File system to support secure cloud-based sharing

Cloud storage is a common platform for multiple users to share data over the Internet. It offers a huge storage capacity at low cost and an easy-to-access interface for all users. However, data protection is considered to be an issue, especially for highly secret information. Users usually trust cloud storage providers who do not leak information, but the administrator and tools they use can access arbitrary storage data. One approach against these problems is encrypting files stored in cloud storage. Using encryption, files are kept confidential, but this requires a complicated procedure and understanding of some specific level of cryptography. In this paper, we propose a secure cloud filesystem that enables files to be encrypted and decrypted transparently when storing to or extracting from the filesystem. Each file is protected using a key-based encryption mechanism, and the keys are also stored on the cloud filesystem in secure indexed with the pathname of the target files. This enables users to easily use secure cloud storage that maintains confidentiality and share data using multiple cloud storages without the users needing special knowledge on encryption.