当今，尤其是“棱镜门”事件之后，信息的安全存储、处理和传输越来越重要，而分组密码是实现数据保密性和完整性的核心机制，其研究内容主要包括分组密码的设计和分析。在分组密码的分析中，中间相遇攻击、不可能差分分析、Biclique分析、Sieve-in-the-middle攻击近来被成功地用来评估一些著名分组密码的安全性，但针对它们的攻击效率与分组密码整体结构、非线性层、扩散层和密钥扩展算法的关系研究相对比较少。本项目将运用这些分析方法给出对轻量级分组密码TWINE、SIMON和SPECK的最好攻击结果，进而在此基础上提炼出分组密码各模块对它们的影响，特别是研究非线性部分对搜索不可能差分链的影响和密钥扩展算法对Biclique分析、Sieve-in-the-middle攻击等影响。我们的结果不仅改进了分组密码的分析方法，也影响着人们对算法的使用信心，为分组密码的设计提供理论依据。

Since the prism program was exposed in 2013, all the countries in the world have paid more attentions to information storage, management and transmission. As an important part within the infrastructure of information and network security, block ciphers are served as the core cryptographic algorithm which can be used to guarantee the data confidentiality and integrity. Up to now, there are two main aspects including design and cryptanalysis of block ciphers. For cryptanalysis of block ciphers, four attacks, i.e., meet-in-the-middle attack, impossible differential cryptanalysis, biclique cryptanalysis and sieve-in-the-middle attack, have been used to analyze the securities of many popular block ciphers successfully. However, only a few researches focused on the relations between these attacks and the structure, the non-linear layer, the linear layer and the key schedule of block ciphers. In this project, we will evaluate the securities of some light-weight block ciphers, such as TWINE, SIMON and SPECK, by means of these four attacks. Our cryptanalytic results will be better than previous ones. Based on them, the relations between the efficiencies of these attacks and every part of a block cipher will be presented, especially the relations between the efficiency of impossible differential cryptanalysis and the non-linear part of a block cipher, the relations between the efficiency of biclique cryptanalysis and the key schedule of a block cipher, and the relations between the efficiency of sieve-in-the-middle attack and the key schedule of a block cipher. Our results will not only push forward the analysis theory of block cipher dramatically, but also result in considerable improvement of the design theory of block ciphers.