LBlock结构的扩散层研究

计算机工程与应用 ›› 2016, Vol. 52 ›› Issue (1): 100-104.

LBlock结构的扩散层研究

明亚运，祝世雄，曹云飞

保密通信重点实验室，成都 610041

出版日期:2016-01-01 发布日期:2015-12-30

Diffusion layer of LBlock structure

MING Yayun, ZHU Shixiong, CAO Yunfei

Science and Technology on Communication Security Laboratory, Chengdu 610041, China

Online:2016-01-01 Published:2015-12-30

摘要/Abstract

摘要： 最优扩散是分组密码扩散层优良的一个重要指标，Suzaki等人对GFS（广义Feistel结构）做了最优扩散的讨论，但对LBlock型结构的扩散层的最优扩散置换未见文献讨论。借助符号计算软件Mathematica 7.0，将LBlock的分块扩散路径用多项式表达出来，形式化分析此算法[P]层的扩散性。通过穷举所有可能的8元置换，证明了LBlock结构在8轮之前不能达到全扩散；不含移位操作的LBlock结构不能达到全扩散。并且验证了LBlock算法原有的置换[p[8]={2,0,3,1,6,4,7,5}]为最优扩散置换，最后得到了其他一些同样性质优良的置换。

关键词: LBlock结构, 最优扩散, Mathematica 7.0, 符号计算

Abstract: Optimum shuffle is an important index of good diffusion layer of block ciphers. Suzaki et al. have studied optimum shuffles of GFS（Generalized Feistel Structure）, while there is no such research for diffusion layer of LBlock structure. By using the symbolic computation software Mathematica 7.0, this paper obtains the algebraic expressions of LBlock diffusion paths for every round, so that it can analyze the diffusion property of [P] layer of LBlock formally. As it tests all the eight-element permutations involved, the paper proves that LBlock structure cannot achieve all diffusion until 8 rounds; LBlock structure without shift operation cannot achieve all diffusion. It also testifies that the original permutation [p[8]={2,0,3,1,6,4,7,5}] in LBlock is an optimum block shuffle, and some other new optimum shuffles with good properties are presented.

Key words: LBlock structure, optimum shuffle, Mathematica 7.0, symbolic computation

明亚运，祝世雄，曹云飞. LBlock结构的扩散层研究[J]. 计算机工程与应用, 2016, 52(1): 100-104.

MING Yayun, ZHU Shixiong, CAO Yunfei. Diffusion layer of LBlock structure[J]. Computer Engineering and Applications, 2016, 52(1): 100-104.

[1]	彭昌勇1，2，祝跃飞1，黄晓英2，康绯1，滕吉红2. LBlock中间状态的代数表示及其侧信道攻击[J]. 计算机工程与应用, 2012, 48(16): 1-4.
[2]	柳婵娟^1，2，钱旭¹，邹海林². 一种新的PM模型最优扩散参数估计方法[J]. 计算机工程与应用, 2011, 47(6): 20-22.