Here is your in-depth guide to cryptography and cryptanalysis in Java. This book includes challenging cryptographic solutions that are implemented in Java 21 and Jakarta EE 11. It provides a robust introduction to Java 21's new features and updates, a roadmap for Jakarta EE 11 security mechanisms, a unique presentation of the "hot points" (advantages and disadvantages) from the Java Cryptography Architecture (JCA), a new chapter on Quantum cryptography, and more. The book dives into the classical simple cryptosystems that form the basis of modern cryptography, with fully working solutions (encryptiondecryption operations). Pseudo-random generators are discussed as well as real-life implementations. Hash functions are covered along with practical cryptanalysis methods and attacks, asymmetric and symmetric encryption systems, signature and identification schemes. The book wraps up with a presentation of lattice-based cryptography and the NTRU framework library. Modern encryption schemes for cloud and big data environments (homomorphic encryption and searchable encryption) also are included. After reading and using this book, you will be proficient with crypto algorithms and know how to apply them to problems you may encounter. Applied cryptography and theoretical cryptography are essential components of the greater science of cryptography, each playing unique but interrelated functions. Comprehending the distinctions between them helps provide an understanding of how cryptographic systems are created, examined, and put into practice. Theoretical cryptography is a branch of cryptography that focuses on the fundamental principles, mathematical theories, and abstract models underlying cryptographic algorithms and protocols. Applied cryptography is a field that deals with the practical implementation and utilization of cryptographic methods in real-world scenarios.