开放式结构和异构客户端的特点使得云平台需要支持跨域服务。然而由于基于云平台的数据和身份隐私保护研究的缺乏，导致现在的云平台系统并不能提供面向异构用户的安全跨域服务。本项目研究开放式云平台中基于跨域用户的数据隐私保护技术，从理论与实践上解决跨域用户的数据隐私保护问题。首先，通过研究隐私保护数据发布技术，建立满足云平台系统用户个性化需求的匿名模型；其次，深入研究无证书密码方案，特别是具有特殊属性的无证书密码方案，以设计个性化匿名策略；再次，采用无证书密码技术，设计满足不同需求的隐私保护协议，结合标准模型下安全的无证书密码方案，构建面向云平台数据服务系统的组合安全策略；最后，采用基于熵关联性度量和基于分布概率度量相结合的方法，建立移动跨域云平台系统隐私保护水平的评估机制。本项目的实施将有利于推动云计算及大数据产业的发展。

Because the nature of open architecture and heterogeneous clients of cloud platform, cross-domain services are needed. However, due to the lack of researches on data and identity privacy preservation on cloud platform, existing cloud platform systems cannot provide secure cross-domain services for heterogeneous users. This project studies data privacy preservation techniques based on cross-domain users on open cloud platform, aims at solving problem of cross-domain user’s data privacy preservation theoretically and practically. First, we will establish an anonymity model that meets user’s individual needs by studying the techniques of privacy-preserving data publishing. Second, we will study certificateless cryptography schemes, especially those with special properties, to design individual anonymity strategies. Third, we will adopt the certificateless cryptography techniques to the design of privacy-preserving protocols which meet different needs, and employ the secure certificateless cryptography schemes of standard model to build a combined security policy for data service systems on cloud platform. Finally, we will combine the methods of entropy correlation and probability distribution measurement to build evaluation mechanism of privacy preservation level for mobile cross-domain cloud platform systems. The implementation of the project will promote the development of cloud computing and big data industry.