This book equips readers with an access control logic they can use to specify and verify their security designs. Throughout the text, the authors use a single access control logic based on a simple propositional modal logic. The first part of the book presents the syntax and semantics of access control logic, basic access control concepts, and an introduction to confidentiality and integrity policies. The second section covers access control in networks, delegation, protocols, and the use of cryptography. In the third section, the authors focus on hardware and virtual machines. The final part discusses confidentiality, integrity, and role-based access control.