在移动互联网、物联网和云计算的高速发展背景下，设计安全高效的轻量级分组密码算法是国家网络安全发展的战略需求。作为分组密码算法最主要的结构之一，ARX因其良好的实现效率在轻量级算法设计中具备独特优势。设计ARX分组密码算法对轻量级密码算法的理论和应用研究具有重要意义。与此同时，随着自动搜索技术成为密码分析的研究热点，ARX算法自动搜索工具的发展和密码分析方法的创新也是亟待解决的重要问题。.本项目在申请人已有工作基础上，围绕ARX算法的设计和自动化分析方法开展研究，具体研究内容包括: (1)基于模加运算构造具有良好密码学性质的T函数，并以此为基础设计新型ARX分组密码算法；(2)优化ARX结构自动搜索方法的数学模型和搜索效率；(3)发展和完善循环异或分析理论，推广循环异或分析的思想和方法。研究成果将为ARX结构分组密码算法的设计与分析提供理论支持和技术贡献。

In the light of mobile internet, IoT and cloud computing, the design of secure and efficient symmetric-key primitives has become a strategic requirement in the development of national network security. As a major structure of the block ciphers, ARX has a unique advantage in the design of lightweight ciphers, due to its efficiency in implementations. Designing ARX block ciphers has a significant importance in the theoretical foundation and application of the lightweight primitives. Meanwhile, as the automatic search techniques becoming a research focus in cryptanalysis, the urgent problems to be solved lie in the development of automatic search tools in ARX and the innovation of the cryptanalytic techniques. .Based on the research basis of the applicant, we will study the design and automated cryptanalysis of ARX block ciphers in the following aspects. (1) Construct modular-addtion-based T-functions with good cryptographic properties, based of which, we design a new ARX block cipher. (2) Optimise the mathematical model and efficiency of the automatic search techniques. (3) Improve the theoretical basis and generalise the idea and methdology of rotational-XOR cryptanalysis. The outputs of this research project will contribute to the theoretical study and technical development of the design and cryptanalysis on ARX block ciphers.