Aj04602248254

S. B. Dash et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 6( Version 1), June 2014, pp.248-254
www.ijera.com 248 | P a g e
A Theoretical Aspect of Cloud Computing Service Models and Its
Security Issues: A Paradigm
S. B. Dash*, H.Saini **, T.C.Panda*, A. Mishra***
* Department of Information Technology, Orissa Engineering College, Bhubaneswar, India-752050
** Department of Computer Science & Engineering, Jaypee University of Information Technology, Solan,
India-173234
***Department of Mathematics, CUTM, Paralakhemundi, India-761211
ABSTRACT
Cloud computing is a distributed computing environment that provides on demand services to the users for
deploying their computational needs in a virtualized environment without the knowledge of technical
infrastructure. Due to reliability, scalability, high performance and low band width most of the organizations are
running their applications in cloud. The cloud service providers provide the services to the registered cloud users
on payment basic across the glove. The cloud services are basically categorized as SaaS, PaaS, and IaaS. The
services are available to the users depending on cloud deployment and the SLA (service level agreements)
between the service providers and the users. Providing security to the users and trust into cloud environment is
the responsibility of the cloud service providers. The main objective of this paper is to provide a clear idea about
the cloud service models and outline the security issues in the service models.
Keywords - Cloud computing; Cloud computing models; Cloud Security Issues; Cloud Security Threats.
I. INTRODUCTION
Cloud computing is one of the most significantly
achieved development in the IT industry. Most of the
companies are running their applications in the cloud
due to the rapid advancement in communication
network. It is a next generation computing platform
that helps the users to share the resources through
communication mediums. According to National
Institute of Standards and Technology (NIST) one of
the most accepted definition of cloud computing is
“Cloud computing is a model for enabling
ubiquitous, convenient, on-demand network access to
a shared pool of configurable computing resources
(e.g., networks, servers, storage, applications, and
services) that can be rapidly provisioned and
released with minimal management effort or service
provider interaction”. European Community for
Software and Software Services (ECSS) defines
“cloud computing as the delivery of computational
resources from a location other than your current
one”.[1,2,3] So in simple words cloud computing can
be defined as a distributed computing environment
that enables the users to access and exchange their
resources (applications and data) remotely and
provides services to use the remote hardware and
software within a network without the knowledge of
technological infrastructure[4] . The figure-1 shown
below gives a clear idea regarding the infrastructure
requirements for cloud deployment.
Figure-1The Cloud infrastructure
II. ADVANTAGES OF CLOUD
COMPUTING
1. Flexibility/Elasticity:
Users can access computing resources as and
when needed, without any human interaction.
Capabilities can be rapidly and elastically provided in
some cases automatically.[5]
2. Scalability Of Infrastructure.
New nodes can be added or removed from the
network as can physical servers, with limited
modifications to infrastructure set up and software.
Cloud architecture can scale horizontally or vertically
according to the user‟s requirements.[5]
RESEARCH ARTICLE OPEN ACCESS

3. Broad Network Access.
Capabilities are available over the network and
accessed through standard mechanisms that promotes
by using heterogeneous platforms (like mobile
phones, laptops, and PDAs).
4. Location Independence.
Cloud interfaces are location independent and
they can be accessed by well established interfaces
such as Web services and Web browsers, so that no
knowledge about exact location of the user is
required. It gives high level of abstraction to the
users data.
5. Unlimited Storage.
Storing information in the cloud gives almost
unlimited storage capacity. Hence no more need to
worry about running out of storage space or
increasing current storage space availability.
6. Easy Access to Information.
Once registered in the cloud environment any
one can access the information from any location
provided, there is an Internet connection.
7. Economies Of Scale And Cost Effectiveness.
Cloud implementations regardless of the
deployment models tend to be as large as possible in
order to take advantage of economies of scale. Large
cloud deployments can often be located close to
cheap deployment to lower cost. It does not require
upfront investment and much capital expenditure.
Users may pay and use or pay for services and
capacity as they need them.
8. Backup and Recovery.
Since all the user‟s data is stored in the cloud,
backing it up and restoring the same is relatively
much easier than storing the same on a physical
device. Most cloud service providers are usually
competent enough to handle recovery of information.
Hence this makes the entire process of backup and
recovery much simpler than other traditional methods
of data storage.
9. Reliability
It improves the use of multiple sites which
makes cloud computing suitable for business
continuity and disaster recovery.
10. Sustainability
It improves resource utilization and makes the
cloud environment more efficient.
III. CLOUD COMPUTING MODELS
Based on the usages of data and applications
cloud computing services are broadly classified in
three different types called as cloud service models.
Figure- 2 shows the different types of cloud service
model present in cloud environment.
Figure-2 Types of cloud service models
And according to the usages of data and applications
required by the users the cloud computing models are
broadly classified in four different types called as
cloud deployment models.[6,7,8,9].
IV. CLOUD COMPUTING SERVICE
MODELS.
A. Infrastructure as a Service(IaaS)
Infrastructure as a Service (IaaS) is one of
the three fundamental service models of cloud
computing . A layers of cloud computing model and
their infrastructural requirements is shown in the
figure -3. In this model the users are allocated with
computing resources in order to run their
applications. The computing services are provided in
a virtualized environment i.e in cloud by using a
communication network. The best known example of
IaaS is Amazon Cloud Formation, Amazon EC2. It
can be implemented by utilizing the concepts like
Enterprise infrastructure, Cloud hosting, and Virtual
Data Centers (VDC). Network as a service (NaaS) is
a category of cloud infrastructure services where the
user can use the network connectivity as a services.
NaaS involves the optimization of resource
allocations and resource computing in the network.
VPN, and bandwidth on demand are the common
example of NaaS.[10,11,12,13,14]
Advantages of IaaS.
1. Resources are available on demand as and when
the user requires it. That means the user will not
have to worry about the Infrastructure required to
run the application. so this scalable.
2. In IaaS the Infrastructure i.e the virtualized
environment is set up and maintained by the
cloud provider. So no investment in hardware for

the users. As it saves the implementation cost
and time of execution.
3. The service can be accessed on demand and the
client only pays for the resource or application
used not for the Infrastructure
4. The service can be accessed from any location
24X7 provided there is an internet connection.
So IaaS is location independent.
5. Physical security of user‟s data is the
responsibility of the cloud provider. So the time
required to give security to data is saved.
6. The chance of system failure is less. Any case of
failure will be smoothly handled by the service
provider. So it is fault tolerant.
Figure-3 The layers of cloud service models
B. Platform as a Service(PaaS).
Platform as a Service is a category of cloud
computing service model that provides the
developers a platform to build and use applications
and services by using a communication network.
PaaS services are available in the cloud and accessed
by users by using web browsers. In the PaaS model,
cloud providers provides a platform which includes
operating system, programming language execution
environment, database, and web server. The users can
use these facilities to develop their applications. The
well known PaaS providers are AWS Elastic
Beanstalk, Cloud Foundry, Heroku, Force.com,
OrangeScape. The services are constantly updated by
the service providers, with existing features upgraded
and additional features added. In PaaS services the
user has to pay for a subscription basis and charged
just for what they use. PaaS includes Operating
system, Server-side scripting environment, Database
management system, Server Software, Network
access tools for design and development and web
hosting. [13,14,15,16]
Advantages of PaaS:
1. The user doesn‟t have to invest for physical
infrastructure as it will be provided by IaaS on
demand. So this gives fully mobility to focus on
the development of applications.
2. With PaaS services application development is
simple. So anyone can develop an application
with less technical knowledge by using web
browser.
3. User can have control over the applications that
are installed within their platforms and can create
a platform that suits their specific requirements.
They can „pick and choose‟ the features they feel
as necessary.
4. In PaaS the applications can be changed or
modified if required.
5. The services are not isolated, application specific
or location dependent. So users in various
locations can work together provided they are
connected through a communication medium.
6. Security of user‟s data and the application is the
responsibility of the cloud provider. Data
security, backup and recovery are the major
security issues.
C. Software as a Service(SaaS)
The third model is Software as a Service which
provides a platform in which the users access the
software from the cloud. The users of SaaS will not
have to worried about managing the cloud
infrastructure and platform on which the application
is running. The software installation and operation is
the responsibility of the service providers and already
available by using IaaS and PaaS.[13,14,15,16] This
is typically end user applications delivered on
demand over a network on a pay per use basis. The
examples of SaaS include: google apps,
MicrosoftOffice365, Onlive, GT Nexus, Marketo,
and TradeCard. These applications are hosted in “the
cloud” and can be used for a wide range of tasks for
both individuals and organizations.[17,18,19]
Advantages of SaaS.
1. No additional infrastructure or platform required
to run the applications, as it provided by the
service provider (IaaS and PaaS).
2. Software Applications are ready to use once the
user subscribes. The user only have to pay for
software not for infrastructure or platform setup.
3. With SaaS services application development is
simple. So anyone can develop an application
with less technical knowledge any time by using
web browser.
4. Software updating is automatic i.e if any updates
are available online to existing user, offered free
of charges.
5. SaaS provides mobility to the user where
applications can be accessed via any internet
enabled device, which makes it ideal for those
who use a number of different devices, such as

internet enabled phones and tablets, and those
who don‟t always use the same computer.
6. The services are not isolated, application specific
or location dependent. So users in various
locations can work together provided they as
connected through a communication medium.
7. There are no initial setup costs is required with
SaaS, as SaaS offered with other services.
V. SECURITY ISSUES
The security issues in cloud computing
environment are greatest challenge of information
system. Understanding the risks of the security and
privacy in the cloud computing environment and
developing efficient and effective solutions for it is
really a difficult task. Confidentiality, integrity,
reliability and availability are widely used
terminology for security issues in cloud computing
environment means that the user‟s data in the cloud
should remain confidential and protected from
unauthorized access.[19]So the implementation of the
cloud computing architecture must be ensured about
the security of its resource nodes. Some of the
security issues occur in cloud computing are listed
below.[20,21,22,23,24]
1. Cloud Security
This includes organizational and technical issues
related to keeping cloud services at an acceptable
level of security by ensuring the computing resources
available and usable by its authentic users. Security
threats to cloud infrastructure would affect multiple
users even if only one site is attacked.[20]These risks
can be overcome by using encrypted file systems,
security applications, data loss software and buying
security hardware.
2. Privacy in Cloud.
Privacy is the process of making sure that the
user‟s data remains private, confidential and
restricted from unauthorized users. Due to data
virtualization the users data may be stored in various
virtual data centers rather than in the local computers.
So the unauthorized users may access the private
information of the authorized users. Data
authentication is one of the most popular options of
security before putting the sensitive data into
cloud.[20]
3. Data integrity and Reliability
In cloud computing, anyone from any location
can access the data. Cloud does not differentiate
between common data and sensitive data. So an
important aspect of cloud services is availability of
user‟s data with reliability. It is necessary for the
cloud service provider to ensure the integrity by
making their system capable to check over the cloud
data from any unauthorized access.
4. Performance and Bandwidth cost.
The major issues that can affect performance in
cloud based environment is due to the unethical
transaction-oriented and data access applications. So
the users who are at a long distance from cloud
providers may experience high latency and delay, this
is due to the availability bandwidth in the network.
Bandwidth cost may be low for smaller Internet-
based applications, which are not data intensive, but
could significantly, grow for data-intensive
applications. The service providers instead of saving
money on hardware, they should spend more for the
bandwidth. This can deliver intensive and complex
application over the network.
VI. SECURITY THREATS
A threat is define as an external force by which
the nodes existing in one state transfers into other. A
node in the cloud environment stores the data and
information and gives the user a platform to use the
application in the form of services. There are
significant numbers of attacks or intrusions occurs in
the cloud based applications. Some well known
attacks are listed below.[25-32]
1. SQL Injection Attack.
An SQL injection is a computer attack mostly
affects to SAAS model, in which malicious code is
embedded with a poorly-designed application,
executes unauthorized SQL commands by taking
advantage of insecure interface connected through
Internet.[19] SQL injection attacks are used to access
information from databases, which is protected from
public access.SQL injection attacks are avoided by
ensuring systems having strong input validation.
2. Abuse And Nefarious Use Of Cloud
Computing
In this threat the hackers take the advantages of
shortcomings in the authentic registration process
associated with cloud. After the successful
registration, the cloud service providers offer SAAS,
IAAS and PAAS services to the users. But hackers
may be able to conduct susceptible activities like
Spamming and Phishing. This threat exists in all the
three layers of the service models.
3. Net Sniffers
Net sniffer is a type SAAS service model threat
in which the attackers use to gain access through
applications, which can capture packets flowing in a
network and if the data that is being transferred
through these packets is not encrypted. Then data can
be publicly available and read by any one.
4. Session Hijacking
Session hijacking is a security attack on a user
session over a protected network. when a user logs

into a website, a session is created on that Web
Server for that user, this session contains all this
user's information being used by the server so the
username and password is not required at every page
request. So hackers having adequate knowledge can
exploits a valid computer session and gains access to
a user‟s session identifiers through HTTP. The Web
server uses a unique identifier (Session Identifier) to
authenticate the users for the session. The hackers by
using Session Hijacking attack unethically gets the
user's session identifier and then gain the illegal
access to the user data. the most common Session
hijacking attacks are Session Prediction ,Session
Sidejacking ,Session Fixation ,Cross Site Scripting
and available in SAAS and PAAS.
5. Man In The Middle Attack
Another type of session hijacking is known as a
man-in-the-middle attack. Where the attacker uses
a sniffer to observe the communication between
devices and collect the data that is transmitted. In this
the attackers make independent connections with the
victim‟s computer and making them believe that they
are connected directly to each other over a private
connection. But in fact the entire session is controlled
by the attackers. This is a threat to SAAS.
6. Denial Of Services
A Denial Of Services is a attack in the SAAS
layer, that attempts to make the network resource and
services actually assigned to the authorized users
virtually unavailable. As it acts as an interrupt or
suspend of services for authorized users temporarily
or indefinitely.
7. Flooding Attacks
Flooding is a Denial of Service attack that is
designed to increase network conjunctions by
flooding it with huge amount of traffic. Flooding
attacks occur when a network or service becomes so
weighed with packets contains data. It attacks
a server or host with connections that cannot be
completed and finally fills the host memory buffer
with unused and redundant data. Once the buffer is
full no further connections can be made. So the result
is a Denial of Service. It is available in PAAS and
IAAS layer of cloud service model.
8. Privacy Breach
Since data from various users and business
organizations available together in a cloud
environment, so breaching in cloud environment will
attack the data of the authorized users. Hence the
unauthorized users can access the private data of the
cloud users and do some susceptible activities with
the data. This will affect mostly the SAAS users. A
list of security threats that occur in cloud service
models are given in the Table-1.[28-36]
Table-1: Security threat in various cloud service
model
.
VII. CONCLUSION AND FUTURE
WORK
Understanding the risks of the security and
privacy in the cloud computing environment and
developing efficient and effective solutions for it is
really a difficult task. Confidentiality, integrity,
reliability and availability are widely used
terminology for security issues in cloud computing
environment. In this paper, we have discussed some
trust issues and classify the security threats related to
SECURITY THREATS IN SERVICE MODELS
SLNO SECURITY
THREATS
SAAS PAAS IAAS
1. Abuse And
Nefarious Use
Of Cloud
Computing
√ √ √
2. Data And
Information Loss
x x √
3. Denial Of
Services
√ x x
4. Exposure In
Network
√ x x
5. Hardware
Attack.
x x √
6. Insecure
Interfaces And
APIs
√ √ √
7. Malicious
Insiders
√ √ √
8. Man In The
Middle Attack
√ x x
9. Modification
And Deletion Of
Data.
√ √ x
10. Modification
And Threat To
Hardware
x x √
11. Net Sniffers √ x x
12. Port Scanning x x √
13. Privacy Breach √ x x
14. Session
Hijacking
√ √ x
15. Shared
Technology
Vulnerabilities.
x √ √
16. SQL Injection
Attack.
√ x x
17. Unauthorized
And Unauthentic
Use Of Cloud
√ x x
18. Unknown Risk
Profile.
√ √ √

cloud computing service models. As security is the
biggest issue, so these issues have to be solved as
soon as possible to make maximum benefits of the
cloud usages. These threats can be predicted from the
attack history or from the vulnerability analysis of the
network which requires a considerable efforts and use
of resources. Therefore, a prediction method can help
to fix these issues.
REFERENCES
[1]. Wikipedia, http://en.wikipedia.org/wiki
/Cloud_Computning
[2]. Rafael Moreno-Vozmediano,Rubén S.
Montero, Ignacio M. Llorente,” Key
Challenges in Cloud Computing -Enabling
the Future Internet of Services”, Published
by the IEEE Computer Society 1089-
7801/13/ © 2013 IEEE, IEEE internet
computing
[3]. Dimitrios Zissis , Dimitrios Lekkas,
“Addressing cloud computing security
issues”, 0167-739X/ © 2010 Elsevier B.V.
All rights
reserved.doi:10.1016/j.future.2010.12.006.
[4]. M.Rajendra Prasad, R. Lakshman Naik,
V.Bapuji,” Cloud Computing : Research
Issues and Implications ”, International
Journal of Cloud Computing and Services
Science (IJ-CLOSER) Vol.2, No.2, April
2013, pp. 134~140 ISSN: 2089-3337.
[5]. Francesco M.A and Gianni F. “An approach
to a cloud Computing network”, IEEE,
August 2008, pp113-118
[6]. Huaglory Tianfield,”Cloud Computing
Architectures”, 978-1-4577-0653-
0/11/©2011 IEEE.
[7]. Xu Xiaoping, Yan Junhu,” Research on
Cloud Computing Security Platform”, 978-
0-7695-4789-3/12 © 2012 IEEE DOI
10.1109/ICCIS.2012.238.
[8]. “Understanding Cloud Computing
Vulnerabilities”, by the ieee computer and
reliability societies 1540-7993/11/ © 2011
IEEE march/april 2011.
[9]. Hassan Takabi , James B.D. Joshi, Gail-Joon
Ahn, “Security and Privacy Challenges in
Cloud Computing Environments”, by the
ieee computer and reliability societies ,1540-
7993/10/ © 2010 IEEE ,
november/december 2010.
[10]. Zhifeng Xiao and Yang Xiao, Senior
Member, IEEE,” Security and Privacy in
Cloud Computing”, IEEE communications
surveys & tutorials, VOL. 15, NO. 2, second
quarter 2013, 1553-877X/13/ c_ 2013 IEEE.
[11]. Peter Mell,” What‟s Special about Cloud
Security? ”, IT Pro July/August 2012, P u b l
i s h e d by t h e I E E E Comp u t e r S o c i
e t y, 1520-9202/12/ © 2012 IEEE.
[12]. Jianhua Che, Yamin Duan, Tao Zhang, Jie
Fan,” Study on the security models and
strategies of cloud computing”, 1877-7058
© 2011 Published by Elsevier Ltd.
doi:10.1016/j.proeng.2011.11.2551.
[13]. Xue Jing, Zhang Jian-jun2. “A Brief Survey
on the Security Model of Cloud Computing"
978-0-7695-4110-5/10 © 2010 IEEE DOI
10.1109/DCABES.2010.103
[14]. Engr: Farhan Bashir Shaikh, Sajjad
Haider,” Security Threats in Cloud
Computing”, 978-1-908320-00-1/11@2011
IEEE
[15]. H.Sato,et al., “A Cloud Trust Model in a
Security Aware Cloud”, SAINT2010,
pp.121-124.
[16]. Mladen A. Vouch, ”Cloud Computing
Issues, Research and Implementations‖”,
Journal of Computing and Information
Technology - CIT 16, 2008, 4, 235–246
[17]. Latifa Ben, Arfa Rabai , Mouna Jouini, Anis
Ben Aissa , Ali Mili,” A cybersecurity
model in cloud computing environments”,
1319-1578 ª 2012 King Saud University.
Production and hosting by Elsevier B.V. All
rights
reserved.http://dx.doi.org/10.1016/j.jksuci.2
012.06.002.
[18]. M. Mackay, T. Baker, A. Al-Yasiri,”
Security-oriented cloud computing platform
for critical infrastructures”, 0267-3649/
2012 M. Mackay, T. Baker & A. Al-Yasiri.
Published by Elsevier Ltd. All right
reserved.http://dx.doi.org/10.1016/j.clsr.201
2.07.007.
[19]. S. Subashini , V.Kavitha,” A survey on
security issues in service delivery models of
cloud computing”, 1084-8045/ 2010
ElsevierLtd. All rights reserved.
doi:10.1016/j.jnca.2010.07.006.
[20]. Xue Jing, Zhang Jian-jun,” A Brief Survey
on the Security Model of Cloud
Computing”, 2010 Ninth International
Symposium on Distributed Computing and
Applications to Business, Engineering and
Science, 978-0-7695-4110-5/10 © 2010
IEEE DOI 10.1109/DCABES.2010.103.
[21]. Shigeaki Tanimoto, Manami Hiramoto,
Motoi Iwashita, Hiroyuki Sato, Atsushi
Kanai” Risk Management on the Security
Problem in Cloud Computing ”, 2011 First
ACIS/JNU International Conference on
Computers, Networks, Systems, and
Industrial Engineering, 978-0-7695-4417-
5/11 © 2011 IEEE DOI
10.1109/CNSI.2011.82.

[22]. Farhan Bashir Shaikh, Sajjad Haider,”
Security Threats in Cloud Computing”, 978-
1-908320-00-1/11 © 2011 IEEE.
[23]. Wentao Liu,” Research on Cloud
Computing Security Problem and Strategy”,
978-1-4577-1415-3/12/©2012 IEEE.
[24]. Eman M.Mohamed, Hatem S. Abdelkader,
Sherif EI-Etriby,” Enhanced Data Security
Model for Cloud Computing ”, The 8th
International Conference on INFOrmatics
and Systems (INFOS2012) - 14-16 May
2012, Cloud and Mobile Computing Track,
Faculty of Computers and Information -
Cairo University.
[25]. Gurudatt Kulkarni , Jayant Gambhir
,Tejswini Patil ,Amruta Dongare,” A
Security Aspects in Cloud Computing ”,
978-1-4673-2008-5/12/ ©2012 IEEE.
[26]. Su Qinggang, Wang Fu, Hang Qiangwei,”
Study of Cloud Computing Security Service
Model”, 978-1-4577-1964-6/12/ ©2012
IEEE.
[27]. Anup Sharma, Robin A. Gandhi, William
Mahoney, William Sousan, Qiuming Zhu,”
Building a Social Dimensional Threat
Model from Current and Historic Events of
Cyber Attacks”, IEEE International
Conference on Social Computing / IEEE
International Conference on Privacy,
Security, Risk and Trust, 978-0-7695-4211-
9/10 © 2010 IEEE DOI
10.1109/SocialCom.2010.145.
[28]. Devki Gaurav Pal, Ravi Krishna, Prashant
Srivastava, Sushil Kumar, Monark Bag,
Vrijendra Singh,” A Novel Open Security
Framework for Cloud Computing ”,
International Journal of Cloud Computing
and Services Science (IJ-CLOSER) Vol.1,
No.2, June 2012, pp. 45~52 ISSN: 2089-
3337.
[29]. Y. Jianfeng, C. Zhibin. "Cloud Computing
Research and Security Issues" CISE 2010.
Dec, 2010
[30]. Ashish Kumar,” World of Cloud Computing
& Security ”, International Journal of Cloud
Computing and Services Science (IJ-
CLOSER) Vol.1, No.2, June 2012, pp.
53~58 ISSN: 2089-3337.
[31]. Wenjuan FAN, Shanlin Yang, Jun Pei, He
Luo,” Building trust into cloud ”,
International Journal of Cloud Computing
and Services Science (IJ-CLOSER) Vol.1,
No.3, August 2012, pp. 115~122 ISSN:
2089-3337.
[32]. Hemraj Saini, Dinesh Saini. Malicious
Object dynamics in the presence of Anti
Malicious Software" European Journal of
Scientific Research, [ISSN: 1450-216X],
volume-18, Issue-3, pp.-491-499, (2007).
[33]. Zhidong Shen, Qiang Tong,” The Security
of Cloud Computing System enabled by
Trusted Computing Technology ”, 2010 2nd
International Conference on Signal
Processing Systems (ICSPS), 978-1-4244-
6893-5/C 2010 IEEE
[34]. Sylvain P. Leblanc, Andrew Partington, Ian
Chapman, and Mélanie Bernier. An
overview of cyber attack and computer
network operations simulation. In
Proceedings of the 2011 Military Modeling
& Simulation Symposium (MMS '11)
(2011). Society for Computer Simulation
International, San Diego, CA, USA, 92-100.
[35]. Hemraj Saini, T. C. Panda, Minaketan
Panda. 2011. Prediction of Malicious
Objects in Computer Network and Defense”,
International Journal of Network Security &
Its Applications (IJNSA), Vol.3, No.6, pp.-
161-171, 2011.
[36]. Xiaojun Yu, Qiaoyan Wen,” A view about
cloud data security From data life cycle”,
978-1-4244-5392-4/10/ ©2010 IEEE

Aj04602248254

More Related Content

Aj04602248254