A comprehensive introduction to the fundamentals of provable security for advanced undergraduates. This accessible textbook provides a comprehensive introduction to the algorithms that keep our digital lives safe—how they work, what makes them different, and why they are secure. Mike Rosulek focuses on provable security—the process of defining what it means to be secure and mathematically proving security properties—to demystify the study of cryptography. Writing with clarity and humor, Rosulek covers basic building blocks before moving to symmetric-key encryption and authentication, public-key cryptography, and advanced topics. Employing a novel pseudocode-based approach to learning provable security and security proofs, The Joy of Cryptography empowers anyone with a small amount of programming experience to reason formally about security properties. Uses pseudocode-based reasoning to make provable security accessible to undergraduates Focuses on proven methods used in practice today Offers rigorous treatment of symmetric-key and public-key encryption and authentication Includes advanced material on encrypted messaging, post-quantum cryptography, and zero-knowledge proofs Features ancillary resources