Abstract:

In the white box attack context,the attacker has full access to the cryptographic system.In order to ensure the key security in the white box attack context,the concept of white-box cryptography is proposed.In 2016,BOS et al.proposed the differential computation analysis (DCA) by introducing the idea of side channel analysis into white-box cryptography for the first time,creating a new path of white box cryptography analysis.DCA takes the software execution trace in the running process of the white-box cryptography program as the analytical object,and uses the statistical analysis method to extract the key.Whether to master the design details of the white-box cryptography or not has little impact on the analysis.The white-box SM4 is the cryptographic implementation of the commercial cryptographic standard algorithm SM4 under the white-box security model.In order to evaluate the security of the white-box SM4 efficiently,a side channel analytical method is proposed for white-box SM4 implementation based on the research on the DCA,called Intermediate-values Mean Difference Analysis (IVMDA).IVMDA directly uses the intermediate value in the process of encryption for analysis,and uses linear combination to counteract the confusion of the white-box SM4.With the participation of at least 60 random plaintexts,the first round key can be completely extracted in about 8 minutes.Compared with the existing analytical methods,this method has the characteristics of convenient deployment,suitability for practical application environment and high analytical efficiency.

Key words: white box implementation, SM4, side channel analysis, differential computational analysis