摘要:
整体结构是分组密码的重要特征,也是首要的研究对象,对于分组密码的轮数选取、软硬件实现性能都有非常大的影响.对于类AES算法的设计,当选用非最优分支数的矩阵作为列混淆操作时,向量置换(即字换位操作)的选择可有效提高整体结构的安全性.uBlock类结构是一种类AES结构,通过研究uBlock类结构的特点及其扩散性,给出了其全扩散轮数的下界及等价类划分准则,提出了一种uBlock类结构最优向量置换的搜索策略.依据全扩散轮数最优、超级扩散层的分支数最优及uBlock类结构扩散层的特殊性质,证明了左右向量置换都不能是恒等变换,给出了uBlock类结构的一系列最优向量置换.该搜索策略大幅度减少了需要测试的置换对,为后续uBlock类算法的设计提供技术支持.
Abstract:
The overall structure is an important feature of block cipher and also the primary research object. It has a great influence on the performance of hardware and software in the selection of rounds of block cipher. In the design process of the AES-like ciphers, when using a matrix with a non-optimal branch number for the MixColumns operation, the choice of the vector permutation, i.e., an alternative for ShiftRows, can actually improve the security of the primitive. uBlock-like structure is an AES-like structure. In this paper, we investigate the characteristics and diffusivity of uBlock-like structures, the lower bound of the number of full diffusion rounds and the equivalence class division criteria, and then we propose a search strategy for optimal vector permutations of uBlock-like structures. According to the optimal number of full diffusion rounds, the optimal branch number of the super diffusion layer, and the special properties of the diffusion layer of uBlock-like structure, we prove that the left and right vector permutations cannot be the identity transformation, and a series of optimal vector permutations of uBlock-like structures are given. The search strategy greatly reduces the number of permutation pairs that need to be tested and provides technical support for the design of uBlock-like algorithms.
百度学术
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