Feistel-SP结构典型密码的差分特征搜索
发布时间：2019-03-26 13:24
【摘要】：本文主要研究对象为Feistel-SP结构典型分组密码,该系列分组密码有Camellia,MIBS,E2等。论文针对不同的Feistel-SP结构分组密码建立合理的差分传播系统,并搜索出Feistel-SP结构典型分组密码的多轮差分模式和多轮差分路径。论文主要进行了以下研究工作:首先,把Matsui算法思想应用到Feistel-SP结构中,并对其进行优化和改进。通过把S盒差分分布表转变成密集型分布表,建立合理的差分传播模型,进而提出一种基于向量的严格剪枝技术,以便尽早地筛选掉不满足剪枝条件的差分路径。以轻量级分组密码MIBS为例,应用此自动化搜索技术,搜索出4轮最优差分概率是2-12,并给出其R(4≤R≤11)轮的差分特征,同时也搜索出两条12轮最优差分路径,其概率为2-56,这是目前为止最好的结果。其次,提出了一种新的符号差分表示方法,并提出一种新的自动化搜索技术,搜索出Feistel-SP结构典型分组密码的最优迭代差分模式,应用此思想不仅可以大大地降低了计算复杂性,还能通过迭代差分模式构造出多轮的差分特征。论文以轻量级分组密码MIBS为例,给出了MIBS的3轮、4轮最优迭代差分概率,概率分别为2-20、2-26,并搜索出所有满足条件的最优迭代差分路径,由于论文提出的是一种针对Feistel-SP结构的通用性搜索算法,因此论文还以Camellia为例进行了适用性分析。通过建立其差分传播系统,替换F函数中的S盒和P置换组件,搜索出迭代差分模式,进而搜索出高概率迭代差分路径。最终给出Camellia的3,4轮最优迭代差分模式和最优迭代差分特征,其迭代概率分别为2-52,2-71,这个结果是目前为止最优的。最后,通过改进的Matsui自动化搜索算法,我们得到了两条12轮高概率差分路径,使用选择明文攻击方法,分别计算了恢复13和14轮密钥比特成功的概率。总结了密钥恢复的一般思路和步骤,引入信噪比概念,并用计数器统计正确密钥对与错误密钥对,信噪比操作主要进行了采样、去噪和提纯三个方面的工作。表5.1给出的13轮和14轮分析数据,13轮密钥恢复成功概率为99.9%,14轮密钥恢复成功概率为50.15%。
[Abstract]:In this paper, the main research object is Feistel-SP structure typical block cipher, this series of block ciphers have Camellia,MIBS,E2 and so on. In this paper, a reasonable differential propagation system is established for different Feistel-SP block ciphers, and the multi-round differential mode and multi-round differential path of typical Feistel-SP block ciphers are searched. The main work of this paper is as follows: firstly, the idea of Matsui algorithm is applied to the Feistel-SP structure, and its optimization and improvement are carried out. By transforming the S-box difference distribution table into a dense distribution table, a reasonable differential propagation model is established, and then a vector-based strict pruning technique is proposed in order to screen out the difference paths that do not satisfy the pruning condition as soon as possible. Taking lightweight block cipher MIBS as an example, using this automatic search technique, the optimal differential probability of 4 rounds is 2? 12, and the differential characteristics of its R (4 鈮，
本文编号：2447585
[Abstract]:In this paper, the main research object is Feistel-SP structure typical block cipher, this series of block ciphers have Camellia,MIBS,E2 and so on. In this paper, a reasonable differential propagation system is established for different Feistel-SP block ciphers, and the multi-round differential mode and multi-round differential path of typical Feistel-SP block ciphers are searched. The main work of this paper is as follows: firstly, the idea of Matsui algorithm is applied to the Feistel-SP structure, and its optimization and improvement are carried out. By transforming the S-box difference distribution table into a dense distribution table, a reasonable differential propagation model is established, and then a vector-based strict pruning technique is proposed in order to screen out the difference paths that do not satisfy the pruning condition as soon as possible. Taking lightweight block cipher MIBS as an example, using this automatic search technique, the optimal differential probability of 4 rounds is 2? 12, and the differential characteristics of its R (4 鈮，
本文编号：2447585
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