A broad introduction to cryptography—what it is, how it really works, what its future holds, and why every informed citizen should understand its basics. We all keep secrets—from our gym locker codes to our email passwords to our online interactions. And we choose to share those secrets only with those whom we trust. So, too, do organizations, businesses, governments, and armies. In this fascinating book Cryptography, Panos Louridas provides a broad and accessible introduction to cryptography, the art and science of keeping and revealing secrets. Louridas explains just how cryptography works to keep our communications confidential, tracing it back all the way to its ancient roots. Then he follows its long and winding path to where we are today and reads the signs that point to where it may go tomorrow. A few years back, interest in cryptography was restricted to specialists. Today, as we all live our lives attuned to our digital footprint and the privacy issues it entails, it becomes more and more essential to have a basic understanding of cryptography and its applications to everyday life. Starting with classical cryptography, Cryptography takes the reader all the way up to the twenty-first century cryptographic applications that underpin our lives in the digital realm. Along the way, Louridas also explains concepts such as symmetric cryptography, asymmetric cryptography, cryptographic protocols and applications, and finally, quantum and post-Quantum cryptography as well as the links between cryptography and computer security.