Proofs of Data Possession of Multiple Copies

Cloud storage services have quickly gained enormous popularity. They offer great convenience for data storage and sharing. However, since all user data are kept on remote servers and out of user’s control, user may concern about data status. In order to expand storage service, data integrity verification is one of the critical security requirements for cloud storage service to fulfill. In order to verify the integrity status of files on remote cloud servers, many mechanisms have been proposed, such as PDP and POR. However, these methods can only ensure that the remote server holds ONE COPY of user data correctly. In fact, user needs to make sure that there are multiple copies kept on remote servers, incase that the corrupted file parts could not be recovered with a right copy. In this paper, we propose a multi-copy integrity checking scheme, which enables user to verify that HOW MANY COPIES are actually correct in the server. And this scheme could also identify the corrupted file blocks, thus to guide data recovery. Experimental results show that it has better performance comparing with the one copy schemes, owing to the distributing computations to multiple servers.