Construction and Analysis of SHA-256 Compression Function Based on Chaos S-Box

Juan Wang,Yongqi Chen,Ge Liu,Shu Wang

doi:10.1109/access.2021.3071501

Abstract

To further improve the security of SHA-256, a compression function construction scheme based on chaotic S-box is proposed. Through the reasonable design of the iteration mode and using the nonlinearity, confusion, and anti-difference of chaotic S-box, the relationship between the plaintext and the hash value becomes more complicated and unpredictable, by the diffusion of the linear transformation P-box, the dependence between the plaintext and the hash value is further improved. The compression function is applied to the SHA-256 Hash Algorithm to test and analyze the distribution, sensitivity, confusion, diffusion, and collision resistance, and compared with the original SHA-256 and the mainstream Hash Algorithms. The results show that the proposed scheme can effectively improve the collision resistance of the SHA-256 Hash Algorithm and enhance the stability of confusion and diffusion with fewer cryptographic components and lower operational consumption to provide more reliable security guarantee for its application.

Highlights

Secure Hash Algorithm 2 (SHA-2) is a Hash Algorithm designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST), including a total of six standard algorithms: SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256 [1]
Compared with the original SHA-256 compression function, three secure and efficient chaotic S-boxes are used to replace the nonlinear function to confuse the outputs of three registers B, C, D, and through the reasonable design of the operation mode, three linear transformation P-boxes are used to diffuse the outputs of the eight registers, realizing the effective enhancement of cryptographic performance
It can be intuitively seen that approximately half of the values change at the corresponding positions of the hash values, which indicate that the compression function constructed based on chaotic S-box will make the SHA-256 Hash Algorithm has strong message sensitivity, to better meet the performance requirement of unidirectional

Summary

INTRODUCTION

With the deepening of S-box research and the development of chaos theory, the S-box with excellent performance based on nonlinearity, randomness, initial value sensitivity, and unpredictability of chaos [18], which provides a new idea for constructing the compression function of SHA-256 Hash Algorithm. Based on the above analysis, this paper proposes to introduce nonlinear chaotic S-box and linear transformation P-box into the compression function of SHA-256 to realize the confusion and diffusion of information respectively, and through the reasonable design of iteration mode, it can achieve effective enhancement of cryptographic performance with fewer cryptographic components and lower operational consumption. Theoretical analysis and experimental results show that the application of the compression function based on the chaotic S-box to the SHA-256 Hash Algorithm can effectively balance the security strength and operation efficiency.

CHAOTIC S-BOX

EXPERIMENTAL ANALYSIS

ANALYSIS OF COLLISION RESISTANCE

CONCLUSION