SM4 is a block cipher algorithm among Chinese commer-cial cryptographic algorithms,which is advanced in terms of efficiency and theoretical security and has become national and international stan-dards successively.Howe...SM4 is a block cipher algorithm among Chinese commer-cial cryptographic algorithms,which is advanced in terms of efficiency and theoretical security and has become national and international stan-dards successively.However,existing literature shows that SM4 was not designed with an emphasis on key storage,which means that in today’s world where a single trusted hardware device with the built-in key faces challenges such as vulnerability,high cost,and unreliability,the usabil-ity of SM4 may be limited.Therefore,this paper proposes an imple-mentation scheme for SM4 based on secure multi-party computation(MPC)technology.The scheme involves dispensing the key among mul-tiple users’devices in a distributed manner,and when using the SM4 algorithm for encryption,multiple users perform joint computation with-out opening the full key.Specifically,this paper employs the MP-SPDZ framework,which satisfies security requirements in the presence of a dishonest majority of active adversaries.In view of the fact that this framework can only perform basic linear operations such as addition and multiplication,this paper focuses on the algebraic analysis of Sbox,which is the only non-linear component in SM4,and reconstructs it using the bit decomposition method.Furthermore,this paper demonstrates the conversion between the SM4-Sboxfield GF(28)and the SPDZ parame-terfield GF(240)through the isomorphic mapping,making it possible to perform joint calculations throughout the entire SM4 algorithm.Com-plexity analysis shows that this scheme has advantages in terms of data storage and communication volume,reaching a level of usability.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.61907042Beijing Natural Science Foundation under Grant No.4194090.
文摘SM4 is a block cipher algorithm among Chinese commer-cial cryptographic algorithms,which is advanced in terms of efficiency and theoretical security and has become national and international stan-dards successively.However,existing literature shows that SM4 was not designed with an emphasis on key storage,which means that in today’s world where a single trusted hardware device with the built-in key faces challenges such as vulnerability,high cost,and unreliability,the usabil-ity of SM4 may be limited.Therefore,this paper proposes an imple-mentation scheme for SM4 based on secure multi-party computation(MPC)technology.The scheme involves dispensing the key among mul-tiple users’devices in a distributed manner,and when using the SM4 algorithm for encryption,multiple users perform joint computation with-out opening the full key.Specifically,this paper employs the MP-SPDZ framework,which satisfies security requirements in the presence of a dishonest majority of active adversaries.In view of the fact that this framework can only perform basic linear operations such as addition and multiplication,this paper focuses on the algebraic analysis of Sbox,which is the only non-linear component in SM4,and reconstructs it using the bit decomposition method.Furthermore,this paper demonstrates the conversion between the SM4-Sboxfield GF(28)and the SPDZ parame-terfield GF(240)through the isomorphic mapping,making it possible to perform joint calculations throughout the entire SM4 algorithm.Com-plexity analysis shows that this scheme has advantages in terms of data storage and communication volume,reaching a level of usability.
