| As a new type of network computing paradigm,Cloud Computing has been consistently followed by the academic and industrial.Although cloud computing is considered as the next-generation Internet service paradigm,data security and dependable computing are still the major challenges that currently limit its further development.In order to deal with these problems,many scholars have done a lot of research on data security storage and trusted computing in the cloud environment.Many algorithms and models,like integrity checking and secure multiparty computation(MPC)and so on are proposed.However,many of them have high complexity or lack flexibility.In this paper,blockchain is used to improve this problem.Blockchain is a new trustless distributed computing paradigm.Its core design idea is decentralization.In recent years,as the digital currencies like Bitcoin and Ethereum become more and more popular,blockchain technology is known by many people.Applying blockchain technology to cloud computing,combining the respective advantages of blockchain and cloud computing is a promising application scheme.On the one hand,it can supply more efficient security protecting and integrity checking.On the other hand,it can also help to achieve a wider range of secure multi-party computation.The followings are main research completed in this paper:1.A protection scheme of cloud data security based on blockchain is proposed in this paper.We studied the types and algorithmic process of the typical data integrity checking mechanism,analyzed the data structure in blockchain and the characteristics of the common tree structure.Proposed improved multi-branch Merkle hash tree structure based on B+ tree,described and analyzed its construction process.A data integrity verification scheme based on PDP and a protection and recovery scheme of cloud data are proposed.Studied the secure mechanism and “bloating problem” of Blockchain,and then proposed a metadata-based blockchain scheme which is used to construct a cloud data security protection and recovery model.2.Proposed a blockchain-based secure multiparty computation scheme.Studied the cryptographic algorithms,consensus mechanisms and incentive mechanisms in the blockchain,as well as the general processes of secure multiparty computing schemes and the related typical cryptographic algorithms.Studied on log-based blockchain scheme which is applied into secure multiparty computation.Using the consensus and incentive mechanisms to implement a more efficient and scalable secure multiparty computation scheme.3.Design experiments based on the CloudSim which is used as cloud computing simulation platform,and functionally tested the performance of the data integrity checking scheme and the secure multiparty computing scheme.And compare the proposed schemes with traditional schemes. |
