云计算环境下群组数据共享的隐私保护研究

本项目针对公共云存储环境下群组数据共享的隐私保护需求，重点研究支持动态群组和动态权限的数据高效加密机制和群组共享数据完整性的公开验证机制。通过融合广播加密、基于属性加密、加解密计算部分外包以及基于变色龙hash的密钥推导机制降低用户终端进行加密密钥封装机制的计算和通信开销，支持以数据创建者为中心的动态群组、属性和权限管理；通过构造新的同态可验证群签名方案及安全模型和构造支持同态可验证的代理重签名方案，实现对动态群组和动态共享数据的高效完整性公开验证，同时对验证方保护群组用户的身份隐私。本项目研究将为基于公共云存储的群组应用（如社会网络、数据共享）提供用户数据内容和群组中用户身份的隐私保护手段，相关研究内容均处于当前国际学术研究的前沿，同态可验证群签名等研究内容尚未见报导。因此本项目研究具有重要的理论意义和广泛的应用前景，对推动云计算的发展有积极的促进作用。

It is urgent to provide efficient privacy-preserving methods for group data sharing in the public cloud storage environment. We will focus our research on two aspects. One is efficient Key Encapsulation Mechanism (KEM) supporting dynamic group and data-owner centralized dynamic privilege management. The other is public auditing mechanism for shared data with large scalable group. We will combine broadcasting encryption, attributed based encryption, partially outsourcing encryption and decryption, and Chameleon hash based key derivation mechanism to reduce the computation and communication overhead for user terminal, as well as to support data owner centralized dynamic group, attribute and privilege management. On the other hand, we will propose new homomorphic verifiable group signature method and its security model, and construct proxy re-signature schemes supporting homomorphic verification. Based on homomorphic verificable group signature and proxy re-signature, we will present efficient public auditing protocol which can protect user identity privacy in the group from verifier, support dynamic group and dynamic shared data modification. Our research will provide privacy protection methods for user's data and identity in the group sharing application based on public cloud storage environment, such as social network and data sharing. The researches are in the frontier of this area. To best of our knowledge, partial research contents, such as homomorphic verificable group signature, are not available in existing literatures up to now. Therefore, our research is both theoretically and practically valuable. We believe it will be an important contribution the development of cloud computing.