FMR-PDP: Flexible multiple-replica provable data possession in cloud storage

Cloud storage is a service provided by cloud service provider (CSP). More and more individuals and organizations accept the scheme and outsource their data to CSP seeking to reduce local storage burden. Since the outsourced files are no longer under the data owners' direct control and CSP is not trustworthy, it is necessary for data owners to check the integrity of their files outsourced to CSP. To address this crucial problem, some provable data possession (PDP) protocols have been presented. In order to obtain higher availability, storing multiple replicas is a common strategy in cloud storage. Most recent researches on multiple-replica provable data possession (MR-PDP) use homomorphic linear authenticators (HLAs) to generate aggregated tags for the blocks at the same indices in each replica, but it cannot verify single replica to identify the corrupted replicas. In this paper, we proposed a novel multiple replica provable data possession scheme, named FMR-PDP. In FMR-PDP, we compute tags based on vector dot product instead of expensive group exponentiation operations, and only generate one tag for all blocks at the same indices in each replica. Our FMR-PDP scheme supports a flexible data possession verification, which means the data owner can check any number of replicas in a verification. In addition, we make a comprehensive performance analysis, which shows that our proposed scheme is flexible and efficient.