Implementation of a secure and reliable storage above the untrusted clouds

Cloud Computing as a service-on-demand architecture has grown in importance over the previous few years. One driving force of its growth is the ever increasing amount of data which is supposed to outpace the growth of storage capacity. This way, public cloud storage services enable organizations to manage their data with low operational expenses. However, the benefits of cloud computing come along with challenges and open issues such as security, reliability and the risk to become dependent on a provider for its service. In general, a switch of a storage provider is associated with high costs of adapting new APIs and additional charges for inbound and outbound bandwidth and requests. In this paper, we describe the design, architecture and implementation of Cloud-RAID, a system that improves availability, confidentiality and integrity of data stored in the cloud. To achieve this objective, we encrypt user´s data and make use of the RAID-technology principle to manage data distribution across cloud storage providers. Our approach allows users to avoid vendor lock-in, and reduce significantly the cost of switching providers. In general, the data distribution is based on users´ expectations regarding providers geographic location, quality of service, providers reputation, and budget preferences. In this paper, we also discuss the security functionality and reveal our observations on the overall performance when encrypting and encoding user´s data.