作为云计算所提供的一项重要服务，云数据共享非常具有吸引力。然而，使用这些服务的个人和组织仍然非常担忧自己的隐私和数据的安全。本项目主要研究云数据共享中具有隐私保护的访问权限授权技术。首先，为了在保护用户属性隐私的同时，从事前防范的角度对访问权限的滥用进行限制，将着重研究密钥进化的匿名的属性基加密技术和直接可撤销的匿名的属性基加密技术。其次，为了在保护用户属性隐私的同时，从事后追踪的角度对访问权限的滥用进行限制，将着重研究公开可追踪的匿名的属性基加密技术。最后，为了同时实现隐私保护和访问权限的更新，将着重研究匿名的属性基代理重加密技术。这些关键技术将有助于提升用户对云数据共享的信任度，对促进云计算健康、快速、长期的发展有着重要的意义。随着云存储技术的快速发展，云数据共享将越来越经济和方便。因此，本项目的研究不仅具有重要的理论价值，而且具有广阔的应用前景。

As a significant service of cloud computing, cloud-based data sharing is extremely attractive. However, privacy and data security still are major concerns for individuals and organizations using such services. In this project, we mainly focus on the research on privacy-preserving authorization techniques of access privileges in cloud-based data sharing. Firstly, in order to limit the access privilege abuse from the point of prevention while protecting users' attribute privacy, both key-evolving anonymous attribute-based encryption and directly-revocable anonymous attribute-based encryption schemes are proposed. Secondly, to limit the abuse from the point of accountability in a privacy-preserving way, an anonymous attribute-based encryption scheme with public traceability is constructed. Finally, in order to realize privacy protection and access privileges update simultaneously, anonymous attribute-based proxy re-encryption is researched. These key techniques can improve the trust level of users on cloud-based data sharing, and play an important role in the sound, fast and long-term development of cloud computing. With the rapid development of cloud storage technologies, data sharing has never been more economical and convenient than now. Therefore, this project is crucial not only in the theoretical research, but also in real-world applications.