针对LBlock算法踪迹驱动Cache攻击S盒特性分析

Completeness Analysis on S-Box of Trace Driven Cache Timing Attack against LBlock Algorithm

针对轻量级密码LBlock算法的Cache计时研究,着重分析密码算法中S盒的非线性结构特征。基于其结构特征推导出S盒的真值表,求解得出S盒输入输出关系的代数表达式;再结合LBlock算法的加密过程和轮函数F的结构,推导出每个轮运算的表达式以及S盒查找索引的代数表达式;结合踪迹驱动Cache计时攻击的攻击原理与模型,总结得出针对LBlock算法Cache攻击中密钥分析的核心表达式,结果表明LBlock算法存在遭受Cache计时攻击的可能性。

Aiming at the study of the cache timing attack for lightweight block cipher called LBlock,we focused on the analysis of the nonlinear structure characteristics of S box in cryptographic algorithms.Firstly,we derived the truth-table of S box based on its structure feature to obtain the relation algebra expression between inputs and outputs of S box. Secondly,with reference of encryption process of the LBlock algorithm and the structure of round function F,the operation expression of each round and the algebra expressions of look-up index for S box were deduced. Finally,we summarized the core expression of the analysis of the key in the cache attack for LBlock algorithm on the basis of the principle and model of the trace-driven cache timing attack. The final conclusion shows that the LBlock algorithm has the possibility of the cache timing attack.