The main objective of this thesis is to make the traditional SHA-256 algorithm computationally efficient and secure. By improving the iterative structure of the SHA-256 algorithm, we change the output of the algorithm from eight 32-bit groupings to four 64-bit groupings, so that the 16 iterations per round of the main loop of the algorithm become eight iterations, thus reducing a total of 32 iterations in four rounds, which in turn improves the computational efficiency of the algorithm, and further improves the avalanche property of the LHF by constructing a logistic chaos The avalanche property of the LHF is further improved by constructing logistic chaos mappings with variable parameters during the message computation. Finally, it is proved through experiments that the probability of bad points in LHF is reduced by 1% compared with MD5, and the probability of bad points in LHF is reduced by 0.3% compared with SHA-256, so it has excellent avalanche and diffusion effect, and also in the performance analysis, the computation efficiency of LHF is accelerated by 53.13% compared with SHA-256 and 14.77% compared with MD5, so it achieves the purpose of speeding up the computational efficiency.
With the wide application of Block chain, the phenomenon of malicious attack of Block chain also increases, which makes Block chain face the risk of data damage, tampering, leakage and so on. And with the increase of data and application, the efficiency of Block chain also needs to be improved. Aiming at the relatively low computational efficiency of the hash function in the block chain, which affects the overall computational efficiency of the block chain and even leads to the security hidden trouble in the block chain, a safe and efficient hash algorithm is proposed. The experimental results show that on the premise of ensuring the security of the algorithm, the efficiency of the hash algorithm is improved, so as to improve the performance of the block chain system.
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