Abstract: The technical characteristics of de-centered,de-trust,data complete and traceable of block chain provide brand-new opportunity and challenge for cloud computing.Users get computing,storage,database and other resources from the traditional centralized data center through network.There are many problems under this model,such as high operating cost,low efficiency,unsafe data storage and so on.In this paper,a de-centered cloud computing trading mechanism and method was proposed to build a cloud computing resource trading market based on block chain technology,focusing on the application of consensus mechanism in the central cloud computing trading market.Through the analysis and comparison of the popular block chain consensus algorithms (Pos,PoW,DPoS,PBFT),this paper proposed the improved practical byzantine fault-tolerant algorithm (PBFT),which is employed to optimize the disadvantages of resource waste and trust loss when the etheric square is applied to the alliance chain,so as to reduce the cost,and apply the improved algorithm to the central trading market of cloud computing resources.This paper proposed to introducte block chain technology in cloud computing resource trading,and collectively maintain a reliable distributed database by means of de-centered and de-trust.The design of a consensus mechanism based on Ethernet can build a global Internet computing power trading platform,thus realizing the elastic scalability and on-demand allocation of cloud computing resources.

Key words: Block chain, Cloud computing transactions, Consensus mechanism, Etheric fang, Practical Byzantine fault-tolerant algorithm