| 摘要: |
| 差分-线性分析是一种组合类分析方法, 已经被应用于许多对称密码的分析中. 特别地, 对于ARX类分组密码算法SPECK, 差分-线性分析是评估其安全性的一种强有力的方式. 在最新的差分-线性分析框架中, 密码算法被分解为3部分: 差分部分、中间部分和线性部分, 其中差分部分、中间部分和线性部分分别包含高概率的差分特征, 高相关性的差分-线性逼近和高相关性的线性逼近, 组合3部分特征可以得到一个完整的差分-线性区分器. 对于ARX类对称密码算法, 在传统的差分-线性区分器的搜索过程中, 通常是首先借助实验方法来计算得到中间部分一个高相关性的差分-线性逼近, 然后再分别向前向后搜索线性特征和差分特征, 但是该策略容易忽视掉一些好的差分-线性区分器. 区别于传统的搜索算法, 该算法结合高相关性的差分-线性逼近中差分部分和线性部分的特点, 从高概率的差分特征和线性特征出发, 给出一个差分-线性区分器搜索算法. 将所提搜索算法应用于SPECK中, 得到SPECK32的11轮差分-线性区分器和SPECK48的12轮差分-线性区分器. 所提区分器都优于SPECK32/48目前已知最好的差分-线性区分器. |
| 关键词: 密码分析 对称密码 差分-线性分析 SPECK 分组密码 |
| DOI：10.13328/j.cnki.jos.007457 |
| 分类号:TP309 |
| 基金项目:国家自然科学基金(62072445) |
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| Improved Differential-linear Analysis on Round-reduced SPECK |
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ZHANG Yu-Han1,2, ZHANG Lei1,2, WU Wen-Ling1,2
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1.Trusted Computing and Information Assurance Laboratory, Institute of Software, Chinese Academy of Sciences, Beijing 100190, China;2.University of Chinese Academy of Sciences, Beijing 100049, China
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| Abstract: |
| Differential-linear cryptanalysis, a combined cryptanalysis method, has been applied to the analysis of many symmetric ciphers. Specifically, for the ARX block cipher SPECK, differential-linear cryptanalysis is an effective technique for evaluating its security. In the latest framework of differential-linear cryptanalysis, the cipher is divided into three components: the differential part, the middle part, and the linear part. These parts contain high-probability differential characteristics, high-correlation differential-linear approximations, and high-correlation linear approximations, respectively. For ARX ciphers, the traditional search process for differential-linear distinguishers typically involves first using experimental methods to obtain a high-correlation differential-linear approximation in the middle part. Subsequently, linear and differential characteristics are searched for forward and backward. However, this strategy may overlook some effective differential-linear distinguishers. This study proposes a search method for differential-linear distinguishers, which integrates the characteristics of the differential and linear parts in high-correlation differential-linear approximations and leverages high-probability differential and linear characteristics. The proposed search algorithm is applied to SPECK, yielding an 11-round differential-linear distinguisher for SPECK32 and a 12-round differential-linear distinguisher for SPECK48. Both outperform the best-known differential-linear distinguishers for these ciphers. |
| Key words: cryptanalysis symmetric cipher differential-linear cryptanalysis SPECK block cipher |
