Multiple-Replica Public Auditing Protocol for Cloud Storage

Abstract

Cloud storage can provide a flexible on-demand data storage service to users anywhere and anytime. However, users data is owned by cloud service provider physically, and the physical boundary between two users data is fuzzy. Moreover, cloud storage provider stores multiple replicas of data in order to increase robustness of users data. The user is charged by the amount of replicas. However, the evidence cloud storage provider actually spends more storage space is scarce. In this environment, a method to ensure multi-replica integrity must be provided. In order to avoid retrieving enormous storage data and users themselves checking, a multi-replica public auditing protocol was proposed based on the BLS short signature scheme and the homomorphic hash function. Based on the computational Diffie-Hellman assumption, the presented protocol is secure against the lost attack and tamper attack from cloud service provider. As the independence among blocks and block signatures, this protocol supports block-level dynamic update, including insertion, modification and deletion. So, the protocol is secure and efficient, and supports for multi-replica, public verification, dynamic update and privacy preserving.