Design And Implementation Of SM4 Algorithm Optimization And Key Expansion Algorithm

With the rapid development of Internet of things and interstellar communication,it is very important to complete the safe transmission of data on the hardware platform with limited resources.In order to ensure the security of data communication,China has developed a variety of cryptographic algorithms with independent intellectual property rights since the 21 st century.Among them,SM4 algorithm is a group symmetric encryption algorithm issued by the State Password Administration.It was determined as the standard of group cipher.SM4 algorithm includes encryption and decryption module and key expansion module,both of which are based on 32 round Feistel structure.SM4 algorithm is based on cyclic iterative structure,when processing multiple groups of data,the data processing speed and data throughput are limited.The parameters involved in the XOR operation in the key extension module are obtained by the fixed algorithm,that is,the parameters are fixed,so they are easy to be cracked.To solve the above problems,this paper optimizes the iterative structure of SM4 algorithm,and uses chaos algorithm to optimize the key expansion module.Firstly,the basic iteration structure of SM4 algorithm is optimized by external pipeline.32 round function modules are connected in series by inserting registers,and 32-Level pipeline structure is designed.When the pipeline structure is used to encrypt multiple groups of data,the data throughput and processing speed are significantly improved,which is about 23 times of the basic iterative structure.Secondly,aiming at the problem that the XOR part of the key expansion algorithm uses 32 fixed parameters,which makes SM4 relatively easy to crack,the lightweight chaos algorithm is used to optimize it.The pseudo-random sequence generated by the chaotic algorithm is used as the parameters in the key expansion algorithm,and part of the initial key of SM4 algorithm is used as the initial value of the chaotic algorithm,so that the generation of parameters is closely related to the initial key,which changes with the change of the key,so as to improve the security of the algorithm.The three chaos algorithms are Logistic chaos algorithm,Henon chaos algorithm and Lorenz Chaos Algorithm.The three chaos algorithms are mixed with the key expansion algorithm to realize the data encryption and decryption of the hybrid algorithm.The performance of the hybrid encryption and decryption algorithm are analyzed and compared.It is proved that the chaos algorithm can optimize the SM4 algorithm.By comparing the differences of SM4-Logistic,SM4-Henon and SM4-Lorenz hybrid encryption and decryption,the main encryption module of the hybrid algorithm is determined,and a reconfigurable system is designed to optimize the SM4 algorithm by three chaotic algorithms.The state machine is used to realize the enable selection of three chaotic algorithms,which verifies the correctness of the encryption and decryption function of the reconfigurable system data,improves the security and flexibility,and saves the consumption of logical resources.