Secure Outsourcing and Sharing of Cloud Data Using a User-Side Encrypted File System

Cloud computing is an emerging paradigm that aims to provide computing resources, massive data storage capacity and, flexible data sharing services. The explosive growth of data produced persuade business and users, driven by the cloud-top features, to outsource their data to the cloud storage systems. However, the confidentiality and integrity of outsourced sensitive data in remote cloud servers are becoming a major concern. Data must be encrypted prior to storing it in the, potentially untrustworthy cloud. Existing traditional encryption systems impose a heavy burden of managing files and encryption operations on data owners. They suffer from serious security, efficiency, and usability issues, and some schemes are inappropriate for protecting cloud data. In this paper, we introduce OutFS, a user-side encrypted file system, focused on providing a transparent encryption for stored and shared outsourced data. In OutFS, we utilize a hybrid encryption scheme structure based on symmetric and asymmetric methods. The key management is conveniently designed. In order to ensure robust data sharing security, the identity-based encryption scheme (IBE) is integrated with OutFS. OutFS is designed to preserve the integrity of outsourced file data and file system data structure. Analysis of performance and experimental results show that OutFS is efficient. It can achieve an average throughput of 8.8 MB/sec, and 10.5 MB/sec for writing and reading outsourced files. Security analysis indicates that OutFS is extremely secure and robust against attacks such as brute-force, eavesdropping, man-in-the-middle, and offline-dictionary attacks.