关键词: 模板攻击, 侧信道攻击, 特征选择, 汉明重量模型, 相关系数, 欧氏距离, SM4分组密码

Abstract: For the electromagnetic radiation leakage during the working of the cryptographic chip, we propose a feature selection method based on the Hamming weight model, which uses the fact that the electromagnetic radiation energy depends on the Hamming weight of the processed data. First, we construct different classifications for the different Hamming weights of the intermediate values of the encryption algorithm. Each classification uses its own selected plaintext to perform repeated encryption operations, and collects the electromagnetic signals radiated by the chip. Then, we calculate the mean value of the electromagnetic signal in each classification and the difference of the mean value of the electromagnetic signal between any two classifications to obtain a difference matrix. Finally, we define a set of variables to constrain the difference matrix, and the points that meet the constraints will be used as feature points. The experiment results show that the Hamming weight model not only can correctly select feature points, but also can significantly reduce the number of electromagnetic leakage traces required for template construction compared with the correlation coefficient feature selection method.

Key words: template attack, side channel attack, feature selection, Hamming weight model, correlation coefficient, euclidean distance, SM4 block cipher