| In recent years,technologies centered on artificial intelligence,5G,big data,and the Internet of Things are affecting the world,causing some problems regarding the storage,sharing and transaction of massive data.The emergence of blockchain solves the above problems.However,blockchain suffers from data redundancy,huge communication and computation cost.In addition,this technology has some disadvantages,such as heavy burden on nodes and user in the transaction process.To this end,we propose a lightweight optimization solution for blockchain,in terms of data storage,sharing and transaction.First,a blockchain architecture that optimizes the storage capacity is proposed,based on with blocks and nodes store data in groups.Then,a lightweight block data sharing and verification scheme is proposed for sharing.Finally,we propose an incentive and trading mechanism that reduces the burden on nodes and user.The main contributions in this dissertation can be summarized as follows:(1)In order to reduce the degree of data redundancy and achieve the lightweight storage,we propose an expansion algorithm based on packet-allocation to store data.Under the premise of ensuring data security,this algorithm groups blocks and assigns tasks to nodes.This method divides nodes into full nodes,lightweight nodes and witness nodes based on comprehensive scores.The changes of node functions when new nodes join in and old nodes exit the blockchain are discussed in detail.The experimental results show that the algorithm can save the data storage space of nodes.(2)In order to reduce the communication and calculation costs in the shared link and realize the lightweight sharing,we propose a secure data sharing and verification mechanism based on the identity-content block.First,the mechanism introduces the identity proof block and content block to blockchain.Then,user can reduce the volume of verification through customized identifiers.Finally,a complete data verification process is designed.If the data receiver does not obtain all of the original data,this proposal can be used as a remedial measure.The experimental results show that the identity proof block and the content block can reduce the communication and computation costs,and the method only takes a short time.(3)In order to reduce the bandwidth pressure of node when processing transactions and save user costs,for achieving the lightweight transactions,we propose a prepaid incentive and trading mechanism based on access frequency and bandwidth availability.This mechanism subdivides the price for different periods and data types according to the frequency of data access and the availability of bandwidth.Then,credibility,bandwidth transaction probability,and advance payment are considered when evaluating the node honesty.The pre-cost ensures that both parties are trustworthy,thereby reducing the losses.Finally,in order to improve the transaction performance and increase the throughput,only the signatures of both parties are required to verify the transaction,and the mechanism only needs to pay fees when the transaction is open and closed.The experimental results show that this mechanism reduces the user’s overhead and increases the throughput of transactions. |
