25-08-2017, 09:32 PM
A Privacy-Preserving Remote Data Integrity Checking Protocol with Data Dynamics and Public Verifiability
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INTRODUCTION
Storing data in the cloud has become a trend [2], [3].
An increasing number of clients store their important data
in remote servers in the cloud, without leaving a copy in
their local computers. Sometimes the data stored in the
cloud is so important that the clients must ensure it is
not lost or corrupted. While it is easy to check data integrity
after completely downloading the data to be checked,
downloading large amounts of data just for checking data
integrity is a waste of communication bandwidth. Hence,
a lot of works [1], [4], [5], [6], [7], [8], [9] have been
done on designing remote data integrity checking protocols,
which allow data integrity to be checked without completely
downloading the data.
TECHNICAL PRELIMINARIES
We consider a cloud storage system in which there are
a client and an untrusted server. The client stores her data
in the server without keeping a local copy. Hence, it is of
critical importance that the client should be able to verify
the integrity of the data stored in the remote untrusted
server. If the server modifies any part of the client’s data,
the client should be able to detect it; furthermore, any third
party verifier should also be able to detect it.
THE PROPOSED REMOTE DATA INTEGRITY CHECKING PROTOCOL
In this section we describe the proposed remote data
integrity checking protocol. Just as mentioned in Section
II, the proposed protocol has functions SetUp, TagGen,
Challenge, GenProof and CheckProof, as well as functions
for data dynamics. In the following we present the former
five functions of the proposed protocol. We leave the
functions for data dynamics to Section V.
CORRECTNESS AND SECURITY ANALYSIS
In this section, we first show that the proposed protocol is
correct in the sense that the server can pass the verification
of data integrity as long as both the client and the server
are honest. Then we show that the protocol is secure against
the untrusted server. These two theorems together guarantee
that, assuming the client is honest, if and only if the server
has access to the complete and uncorrupted data, it can pass
the verification process successfully. Finally we show that
the proposed protocol is private against third party verifiers.