"A nuts-and-bolts explainer book that explores what cryptography does, how it keeps us secure in cyberspace, and why it is so controversial. Though we may not see it, cryptography plays a critical role in our everyday lives, from the movies we stream and our Google searches to even opening our car doors with electronic key fobs. Broadly defined as a set of tools for establishing the basic elements of security in cyberspace, cryptography enables us...