Towards Secure and Dependable Cloud Storage Based on User-Defined Workflows

A major concern of users of cloud storage services is the lost of control over security, availability and privacy of their files. That is partially addressed by end-to-end encryption techniques. However, most of the solutions currently available offer rigid functionalities that cannot be rapidly integrated into customized tools to meet user's requirements like, for example, file sharing with other users. This paper presents an end-to-end architecture that enables users to build secure and resilient work-flows for storing and sharing files in the cloud. The workflows are configurable structures executed on the user-side that perform processing operations on the files through chained stages such as data compression for capacity overhead reduction, file assurance for ensuring confidentiality when sharing files and information dispersion for storing files in n cloud locations and retrieving them even during outages of m cloud storage providers. The users can set up different workflows depending on their requirements because they can organize the processing units of each stage in either pipeline to improve its performance or stack for improving functionality. The stages and their processing units are connected using I/O communication interfaces which ensure a continuous data flow from the user/organization computers to multiple cloud locations. Based on our architecture, we developed a prototype for a private cloud infrastructure. The experimental evaluation revealed the feasibility of enabling flexible file sharing and storage user-defined workflows in terms of performance.