Core features of the blockchain technology are "de-centralization" and "de-trusting" .As a distributed ledger technology ,smart contract infrastructure platform and novel distributed computing paradigm ,it can effectively build programmable currency ,programmable finance and programmable society ,which will have a far-reaching impact on the financial and other fields ,and drive a new round of technological change and application change .While blockchain technology can improve efficiency , reduce costs and enhance data security ,it is still in the face of serious privacy issues which have been widely concerned by researchers . The survey first analyzes the technical characteristics of the blockchain ,defines the concept of identity privacy and transaction privacy ,points out the advantages and disadvantages of blockchain technology in privacy protection and introduces the attack methods in existing researches ,such as transaction tracing technology and account clustering technology .And then we introduce a variety of privacy mechanisms ,including malicious nodes detection and restricting access technology for the network layer ,transaction mixing technology ,encryption technology and limited release technology for the transaction layer , and some defense mechanisms for blockchain applications layer .In the end ,we discuss the limitations of the existing technologies and envision future directions on this topic .In addition ,the regulatory approach to malicious use of blockchain technology is discussed .%区块链技术的核心特征是"去中心化"和"去信任化",作为分布式总账技术、智能合约基础平台、分布式新型计算范式,可以有效构建可编程货币、可编程金融和可编程社会,势必将对金融及其他领域带来深远影响,并驱动新一轮技术变革和应用变革.但是区块链技术在提高效率、降低成本、提高数据安全性的同时,也面临严重的隐私泄露问题,得到研究者的广泛关注.将介绍区块链技术架构,定义区块链技术中身份隐私和交易隐私的概念,分析区块链技术在隐私保护方面存在的优势和不足,并分类描述现有研究中针对区块链隐私的攻击方法,例如交易溯源技术和账户聚类技术;然后详细介绍针对区块链网络层、交易层和应用层的隐私保护机制,包括网络层恶意节点检测和限制接入技术、区块链交易层的混币技术、加密技术和限制发布技术,以及针对区块链应用的防御机制;最后,分析了现有区块链隐私保护技术存在的缺陷,展望了未来发展方向.此外,还讨论针对恶意使用区块链技术的监管方法.
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