关键词: 碰撞分析, SM4算法, 非平衡Feistel结构, 模板匹配

Abstract:

It is found that in the SM4 algorithm of unbalanced Feistel network, the intermediate data from previous and subsequent rounds are relevant. Therefore, the round keys of the SM4 algorithm can be restored through the internal collision principle and the template matching method. And a side channel method of power template-collision analysis based on SM4 algorithm is given. A special set of plaintext is selected to collect the power consumption traces to analyze. And during the algorithm encryption process, the intermediate data (such as the output value of the S-box) in the right half of the unbalanced Feistel network is used as the analysis target. The round keys can be restored by using each round of the S-box output values collision. Experiments prove that approximately 2,500 power consumption traces without masking (except the template traces) are used, which can effectively implement analysis. Compared with the traditional collision analysis, the analysis reduces computational complexity, and extends collision analysis to the unbalanced Feistel network, which improves and enhances the applicability and practicability of collision analysis.

Key words: collision analysis, SM4 algorithm, unbalanced Feistel network, template matching