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FileCrypt: Transparent and Scalable Protection of Sensitive Data in Browser-based Cloud Storage

While cloud storage has become a common practice for more and more organizations, many severe cloud data breaches in recent years show that protecting sensitive data in the cloud is still a challenging problem. Although various mitigation techniques have been proposed, they are not scalable for large scale enterprise users with strict security requirements or often depend on error-prone human interventions. To address these issues, we propose FileCrypt, a generic proxy-based technique for enterprise users to automatically secure sensitive files in browser-based cloud storage. To the best of our knowledge, FileCrypt is the first attempt towards transparent and fully automated file encryption for browser-based cloud storage services. More importantly, it does not require active cooperations from cloud providers or modifications of existing cloud applications. By instrumenting mandatory file-related JavaScript APIs in browsers, FileCrypt can naturally support new cloud storage services and guarantee the file encryption cannot be bypassed. We have evaluated the efficacy of FileCrypt on a number of popular realworld cloud storage services. The results show that it can protect files on the public cloud with relatively low overheads.