Study Of Masking Countermeasures Of Symmetric Cryptography

The symmetric cryptographic algorithm plays an important role in security protection in the field of data encryption and transmission.The study on the security of the implementation of the symmetric cryptographic algorithm has drawn much attention from theoretical research and engineering applications.The emergence of side channel attack has put forward higher protection requirements for the security of encryption products.Once information leakage occurs,it will seriously threaten the large-scale application of encryption products.This thesis focuses on the DES algorithm and AES algorithm,and researches the corresponding mask protection technology for anticorrelation power analysis,and proposes a three-level mask protection scheme and a composite field masking scheme.The main research contents and results are as follows:1.We first study the principles of the classic symmetric cryptographic algorithms DES and AES.Based on the theory of power analysis,it analyzes and summarizes the leakage of the DES and AES algorithms.It is found that there is a leakage of Hamming distance between the unprotected DES algorithm and AES algorithm,and the conventation masking scheme of DES has the leakage of Hamming distance of the calculation results of two adjacent rounds,and there is zero leakage of the composite field masking scheme of AES.2.Secondly,We design a three-level masking scheme for DES.By introducing three-level mask registers,the masks are passed between the registers in a pipelined manner,which solves the Hamming distance leakage of the conventation masking scheme.After theoretical analysis of its security,100,000 power consumption curves were collected for CPA attacks in a real environment.The maximum correlation coefficient of the three-level masking scheme is only 0.01,and the conventation Boolean masking scheme is 0.24.The results show that our scheme does not occur the first round of Hamming distance leakage under the 100,000 power consumption curve,and solves the Hamming distance leakage.3.Finally,we design a composite field masking scheme for AES.By designing a zero-resistance circuit,the value entering the mask S-box is always non-zero.In addition,the masking S-box was improved,and a composite field masking scheme was designed to solve the problem of zero leakage of the conventation masking scheme.After theoretically verifying its security,experiments were performed with a power analysis platform.Experimental results show that the maximum correlation coefficient of the Hamming distance model under the 3 million curves of ours is only 0.05.A zero-value attack is performed on the conventation scheme and ours.The maximum correlation coefficient of the conventation one reaches 0.22,while ours has only 0.02.The experimental results show that the AES protection scheme designed in this paper has no leakage of the Hamming distance in the last round under the 3 million power consumption curve,and solves the zero-value leakage problem.The masking schemes designed are verified by FPGA and can be used to guide the security design of actual cryptographic chip products.At the same time,the proposed protection idea can be applied to other different types of symmetric cryptographic algorithms.