中文摘要：

随着云存储的迅速推广，有越来越多的用户开始使用网盘系统存放数据.然而，最新的研究结果却表明：现有网盘系统普遍存在着安全漏洞.近年来，网盘泄漏用户数据的事件更是印证了这些漏洞的存在.为此，提出一种云存储环境下的安全网盘系统架构，并在此架构上设计实现了 CorsBox 系统.CorsBox 系统采用一种基于目录树的同步方式，在提高安全性的同时保证了共享操作的最终一致性，为用户提供访问权限控制、大数据断点传输、版本控制等功能.测试结果表明，安全机制仅给系统带来了很少的额外开销，说明CorsBox系统在提高数据安全性的同时依然具有良好的性能.

英文摘要：

With the rapid development of cloud storage, more and more people prefer to store their data in online storage systems. However, recent researches indicate that security problems still remain in current online storage systems, and some recent data leakage accidents of online storage systems also prove the existence of these vulnerabilities. Such security problems seriously hinder the development of online storage system. To address the issue, this study designs and implements a secure online storage system called CorsBox. CorsBox proposes a data synchronous protocol based-on directory trees for fast synchronization between data plaintext and ciphertext, designs a three-level key management scheme to enhance the security of user’s data, and presents an effective method to maintain system eventual consistency. The paper finally conducts a set of intensive experiments on modern servers and the result shows that the security mechanisms only incur a little extra performance expenses, indicating that CorsBox can provide enhanced security for user’s data while maintaining good performance.