Research On Blockchain Technology Based On Digital Content Protection

Blockchain technology has developed rapidly since Bitcoin was proposed in 2008,and is gradually being used as a trusted distributed ledger in the field of financial and digital content protection.As the use of permissioned blockchains becomes more widespread,consensus algorithms in distributed systems are increasingly being used in the blockchain consensus mechanism.Dealing with massive data transactions raises new requirements of real-time safety of blockchains.The celebrated Raft consensus algorithm perfectly solves the problem of maintaining the consistency in a master-slave cluster,but it cannot guarantee the real-time safety of a permissioned blockchain system in terms of copying with frequent client requests.In this work,we summarize common consensus protocols for permissionless blockchains and permissioned blockchains,and analyze the limitations of Raft in some real-time cases.We propose a new consensus protocol called Dynasty which enhances the assurance of the real-time safety and liveness of permissioned blockchains under all non-Byzantine conditions.The Dynasty consensus protocol is designed to increase system throughput and reduce transaction latency where two-phase commit and view change are used to ensure correctness.We design and implement a three-layer permissioned blockchain named D-Chain with consensus,storage and query layers based on Dynasty consensus protocol.The three-layer architecture enhances the system's robustness and versatility,allowing the system to tolerate f faults when the number of correct nodes is not less than 2f+1.We demonstrate two application models of D-Chain of digital content protection to show the blockchain as a service: used car trading management and real estate registration,and elaborated on the versatility of D-Chain's system design and architecture in the protection of common digital content.Last,we evaluate some performance tests on DChain in terms of throughput,latency,and node scalability.Experimental results show that while the latency in different scales of the system increases as expected,the number of committed transactions per second stabilizes at a point within less than 8% difference after a warming-up period.