With the rapid development of Internet technology, many traditional auctions are gradually replaced by electronic auctions, and the security privacy protection problem in them becomes more and more concerned. Concerning the problems in the current electronic bidding and auction systems, such as the risk of the privacy of bidder being leaked, the expensive cost of third-party auction center is expensive, and the collusion between third-party auction center and the bidder, a sealed-bid auction scheme based on blockchain smart contract technology was proposed. In the scheme, an auction environment without third-party was constructed by making full use of the features of the blockchain, such as decentralization, tamper-proofing and trustworthiness; and the security deposit strategy of the blockchain was used to restrict the behaviors of bidders, which improved the security of the electronic sealed-bid auction. At the same time, Pedersen commitment was used to protect auction price from being leaked, and Bulletproofs zero-knowledge proof protocol was used to verify the correctness of the winning bid price. Security analysis and experimental results show that the proposed auction scheme meets the security requirements, and has the time consumption of every stage within the acceptable range, so as to meet the daily auction requirements.

Smart contract is one of the core technologies of blockchain,and its security and reliability are very important. With the popularization of blockchain application,the number of smart contracts has increased explosively. And the vulnerabilities of smart contracts will bring huge losses to users. However,the current research focuses on the semantic analysis of Ethereum smart contracts,the modeling and optimization of symbolic execution,and does not specifically describe the process of detecting smart contract vulnerabilities using symbolic execution technology,and how to detect common vulnerabilities in smart contracts. Based on the analysis of the operation mechanism and common vulnerabilities of Ethereum smart contract,the symbol execution technology was used to detect vulnerabilities in smart contracts. Firstly,the smart contract control flow graph was constructed based on Ethereum bytecode,then the corresponding constraint conditions were designed according to the characteristics of smart contract vulnerabilities,and the constraint solver was used to generate software test cases to detect the common vulnerabilities of smart contracts such as integer overflow,access control,call injection and reentry attack. The experimental results show that the proposed detection scheme has good detection effect, and has the accuracy of smart contract vulnerability detection up to 85% on 70 smart contracts with vulnerabilities in Awesome-Buggy-ERC20-Tokens.

Aiming at the communication problem of crossing the rack switches for a large amount of intermediate data generated after the Map phase in the MapReduce process, a new optimization method was proposed for the map-intensive jobs. Firstly, the features from the pre-running scheduling information were extracted and the data communication activity was quantified. Then naive Bayesian classification model was used to realize the classification prediction by using the historical jobs running data to train the classification model. Finally, the jobs with active intermediate data communication process were mapped into the same rack to keep communication locality. The experimental results show that the proposed communication optimization scheme has a good effect on shuffle-intensive jobs, and the calculation performance can be improved by 4%-5%. In the case of multi-user multi-jobs environment, the intermediate data can be reduced by 4.1%. The proposed method can effectively reduce the communication latency in large-scale data processing and improve the performance of heterogeneous clusters.

The routing scheme is one of the key factors which influence the lifetime of Wireless Sensor Network (WSN). The network can be paralyzed easily as a result of large energy consumption of key nodes by heavy communication. To solve the problem of energy consumption of key nodes in WSNs, a new ant colony routing algorithm on Dynamic Adjustment of Forward Angle based on Residual Energy (DAFARE) was proposed. Firstly, the nodes chose the next-hop node according to residual energy and distance in the range of initial forward angle; secondly, the forward angle was adjusted dynamically in the view of residual energy of nodes within the scope of forward angle; finally, early death of key nodes was avoided successfully. The simulation suggested that the effective life could be improved approximately 50% by DAFARE, compared with ant colony optimization algorithm based on Function of Multi-object Evaluation and Positive-Negative Feedback (FMEPNF). The experimental results show that, the network energy consumption of DAFARE can be balanced effectively, the lifetime is prolonged, and the coverage of WSN is guaranteed.