Proof of Multicopy via Proof of File Position in Cloud

Abstract

For disaster recovery, we store backups of a file in several positions far away from each other. If we delegate this task to an untrusted cloud service provider, a verification method is desired. In this paper, we construct a generic transformation from “proof of retrievability” to “proof of multicopy”. We present this work in two stages. In the first stage, we propose a generic protocol of “proof of file position” based on an arbitrary secure “proof of retrievability” protocol. In the second stage, we propose a “proof of multicopy” protocol based on our “proof of file position” protocol. Both of our protocols are provably secure.