一种高效安全的去中心化数据共享模型

An Efficient and Secure Decentralizing Data Sharing Model

数据开放共享是推动数据相关产业发展的源动力,然而,现有的数据共享模型,如数据市场,数据提供方将数据上传至数据存储中心,数据需求方下载数据以实现分析.这种模型存在如下缺陷:(1)以关键字为基础的数据检索无法高效发现可连接数据集;(2)数据交易缺乏透明性,无法有效检测及防患交易参与方串谋等舞弊行为;(3)数据所有者失去数据的控制权、所有权,数据安全无法保障.为此,该文借助区块链技术建立一种全新的去中心化数据共享模型.首先从共享数据集中提取多层面元数据信息,通过各共识节点建立域索引,以解决可连接数据集的高效发现问题;其次,从交易记录格式及共识机制入手,建立基于区块链的数据交易,实现交易的透明性及防串谋等舞弊行为;最后,依据数据需求方的计算需求编写计算合约,借助安全多方计算及差分隐私技术保障数据所有者的计算和输出隐私.实验结果表明,该文提出的域索引机制在可接受的召回率范围内,连接数据集查准率平均提高22%.而以时间及交易区块数相结合的共识机制则能兼顾低交易频率与高交易频率双重需求.同时,与加密方式相比,在保证数据安全的前提下,该文提出的安全计算模型平均节省了近6秒的处理时间.

Data opening and sharing is the source power for driving the development of data-related industries.However,the typical data sharing model available at present,e.g.,data market,in which data providers upload their data to a centralized repository and data demanders download their requested data to carry out analysis,has the following flaws:(1)As only considering the frequency of keyword in each dataset(or dataset name),the keyword-based dataset retrieval method,which widely used nowadays,cannot efficiently find the linkable datasets.(2)Being lack of transparency in the process of data transactions,the current data trading model does not take full account of detecting the transaction collusion or other frauds among the involved parties.(3)The data owners lose the power of controlling their own data,which causes no guarantee of data ownership and data security.We found out that these problems exposed in the process of data sharing could be attributed to three factors:linkable dataset discovery,data transaction management,computing security and output security.For the purpose of solving them efficiently and effectively,we proposed a novel blockchain-based decentralization data sharing model,which characterized by followings:(1)It was inspired by restoring data providers greater control over their own data by means of DataSpace(DS).(2)The computation or analysis was completed confidentially among the data providers,instead of in the data demanders,or in the third parties,as the latter two needed to download data into their own spaces which become the source of privacy leak.(3)It obtained computing datasets or tasks through domain indexing and interface mechanisms,and controlled user behavior and data flow by the blockchain technology.Concretely,in this paper,we first introduced the basic conception of the decentralized data sharing model based on the analysis of the traditional data sharing model.Then,we showed the hierarchical structure diagram of decentralized data sharing model,which included interface,transaction,index,and data layers.Finally,we analyzed the related technologies and implementation details of each layer respectively:In the interface layer,we obtained computing datasets through domain searching mechanism,and compiled the computation contract according to the requirements of the data demanders.In the index layer,we extracted multi-aspect metadata information from the shared dataset,and had the consensus nodes set up domain index to search linkable datasets efficiently.In the transaction layer,with the help of consensus mechanism,we implemented data transaction based on blockchain to achieve transparency and to prevent conspiracy.In the data layer,we introduced the computation contract,which assembled the secure multi-party computation and differential privacy,to ensure the computation and output privacy of the data providers.The experimental results show that the domain index mechanism proposed in this paper increases the average precision by 22%without substantially reducing the recall rate.And the modified consensus mechanism,which combines time and transaction block number,takes both low trading frequency and high trading frequency into account.At the same time,on the premise of ensuring data security,comparing with the encryption method,our method saves the processing time of nearly 6 s.