Research On Key Technology And Its Applications Of Blockchain

As a new distributed computing paradigm,blockchain technology has the characteristics of decentralization,collective maintenance supervision,security and credibility,traceability and programmability,and can realize the transformation of information Internet to value Internet.In the future,blockchain technology can be widely used in many fields,such as finance,intellectual property,and the Internet of Things.As the earliest application of blockchain technology,bitcoin can realize a decentralized monetary system.However,it requires that all transaction records must be published to the network,which will significantly increase the risk of the trader's privacy leakage.Besides,if an account owner's private key is lost,his bitcoin will not be consumed.Therefore,it is meaningful to research on the transaction privacy and account security in the bitcoin system.In addition,in the existing outsourcing computation,a trusted third party is required to ensure the fairness.However,it is difficult and expensive to build the trusted third party in a network environment.Therefore,it is worth replacing the third party with the blockchain smart contract technology to ensure the fairness of outsourcing computation.To solve the above problems,the main work of this thesis is:1.A new scheme was proposed to ensure the transaction privacy and account security for bitcoin.The proposed scheme can achieve the complete hiding of the transaction amount and the output address by employing the homomorphic Paillier cryptosystem and one time address mechanism,and thus effectively protect the privacy of transactions in bitcoin.At the same time,Shamir threshold scheme,which distributes a private key to multiple authorized participants,is used to ensure that the private key can be recovered even if the account owner's private key is lost,which can enhance the security of the account.Security analysis shows that the proposed scheme can achieve the confidentiality of the transaction information,non-tampering,and the unforgeability of the signature.2.Based on the blockchain smart contract technology,this paper presented a new fair payment scheme for secure outsourcing computation of linear programming without relying on any third party.The proposed scheme enables an automatic penalty to anyone who does not honestly execute the protocol by using the smart contract technology,which can ensure the fairness of outsourcing computation without the participation of any trusted or semi-trusted third party.At the same time,the correctness of outsourcing computation can be verified by the miners,which replaces the verification overhead of the cloud users.Security analysis shows that the proposed scheme can resist the distributed denial of service attacks,the eavesdropping attacks,the tampering attacks,and achieve the confidentiality,verifiability,completeness and fairness of outsourcing problem.