryptologic aspects of most proposals around the world, including Singapore, Europe, USA, Australia and India, have been discussed. Providing an in-depth study on the design rationale of each protocol, this book is of value to researchers, students and professionals alike.