Understanding and employing cryptography has become central for securing virtually any digital application, whether user app, cloud service, or even medical implant. Heavily revised and updated, the long-awaited second edition of Understanding Cryptography follows the unique approach of making modern cryptography accessible to a broad audience, requiring only a minimum of prior knowledge. After introducing basic cryptography concepts, this seminal textbook covers nearly all symmetric, asymmetric, and post-quantum cryptographic algorithms currently in use in applications?ranging from cloud computing and smart phones all the way to industrial systems, block chains, and cryptocurrencies. Topics and features: Opens with a foreword by cryptography pioneer and Turing Award winner, Ron Rivest Helps develop a comprehensive understanding of modern applied cryptography Provides a thorough introduction to post-quantum cryptography consisting of the three standardized cipher families Includes for every chapter a comprehensive problem set, extensive examples, and a further-reading discussion Communicates, using a unique pedagogical approach, the essentials about foundations and use in practice, while keeping mathematics to a minimum Supplies up-to-date security parameters for all cryptographic algorithms Incorporates chapter reviews and discussion on such topics as historical and societal context This must-have book is indispensable as a textbook for graduate and advanced undergraduate courses, as well as for self-study by designers and engineers. The authors have more than 20 years? experience teaching cryptography at various universities in the US and Europe. In addition to being renowned scientists, they have extensive experience with applying cryptography in industry, fromwhich they have drawn important lessons for their teaching.