密码学涉及解决安全问题的计算系统的概念、定义及构造。密码系统的设计必须基于坚实的基础。本书对这一基础问题给出了系统而严格的论述：用已有工具来定义密码系统的目标并解决新的密码学问题。本书的重点是澄清基本概念并论述解决几个主要密码问题的可行性，而不侧重于对特殊方法的描述。

This book presents the basic paradigms and principles of modern cryptography. It is designed to serve as a textbook for undergraduate- or graduate-level courses in cryptography (in computer science or mathematics departments), as a general introduction suitable for self-study (especially for beginning graduate students), and as a reference for students, researchers, and practitioners.