分组密码是密码学的重要分支，在信息安全领域应用广泛。分组密码通常由轮函数和密钥编排方案构成。目前，轮函数的设计已相对成熟，但密钥编排的研究仍不完善：一方面，学界就如何设计与轮函数匹配的安全高效的密钥编排方案还没有一致明确的结论；另一方面，迄今的研究和实践提示我们，无密钥编排的分组算法似乎也是可行的。本项目旨在从密钥编排方案和轮函数的相关性角度研究分组密码的设计。首先，结合前期工作，从密钥有效扩散和统计属性两个方面进一步明确密钥编排方案和轮函数的相关性，并开发自动化检测工具；在上述研究的基础上，分析密钥去编排化的可行性和合理性，考察在不使用密钥编排方案的条件下，如何设计轮函数以使密码算法满足所需要的安全属性，期望给出具有实际指导性的设计准则，并设计新的分组密码；同时，对现有分组密码（如IDEA，AES等），探讨在给定轮函数的条件下如何有针对性、有科学根据地设计最优的密钥编排方案。

Block ciphers play fundamental roles for cryptography in information security, which usually consist of round functions and key schedules. While the design of round functions is maturing, the research on key schedules is widely open: On one hand, how to design secure and efficient key schedules that match with the round function remains unclear; On the other hand, common practice and researches to date indicate that designing block cipher without the key schedule seems to be reasonable. This project will investigate the design of block ciphers in terms of the relationship between key schedules and round functions. First, combined with our previous work, we study such relations from the aspect of effective key diffusion and statistical properties of cipher function, and develop automatic testing tools. Based on this, we analyze the feasibility and rationality of zero key schedule, and study how to design the cryptographic algorithm without using key scheduling to achieve the required security goal. We expect to provide practical guidelines for cipher design as well as design a new block cipher. For some existing block ciphers (such as IDEA, AES, etc.), we explore the customized design of an optimal key schedule for a given round function, so that to provide scientific foundation for the design of block cipher.