Differential Analysis Of Lightweight Block Ciphers Based On MILP

Lightweight cryptography is a branch of symmetric cryptography,which occupies fewer resources,has low power consumption,simple hardware implementation,and high security for network data.The lightweight block cipher structure of the SPN structure is relatively simple,and it is particularly important to analyze its security.This paper mainly uses the MILP automated search technology to conduct a differential analysis of the two lightweight block ciphers of the SPN structure,Skinny and Gift,and gives their security evaluation.This paper first analyzes the structure of the lightweight block cipher algorithm of the SPN structure,including the analysis of the replacement layer,the diffusion layer,and the key plus layer.Based on the analysis of their structure,the transfer law of differential values in the encryption process is obtained.In the part of constructing the MILP model,this paper discusses the methods of constructing the MILP model of the linear part and the non-linear part.In the linear part,the transmission rule of the difference value is relatively simple,and it is usually consistent with the operation relationship of the round function or does not introduce any difference.In the non-linear part,this paper studies the difference distribution table of S-box,the relationship between input difference and output difference,and constructs the MILP model of S-box through impossible difference distribution table.This paper proposes a greedy algorithm that can minimize the MILP model constructed by the nonlinear part as much as possible,so that the model can be solved as fast as possible.Based on the analysis of the structure of the lightweight block cipher algorithm of SPN structure and the law of differential value transfer,this paper selects two block cipher algorithms-Skinny and Gift,and constructs MILP models and solves them.In the process of constructing the model,the constructed model is greatly simplified,and the solution is optimized in time and space as much as possible.Then,this paper uses the LPSolve linear programming solver to solve the constructed MILP,and finds the difference path with the highest probability in the 11 rounds of the two versions of Skinny-64 and Gift-64.The differential propagation probability corresponding to the differential path of Experimental data shows that for11 rounds of differential attacks,Skinny-64's differential spread is much faster than Gift-64,that is,Skinny-64's resistance to differential cryptanalysis is much stronger than Gift-64.The basic reason is that the diffusion layer of the Gift's encryption round function is much simpler than Skinny,making the diffusion layer's influence on differential diffusion very weak.