Distributed data possession checking for securing multiple replicas in geographically-dispersed clouds

Abstract

Distributing multiple replicas in geographically-dispersed clouds is a popular approach to reduce latency to users. It is important to ensure that each replica should have availability and data integrity features; that is, the same as the original data without any corruption and tampering. Remote data possession checking is a valid method to verify the replicas's availability and integrity. Since remotely checking the entire data is time-consuming due to both the large data volume and the limited bandwidth, efficient data-possession-verifying methods generally sample and check a small hash (or random blocks) of the data to greatly reduce the I/O cost. Most recent research on data possession checking considers only single replica. However, multiple replicas data possession checking is much more challenging, since it is difficult to optimize the remote communication cost among multiple geographically-dispersed clouds. In this paper, we provide a novel efficient Distributed Multiple Replicas Data Possession Checking (DMRDPC) scheme to tackle new challenges. Our goal is to improve efficiency by finding an optimal spanning tree to define the partial order of scheduling multiple replicas data possession checking. But since the bandwidths have geographical diversity on the different replica links and the bandwidths between two replicas are asymmetric, we must resolve the problem of Finding an Optimal Spanning Tree in a Complete Bidirectional Directed Graph, which we call the FOSTCBDG problem. Particularly, we provide theories for resolving the FOSTCBDG problem through counting all the available paths that viruses attack in clouds network environment. Also, we help the cloud users to achieve efficient multiple replicas data possession checking by an approximate algorithm for tackling the FOSTCBDG problem, and the effectiveness is demonstrated by an experimental study.

Verifying multiple replica possession with public key segment under public cloud storage environment

“…Considering that bandwidths are asymmetric between geographically distributed sites, distributed multiple replicas data possession checking (DMRDPC) scheme 13 is proposed to improve challenging cost at both sides. At first, an optimal spanning tree needs to be found in a complete bidirectional directed graph.…”

“…Obviously, the cost for both replica generating and proof validating will grow linearly to the number of replicas. Another alternative is to improve existing single data possession proving solutions to solve MR‐PDP problem 4,12,13 . However, they are either lack of efficiency, because each replica should be validated one by one.…”

Developing IntegrityCatalog, a software system for managing integrity‐related metadata in digital repositories

“…Our solution is orthogonal to external audits by the owner of the objects, or by an external auditor . It is also complementary to encrypted storage of files in the cloud, with schemes such as the one in Samanthula et al…”