06-09-2012, 03:46 PM
Cloud Computing Security: From Single to Multi-Clouds
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Abstract
The use of cloud computing has increased rapidly
in many organizations. Cloud computing provides
many benefits in terms of low cost and accessibility of
data. Ensuring the security of cloud computing is a
major factor in the cloud computing environment, as
users often store sensitive information with cloud
storage providers but these providers may be
untrusted. Dealing with “single cloud” providers is
predicted to become less popular with customers due
to risks of service availability failure and the
possibility of malicious insiders in the single cloud. A
movement towards “multi-clouds”, or in other words,
“interclouds” or “cloud-of-clouds” has emerged
recently.
Introduction
The use of cloud computing has increased rapidly in
many organizations. Subashini and Kavitha [49] argue
that small and medium companies use cloud computing
services for various reasons, including because these
services provide fast access to their applications and
reduce their infrastructure costs.
Cloud providers should address privacy and
security issues as a matter of high and urgent priority.
Dealing with “single cloud” providers is becoming
less popular with customers due to potential problems
such as service availability failure and the possibility
that there are malicious insiders in the single cloud. In
recent years, there has been a move towards “multiclouds”,
“intercloud” or “cloud-of-clouds”.
Background
NIST [1] describes cloud computing as “a model for
enabling 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”.
Cloud Computing Components
The cloud computing model consists of five
characteristics, three delivery models, and four
deployment models [1]. The five key characteristics of
cloud computing are: location-independent resource
pooling, on-demand self-service, rapid elasticity, broad
network access, and measured service [51]. These five
characteristics represent the first layer in the cloud
environment architecture (see Figure1).
Cloud Service Providers Examples
In the commercial world, various computing needs
are provided as a service. The service providers take
care of the customer's needs by, for example,
maintaining software or purchasing expensive
hardware. For instance, the service EC2, created by
Amazon, provides customers with scalable servers. As
another example, under the CLuE program, NSF joined
with Google and IBM to offer academic institutions
access to a large-scale distributed infrastructure [4].
There are many features of cloud computing. First,
cloud storages, such as Amazon S3, Microsoft
SkyDrive, or NirvanixCLoudNAS, permit consumers
to access online data. Second, it provides computation
resources for users such as Amazon EC2. Third,
Google Apps or versioning repositories for source code
are examples of online collaboration tools [12].
Cloud service providers should ensure the security
of their customers’ data and should be responsible if
any security risk affects their customers’ service
infrastructure. A cloud provider offers many services
that can benefit its customers, such as fast access to
their data from any location, scalability, pay-for-use,
data storage, data recovery, protection against hackers,
on-demand security controls, and use of the network
and infrastructure facilities [49].
Security Risks in Cloud Computing
Although cloud service providers can offer benefits
to users, security risks play a major role in the cloud
computing environment [53]. Users of online data
sharing or network facilities are aware of the potential
loss of privacy [12]. According to a recent IDC survey
[16], the top challenge for 74% of CIOs in relation to
cloud computing is security. Protecting private and
important information such as credit card details or
patients’ medical records from attackers or malicious
insiders is of critical importance [34]. Moving
databases to a large data centre involves many security
challenges [55] such as virtualization vulnerability,
accessibility vulnerability, privacy and control issues
related to data accessed from a third party, integrity,
confidentiality, and data loss or theft. Subashini and
Kavitha [49] present some fundamental security
challenges, which are data storage security, application
security, data transmission security, and security
related to third-party resources.