可验证延迟函数与延迟加密研究综述OA北大核心CSTPCD

Verifiable delay function(VDF)is a novel cryptographic primitive proposed by Boneh et al.in 2018.Whether it is performed in parallel or not,it calculates and outputs the function result at a fixed time of computation,and the verification is fast.In de-centralized applications such as random beacon and blockchain protocols,it can be used to some computational tasks such as repeated squares to provide reliable proof of elapsed time(PoET).This paper focuses on five VDF candidate schemes and their constructions,compares their advantages and disadvantages.It also illustrates their possible problems and characteristics,and describes the applications of VDF in random beacons,resource-efficient blockchains,proof of replication,computation of timestamp,delayed encryption,etc.In particular,the delayed encryption introduced in 2021 is analyzed in detail,and two existing delayed encryption schemes are also analyzed.On the basis of existing VDF studies,this paper summarizes the current state-of-the-art of VDFs and puts forward their views.It shows that Loe et al.P-VDF is the most practical protocol among the five VDF candidates,and it has the advantage of empty proof and efficient validation,and its validation algorithm runs with time complexity O(1).Finally,the development trends and discussion of VDFs are presented.