Research On The Application Of Verifiable Delay Function In Blockchai

With the arrival of the digital economy era,blockchain technology has brought opportunities for the development of all walks of life.The ensuing blockchain security issues have also become more and more obvious.The blockchain uses the timestamp mechanism to combine blocks in a sequentially connected manner into a chained structure,and generates random numbers through a consensus algorithm to decide to add new blocks.The existing blockchain data has poor reliability,integrity is difficult to verify,and privacy is difficult to guarantee.These problems have led to threats to the security and credibility of the blockchain.The unpredictable and verified characteristics of the verifiable delay function has overturned the existing distributed system and has been widely used in blockchain.The verifiable delay function is a perfect complement to the blockchain.It protects the blockchain from various attacks by introducing unpredictable delays,thereby improving the security,trustworthiness and reliability of the blockchain.This article summarizes the various types of verifiable delay functions,combines different kinds of verifiable delay functions to conduct research in the blockchain,and proposes two innovative schemes:(1)This thesis provides a comprehensive summary of various types of verifiable delay functions in response to the issue of incomplete reviews of candidate structures for verifiable delay functions.Firstly,it gives a description and characteristics of verifiable delay functions,and introduces four basic types of verifiable delay functions,namely,weak verifiable delay functions,incremental verifiable delay functions,decodable verifiable delay functions,and trapdoor verifiable delay functions.Then,it explains that the construction of verifiable delay functions generally relies on two security assumptions: algebraic assumptions or structural assumptions,and cryptographic theories describe two different security assumptions for verifiable delay functions.Finally,a post-quantum verifiable delay function based on hyperelliptic curve cryptography is elaborately introduced.(2)Innovation 1 is aimed at the problem that the timestamp generated in the blockchain may be tampered with or forged,this thesis analyzes the research progress of the timestamp scheme based on blockchain,and proposes a continuous verifiable delay function based blockchain distributed timestamp.The distributed model uses multiple timestamp servers to provide timestamp services,and uses a random algorithm to elect the master timestamp server to provide services such as accepting requests,processing requests,and time synchronization for the distributed timestamp mechanism.The timestamp is calculated by using a continuous verifiable delay function,and the validity of the timestamp can be easily verified.Finally,blind signatures based on elliptic curves improve the credibility of signatures in distributed timestamp servers.The experimental results show that the security of the blockchain distributed timestamp scheme based on the continuous verifiable delay function is improved,and the efficiency of the timestamp scheme is higher at the same time.(3)Innovation 2 addresses the problems of poor randomness of random numbers in the blockchain,difficulty in outsourcing service calculation,and centralization of multiple nodes.This thesis further studies the existing random number generation scheme based on blockchain,and proposes a blockchain random number generation scheme based on trapdoor verifiable delay functions.The verifiable delay function is used to realize the completely random and unpredictable random number,the calculation of outsourcing service and the function of off-line node computing power.And perform the task allocation calculation with the trapdoor verifiable delay function,and the outsourcing service improves the performance of the node.The calculation process of the trapdoor verifiable delay function uses distributed computing to share the burden,and the outsourcing service improves the performance of nodes.Finally,this article proves the feasibility of this application scheme through safety analysis and simulation experiments of verifiable delay functions.