Research On Storage Optimization Scheme For Blockchain

With the development of blockchain technology,it has been applied to more and more business environments,such as traceability systems,Internet of Things,and healthcare,etc.In the public blockchain,each full node needs to store a global ledger,and the data stored in the node will increase with over time.In addition,many recent studies have also begun to focus on the transaction speed of the blockchain.The increase in the speed transaction of blockchain will inevitably lead to a rapid increase in node storage overhead.Moreover,the increasing demand for application data on-chain also provides a foundation for data growth.Therefore,how to reduce the storage overhead of nodes in the blockchain is a very important issue.Currently,there are two main ways to reduce the storage overhead of nodes in blockchain: 1.To change the structure of the existing blockchain system.2.To prune the old data.Changing the existing blockchain system architecture will require the consent of most nodes,which will face security risks such as hard forking of the system.Pruning old data is to directly delete the historical data of the blockchain,which will cause the loss of data and the traceability of the blockchain.Therefore,how to reduce the storage cost of nodes without restructuring the existing blockchain and losing its traceability is a question worth studying.In order to reduce the storage overhead of blockchain nodes,this paper proposes a scheme based on overlay network grouping and coding.The characteristics of the overlay network are used to avoid the reconstruction of the existing blockchain system.And use the coding scheme to make the nodes in the group store only part of the data to achieve the purpose of reducing node storage,while avoiding the direct deletion of data and losing the traceability of the blockchain.The main contents and contributions of this paper are as follows:1.Propose a scheme based on overlay network grouping and coding to solve the problem of large storage capacity of nodes in the blockchain.First,the overall design model is presented,and the workflow of this scheme is explained.Secondly,due to the unrestricted access of nodes in the overlay network of the blockchain,the benefits of constructing a structured overlay network in groups are analyzed.By comparing the copy replication scheme,the advantages of selecting network coding within the group are analyzed.Perform security analysis on the model and point out possible malicious behavior in the scheme.2.Propose a neighboring grouping strategy in the overlay network to apply to the overall scheme.First,perform initial grouping based on the interaction delay to reduce the interaction delay between the nodes in the group.The nodes added after the initial grouping form a group or add a new group according to the size of the delay,so that the nodes in the group have a lower Interaction delay.Secondly,through the group management mechanism,the malicious behavior within the group is suppressed,and the entry and exit of nodes are managed at the same time.Through security analysis,it is demonstrated that the security management mechanism can achieve the state of Nash balance of the nodes in the group,and can effectively suppress malicious behavior.The experiment evaluates that the initial grouping algorithm achieves the effect of reducing the nodes interaction delay within the group,and verifies that the efficiency of the encoded Merkle hash tree generation is milliseconds,and the node bandwidth occupation is also very small that calculated based on the block size of the mainstream blockchain,confirming the availability and efficiency of the grouping strategy.3.Propose a coding scheme based on the transformation of Fractional Repetition code,mainly to deal with the situation where the number of nodes in the traditional coding scheme is fixed and is not applicable to the overlay network grouping in this scheme.First,introduction of Fractional Repetition code,on the basis of which a layered replication method was added to construct the Transcript Fractional Repetition code scheme.Corresponding to the group management rules,repair and manage the nodes that exit and join,and formulate a method for verifying the coded and repairing the faulty node.Secondly,by comparing Fractional Repetition code,it is analyzed that the coding scheme has stronger fault tolerance.The experiment evaluated the speed of encoding and decoding,and confirmed that the efficiency of encoding is very high,and the computing resources occupied are very small.Analyzed the fault tolerance and storage reduction with different parameters of coding,and confirmed that the coding scheme can greatly reduce the storage of nodes while ensuring fault tolerance and codec speed.