19-07-2012, 02:49 PM
Privacy-Preserving Public Auditing for Secure Cloud Storage
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INTRODUCTION
CLOUD Computing has been envisioned as the
next-generation information technology (IT) architecture
for enterprises, due to its long list of unprecedented
advantages in the IT history: on-demand
self-service, ubiquitous network access, location independent
resource pooling, rapid resource elasticity,
usage-based pricing and transference of risk [1]. As
a disruptive technology with profound implications,
Cloud Computing is transforming the very nature of
how businesses use information technology. One fundamental
aspect of this paradigm shifting is that data
is being centralized or outsourced to the Cloud.
PROBLEM STATEMENT
The System and Threat Model
We consider a cloud data storage service involving
three different entities, as illustrated in Fig. 1: the cloud
user (U), who has large amount of data files to be
stored in the cloud; the cloud server (CS), which is
managed by the cloud service provider (CSP) to provide
data storage service and has significant storage space
and computation resources (we will not differentiate
CS and CSP hereafter); the third party auditor (TPA),
who has expertise and capabilities that cloud users
do not have and is trusted to assess the cloud storage
service reliability on behalf of the user upon request.
THE PROPOSED SCHEMES
This section presents our public auditing scheme
which provides a complete outsourcing solution of data
– not only the data itself, but also its integrity checking.
We start from an overview of our public auditing
system and discuss two straightforward schemes and
their demerits. Then we present our main scheme
and show how to extent our main scheme to support
batch auditing for the TPA upon delegations from
multiple users. Finally, we discuss how to generalize
our privacy-preserving public auditing scheme and its
support of data dynamics.
Definitions and Framework
We follow a similar definition of previously proposed
schemes in the context of remote data integrity checking
[8], [11], [13] and adapt the framework for our
privacy-preserving public auditing system.
A public auditing scheme consists of four
algorithms (KeyGen, SigGen, GenProof,
VerifyProof). KeyGen is a key generation
algorithm that is run by the user to setup the
scheme. SigGen is used by the user to generate
verification metadata, which may consist of MAC,
signatures, or other related information that will be
used for auditing.