50120140507005 2

International Journal of Computer Engineering and Technology (IJCET), ISSN 0976-6367(Print),
ISSN 0976 - 6375(Online), Volume 5, Issue 7, July (2014), pp. 36-42 © IAEME
INTERNATIONAL JOURNAL OF COMPUTER ENGINEERING
TECHNOLOGY (IJCET)
ISSN 0976 – 6367(Print)
ISSN 0976 – 6375(Online)
Volume 5, Issue 7, July (2014), pp. 36-42
© IAEME:

Journal Impact Factor (2014): 8.5328 (Calculated by GISI)

IJCET
© I A E M E
PRIVACY-PRESERVING PUBLIC AUDITING FOR SECURE CLOUD
STORAGE
Mr. Navanath Jadhav
M.Tech (CSE), Dept.of CSE MLR Institute technology,Dundigal Hyderabad, Telangana-500043
Mrs. L.Laxmi
Asst.Professor, Dept.of CSE MLR Institute technology, Dundigal Hyderabad Telangana-500043
36
ABSTRACT
IT has moved into next generation with cloud computing being realized. The way application
software and databases are stored has been changed. Now they are stored in cloud data centers in
which security is a concern from client point of view. The new phenomenon which is used to store and
manage data without capital investment has brought many security challenges which are not
thoroughly understood. This paper focuses on the security and integrity of data stored in cloud data
servers. The data integrity verification is done by using a third party auditor who is authorized to check
integrity of data periodically on behalf of client.
The client of the data gets notifications from third party auditor when data integrity is lost. Not
only verification of data integrity, the proposed system also supports data dynamics. The work that has
been done in this line lacks data dynamics and true public auditability. The auditing task monitors data
modifications, insertions and deletions. The proposed system is capable of supporting both public
auditability and data dynamics. The review of literature has revealed the problems with existing
systems and that is the motivation behind taking up this work. Merkle Hash Tree is used to improve
block level authentication. In order to handle auditing tasks simultaneously, bilinear aggregate
signature is used. This enables TPA to perform auditing concurrently for multiple clients. Hence here I
are presenting the evaluation of multi user based TPA system. The experiments reveal that the
proposed system is very efficient and also secure.
Index Terms: Data Storage, Privacy-Preserving, Public Auditability, Cryptographic Protocols,
Cloud Computing.

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I. INTRODUCTION
One of the next generations IT Enterprise is Cloud Computing which moves the application
software and databases to the centralized large data centers, where the management of the data and
services may not be fully trustworthy. Several trends are opening up the era of Cloud Computing,
which is an Internet-based development and use of computer technology. The ever cheaper and more
powerful processors, together with the “software as a service” (SaaS) computing architecture, are
transforming data centers into pools of computing service on a huge scale. Meanwhile, the increasing
network bandwidth and reliable yet flexible network connections make it even possible that clients can
now subscribe high quality services from data and software that reside solely on remote data centers.
Although envisioned as a promising service platform for the Internet, the new data storage paradigm in
“Cloud” brings about many challenging design issues which have profound influence on the security
and performance of the overall system. One of the biggest concerns with cloud data storage is that of
data integrity verification at untrusted servers. What is more serious is that for saving money and
storage space the service provider might neglect to keep or deliberately delete rarely accessed data files
which belong to an ordinary client. Consider the large size of the outsourced electronic data and the
client’s constrained resource capability, the core of the problem can be generalized as how can the
client find an efficient way to perform periodical integrity verifications without the local copy of data
files. Considering the role of the verifier in the model, all the schemes presented before fall into two
categories: private auditability and public auditability. Although schemes with private auditability can
achieve higher scheme efficiency, public auditability allows anyone, not just the client (data owner), to
challenge the cloud server for correctness of data storage while keeping no private information. Then,
clients are able to delegate the evaluation of the service performance to an independent third party
auditor (TPA), without devotion of their computation resources. In the cloud, the clients themselves
are unreliable or may not be able to afford the overhead of performing frequent integrity checks.
II. LITERATURE SURVEY
The purpose of this review is to report, evaluate, and discuss the findings from research. A
particular focus of this review is to facilitating privacy-preserving public auditing for secure cloud
storage.
• Mehul A. Shah Ram Swaminathan Mary Baker, A growing number of online services, such as
Google, Yahoo!, and Amazon, are starting to charge users for their storage. Customers often use these
services to store valuable data such as email, family photos and videos, and disk backups. Today, a
customer must entirely trust such external services to maintain the integrity of hosted data and return it
intact. Unfortunately, no service is infallible. To make storage services accountable for data loss, we
present protocols that allow a third party auditor to periodically verify the data stored by a service and
assist in returning the data intact to the customer. Most importantly, our protocols are
privacy-preserving, in that they never reveal the data contents to the auditor. Our solution removes the
burden of verification from the customer, alleviates both the customer’s and storage service’s fear of
data leakage, and provides a method for independent arbitration of data retention contracts.
• Cong Wang, Qian Wang, KuiRen, Wenjing Lou, Cloud Computing has been envisioned as the
next generation architecture of IT Enterprise. In contrast to traditional solutions, where the IT services
are under proper physical, logical and personnel controls, Cloud Computing moves the application
software and databases to the large data centers, where the management of the data and services may
not be fully trustworthy. This unique attribute, however, poses many new security challenges which
have not been well understood. In this article, we focus on cloud data storage security, which has

always been an important aspect of quality of service. To ensure the correctness of users’ data in the
cloud, we propose an effective and flexible distributed scheme with woo salient features, opposing to
its predecessors. By utilizing the homomorphic token with distributed verification of erasure-coded
data, our scheme achieves the integration of storage correctness insurance and data
error localization, i.e., the identification of misbehaving server(s).Unlike most prior works, the new
scheme further supports secure and efficient dynamic operations on data blocks, including: data
update, delete and append. Extensive security and performance analysis shows that the proposed
scheme is highly efficient and resilient against Byzantine failure, malicious data modification attack,
and even server colluding attacks.
• Giuseppe Ateniese, Roberto Di Pietro, Luigi V. Mancini, and Gene Tsudik, Storage
outsourcing is a rising trend which prompts a number of interesting security issues, many of which
have been extensively investigated in the past. However, Provable Data Possession (PDP) is a topic
that has only recently appeared in the research literature. The main issue is how to frequently,
efficiently and securely verify that a storage server is faithfully storing its client’s(potentially very
large) outsourced data. The storage server is assumed to be untrusted in terms of both security and
reliability. (In other words, it might maliciously or accidentally erase hosted data; it might also relegate
it to slow or off-line storage.) The problem is exacerbated by the client being a small computing device
with limited resources. Prior work has addressed this problem using either public key cryptography or
requiring the client to outsource its data in encrypted form. In this paper, we construct a highly
efficient and provably secure PDP technique based entirely on symmetric key cryptography, while not
requiring any bulk encryption. Also, in contrast with its predecessors, our PDP technique allows
outsourcing of dynamic data, i.e., it efficiently supports operations, such as block modification,
deletion and append.
• C. Erway, A. Kupcu, C. Papamanthou, and R. Tamassia, As storage-outsourcing services and
resource-sharing networks have become popular, the problem of efficiently proving the integrity of
data stored at untrusted servers has received increased attention. In the provable data possession (PDP)
model, the client preprocesses the data and then sends it to an untrusted server for storage, while
keeping a small amount of meta-data. The client later asks the server to prove that the stored data has
not been tampered with or deleted (without downloading the actual data). However, the original PDP
scheme applies only to static (or append-only) files. We present a definitional framework and efficient
constructions for dynamic provable data possession (DPDP), which extends the PDP model to support
provable updates to stored data. We use a new version of authenticated dictionaries based on rank
information. The price of dynamic updates is a performance change from O(1) to O(log n) (or O(n
log n)), for a file consisting of n blocks, while maintaining the same (or better, respectively) probability
of misbehavior detection. Our experiments show that this slow down is very low in practice (e.g.,
415KB proof size and 30ms computational overhead for a 1 GBfile). We also show how to apply our
DPDP scheme to outsourced file systems and version control systems (e.g., CVS).
• K.D. Bowers, A. Juels, and A. Oprea, We introduce HAIL (High-Availability and Integrity
Layer), a distributed cryptographic system that permits aset of servers to prove to a client that a stored
file is intact and retrievable. HAIL strengthens, formally unifies, and streamlines distinct approaches
from the cryptographic and distributed-systems communities. Proofs in HAIL are efficiently
computable by servers and highly compact typically tens or hundreds of bytes, irrespective of file size.
HAIL cryptographically verifies and reactively reallocates file shares. It is robust against an active,
mobile adversary, i.e., one that may progressively corrupt the full set of servers. We propose a strong,
formal adversarial model for HAIL, and rigorous analysis and parameter choices. We show how HAIL
38

International Journal of Computer Engineering and Technology (IJCET), ISSN 0976
ISSN 0976 - 6375(Online), Volume 5, Issue 7, July (2014), pp.
36-42 © IAEME
improves on the security and efficiency of
deployed on individual servers. We also report on a prototype implementation
III. IMPLEMENTATION DETAILS
3.1 Existing Work
existing tools, like Proofs of Retrievability
A most important cause of poor website design is that the web developers perceptive of how a
website should be structured and
differences result in cases where users cannot easily find the desired information in a website. This
issue is difficult to handle because when creating a website, web develop
understanding of users’ preferences and can only organize pages based on their own ideas.
Existing System Algorithm
can be considerably different from those of the users. Such
In an existing system k-means algorithm is used for e
structure improvement.
Input: set of k means m1
(1),…,mk
(1)
Assignment step: Assign each observation to the cluster whose mean yields the least within
sum of squares (WCSS). Since the sum of squares is the squared Euclidean, this is intuitively the
nearest mean. (Mathematically, this means partitioning the observations according to the
diagram generated by the means).
Where each is assigned to exactly one
Update step: Calculate the new means to be the
Since the arithmetic mean is a
sum of squares (WCSS) objective.
3.2 Proposed Work
In this project we are presenting and extending the
navigation through website structure improvement
through website structure. This approach delivers the efficiency as
methods for improvement of website
creating website web developers don’t have clear understanding of
project our main aim is to present approaches to overcome the limitations. In this
will add new algorithm which will efficiently do the
structure. For this purpose we are using
39
developers may not have a cl
effective user navigation through website
: , even if it could be is assigned to two or more of them.
: centroids of the observations in the new clusters.
least-squares estimator, this also minimizes the within
Cure clustering algorithm
improvement. The current method is dealing with
. well as effectiveness of proposed
website. However this method is suffered from limitations like
clients’ requirement.
o existing method we
improved user navigation through website
CURE clustering algorithm.
0976-6367(Print),
(PORs)
ers clear
ffective within-cluster
Voronoi
, within-cluster
for user
. user navigation
. while
Thus in this

40
Algorithm
Input: Datasets of real websites
• Random sampling: To handle large data sets, we do random sampling and draw a sample data
set. Generally the random sample fits in main memory. Also because of the random sampling there is
a tradeoff between accuracy and efficiency.
• Partitioning for speed up: The basic idea is to partition the sample space into p partitions. Each
partition contains n/p elements. Then in the first pass partially cluster each partition until the final
number of clusters reduces to n/pq for some constant q 1. Then run a second clustering pass
on n/q partial clusters for all the partitions. For the second pass we only store the representative points
since the merge procedure only requires representative points of previous clusters before computing
the new representative points for the merged cluster. The advantage of partitioning the input is that we
can reduce the execution times.
• Labeling data on disk: Since we only have representative points for k clusters, the remaining
data points should also be assigned to the clusters. For this a fraction of randomly selected
representative points for each of the k clusters is chosen and data point is assigned to the cluster
containing the representative point closest to it.
Output: Set of web links that needs to be redesign and relink.
IV. RESULTS
4.1 Hardware and Software Used
Hardware Configuration
- Processor - PentiumIV 2.6 ghz
- RAM - 512 mbdd ram
- Monitor - 15” color
- Hard Disk - 20 GB
- Key Board - Standard Windows Keyboard
Software Configuration
- Operating System - Windows XP/7
- Programming Language - Java
- Database - MySQL
- Tool - Netbeans

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4.2 Results of Practical Work
Performance comparison between individual auditing and batch auditing.
V. CONCLUSION
This paper presents a comprehensive study for improvement of user navigation through
website structure using CURE algorithm. We use this algorithm to improve the navigation
effectiveness of a website while minimizing changes to its current structure. The tests on a real
websites dataset showed that CURE algorithm could provide significant improvements to user
navigation by adding only few new links. Optimal solutions were quickly obtained, suggesting that the
CURE algorithm is very effective to real world websites datasets.
REFERENCES
[1] M.A.Shah, R.Swaminathan, M. Baker (2008), Privacy preserving audit and extraction of
digital contents, Cryptology ePrint Archive.
[2] Cong Wang, QianWang, KuiRen, Wenjing Lou (2009),Ensuring Data Storage Security in
Cloud Computing.
[3] G. Ateniese, R.D. Pietro, L.V. Mancini, and G. Tsudik, “Scalable and Efficient Provable Data
Possession,” Proc. Fourth Int’l Conf. Security and Privacy in Comm. Networks (Secure Comm
’08), pp. 1-10,2008.
[4] C. Erway, A. Kupcu, C. Papamanthou, and R. Tamassia, “Dynamic Provable Data
Possession,” Proc. 16th ACM Conf. Computer and Comm. Security (CCS ’09), 2009.
[5] K.D. Bowers, A. Juels, and A. Oprea, “Hail: A High-Availability and Integrity Layer for Cloud
Storage,” Proc. 16th ACM Conf. Computer and Comm. Security (CCS ’09), pp. 187-198,
2009.
[6] A. Konwinski, G. Lee, D. A. Patterson, A. Rabkin, I. Stoica, M. Zaharia, “Above the clouds: A
berkeley view of cloud computing,” University of California, Berkeley, Tech. Rep, 2009.
[7] Cong Wang, QianWang, KuiRen, Wenjing Lou (2010),Privacy Preserving Public Auditing
for Data Storage Security in Cloud Computing.
[8] A. L. Ferrara, M. Greeny, S. Hohenberger, M. Pedersen (2009), Practical short signature batch
verification, in Proceedings of CT-RSA, volume 5473 of LNCS. Springer-Verlag,
pp. 309–324.

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