关键词: 量子计算, 区块链, 哈希函数, 量子, Merkle树

Abstract: Hash functions play an important role as the cornerstone of security in blockchain systems, playing an irreplaceable role in building consensus mechanisms and protecting data integrity. However, with the accelerated development of quantum technology, the emergence of quantum computers will pose a serious security threat to classical hash functions. Based on the parallel characteristics of quantum computing, Grover’s algorithm can provide squared acceleration compared with the classical counterpart in searching for hash conflicts. Quantum algorithms represented by the Grover’s algorithm can effectively implement quantum computing attacks against classical hash functions, such as mining attacks and forgery attacks. This paper explains the original image collision resistance, weak collision resistance and strong collision resistance of hash functions, and analyzes the main forms of quantum computing attacks against classical hash functions: preimage collision attacks and second image collision attacks. This paper conducts a comparative study on hash functions in blockchain from the perspective of antiquantum security, and five typical hash functions are analyzed and compared from the aspects of construction, input, output, advantages and disadvantages, and proposes the advice for designing hash functions in blockchain. Overall, this paper provides useful references for the design of hash functions in blockchain in the postquantum era.

Key words: quantum computing, blockchain, hash function, quantum, Merkle tree