Verifiable delay functions and delay encryptions from hyperelliptic curves

Verifiable delay functions(VDFs)and delay encryptions(DEs)are two important primitives in decentralized systems,while existing constructions are mainly based on time-lock puzzles.A disparate framework has been established by applying isogenies and pairings on elliptic curves.Following this line,we first employ Richelot isogenies and non-degenerate pairings from hyperelliptic curves for a new verifiable delay function,such that no auxiliary proof and interaction are needed for the verification.Then,we demonstrate that our scheme satisfies all security requirements,in particular,our VDF can resist several attacks,including the latest attacks for SIDH.Besides,resorting to the same techniques,a secure delay encryption from hyperelliptic curves is constructed by modifying Boneh and Frankiln's IBE scheme,which shares the identical setup with our VDF scheme.As far as we know,these schemes are the first cryptographic applications from high-genus isogenies apart from basic protocols,i.e.,hash functions and key exchange protocols.

Blockchain-based continuous data integrity checking protocol with zero-knowledge privacy protection

The cloud computing technology has emerged,developed,and matured in recent years,consequently commercializing remote outsourcing storage services.An increasing number of companies and individuals have chosen the cloud to store their data.However,accidents,such as cloud server downtime,cloud data loss,and accidental deletion,are serious issues for some applications that need to run around the clock.For some mission and business-critical applications,the continuous availability of outsourcing storage services is also necessary to protect users'outsourced data during downtime.Nevertheless,ensuring the continuous availability of data in public cloud data integrity auditing protocols leads to data privacy issues because auditors can obtain the data content of users by a sufficient number of storage proofs.Therefore,protecting data privacy is a burning issue.In addition,existing data integrity auditing schemes that rely on semi-trusted third-party auditors have several security problems,including single points of failure and performance bottlenecks.To deal with these issues,we propose herein a blockchain-based continuous data integrity checking protocol with zero-knowledge privacy protection.We realize a concrete construction by using a verifiable delay function with high efficiency and proof of retrievability,and prove the security of the proposal in a random oracle model.The proposed construction supports dynamic updates for the outsourced data.We also design smart contracts to ensure fairness among the parties involved.Finally,we implement the protocols,and the experimental results demonstrate the efficiency of the proposed protocol.

Workload-based randomization byzantine fault tolerance consensus protocol

This paper introduces a new Byzantine fault tolerance protocol called workload-based randomization Byzantine fault tolerance protocol(WRBFT).Improvements are made to the Practical Byzantine Fault Tolerance(PBFT),which has an important position in the Byzantine Fault consensus algorithm.Although PBFT has numerous ad-vantages,its primary node selection mechanism is overly fixed,the communication overhead of the consensus process is also high,and nodes cannot join and exit dynamically.To solve these problems,the WRBFT proposed in this paper combines node consensus workload and verifiable random function(VRF)to randomly select the more reliable primary node that dominates the consensus.The selection of the nodes involved in the consensus is based on the node workload,and the optimization of the agreement protocol of the PBFT is also based on this.Simulation results show that the WRBFT has higher throughput,lower consensus latency,and higher algorithmic efficiency compared to the PBFT.

Thermal Buckling Analysis of Size-Dependent FG Nanobeams Based on the Third-Order Shear Deformation Beam Theory

In this paper,the thermal effects on the buckling of functionally graded（FG） nanobeams subjected to various types of thermal loading including uniform,linear and non-linear temperature changes are investigated based on the nonlocal third-order shear deformation beam theory.The material properties of FG nanobeam are supposed to vary gradually along the thickness direction according to the power-law form.The governing equations are derived through Hamilton＇s principle and solved analytically.Comparison examples are performed to verify the present results.Obtained results are presented for thermal buckling analysis of FG nanobeams such as the effects of the power-law index,nonlocal parameter,slenderness ratio and thermal loading in detail.