In addition to laying the foundation for today's online security industry, PKC made encryption technologies accessible to individuals and companies. In view of the many achievements of PKC, it should be accessible to most people. Yet, it is difficult to get a unified account of the evolution of PKC from the scattered literature. It is precisely this gap that this book fills. It covers all the important research directions behind PKC that have been proposed to date, including provable security, implementation, and the state-of-the-art applications such as attribute-based cryptography.