Remote Integrity Verification for Multiple Data Copies in Cloud Environments:A Comparative Analysis and Open Research Issues

Every hour many organizations generate terabytes of data, and that may exceed their storage ability. Storing and manipulating such big data is a costly process.That is why outsourcing data storage to remote cloud service providers (CSPs) is currently a preferred storage model to mitigate the burden of local data storage. To achieve a higher level of scalability, availability and durability, some clients ask the CSP to maintain multiple copies of their outsourced data on multiple data centers. In such a case, the clients will be charged more fees. The cloud customers want to make sure that the CSP is not cheating by storing fewer number of data copies. Moreover, all these copies should be consistent with the most recent modifications issued by the clients. The problem of provable data possession (PDP) for multiple data copies has been investigated by many researchers. In this paper, we review the concept of PDP and provide an extensive survey for different provable multi-copy data possession (PMDP) schemes. Moreover, the paper discusses the design principles for various PMDP constructions, highlights some limitations, and present a comparative analysis for numerous PMDP models. In this paper, we focus on two sets on PMDP schemes: protocols for static data, and schemes for dynamic data. The paper also addresses the concept of proof of retrievability, which is a complementary approach to PDP. Furthermore, we highlight some open research issues that need to be investigated and tackled to achieve the wide acceptance and usage of outsourcing data storage.