SaTC: CORE: Medium: Collaborative: Scalable Dynamic Access Control for Untrusted Cloud Environments

当用户将他们的数据存储在云中时，他们承担了许多隐私风险：云存储提供商会允许其他人查看这些数据吗？如果用户为数据设置了共享规则，云存储系统会遵循这些规则吗？最近有关用户数据从云存储系统中外泄的新闻报道表明，用户有理由感到担忧。在将文件存储在云中之前对文件进行加密将提供强大的保护，但这种方法使用户很难与他人共享数据，也很难改变他们的共享策略。该项目正在探索对基于云的存储系统中的用户文件进行加密保护的技术，同时支持高级的动态共享策略。尽管文献中很好地记录了在静态访问控制策略下对数据进行加密保护的情况，但现有的结构要么不能有效地支持动态策略(例如，角色/属性分配的改变)，要么做出严重的信任假设来支持这种动态性。该项目正在(1)开发一个开源平台，用于原型、分析和部署针对不可信环境的动态访问控制实施解决方案；(2)创建能够在不可信的存储平台上安全地实现流行的基于角色和属性的访问控制模型的密码结构，同时支持动态策略和数据更新；(3)设计在各种部署场景中支持动态策略和数据更新的高效、可信的硬件辅助的、云规模的流行访问控制模型的实现；以及(4)进行全面的评估，探索这些加密和硬件强制实施的方法之间的信任权衡，并检查在各种真实世界工作负载下所提议的构造的加密、计算和通信成本。

When users store their data in the cloud, they take many privacy risks: Will the cloud storage provider allow others to see that data? If the user sets sharing rules for the data, will the cloud storage system follow those rules? Recent news stories of user data exfiltration from cloud storage systems show that users have reason for concern. Encrypting files before storing them in the cloud would provide strong protection, but this approach makes it very difficult for users to share data with others and to change their sharing policies. This project is exploring techniques to cryptographically protect user files in cloud-based storage systems, while supporting advanced, dynamic sharing policies.While cryptographically protecting data under a static access control policy is well documented in the literature, existing constructions either do not efficiently support dynamic policies (e.g., changes to role/attribute assignments) or make heavy trust assumptions to support this dynamism. This project is (1) developing an open-source platform for prototyping, analyzing, and deploying dynamic access control enforcement solutions for untrusted environments; (2) creating cryptographic constructions that are capable of securely implementing popular role- and attribute-based access control models on untrusted storage platforms while supporting dynamic policy and data updates; (3) designing efficient, trusted hardware-assisted, cloud-scale implementations of popular access control models supporting dynamic policy and data updates in a variety of deployment scenarios; and (4) a carrying out a comprehensive evaluation that explores the trade-offs in trust between these cryptographically- and hardware-enforced approaches and examines the cryptographic, computational, and communication costs of the proposed constructions under a variety of real-world workloads.