Although cloud computing can help companies accomplish more by breaking the physical bonds between an IT infrastructure and its users, heightened security threats must be overcome in order to benefit fully from this new computing paradigm that offers an innovative business model for organizations to adopt IT without upfront investment. Despite the potential gains achieved from the cloud computing, the model security is still questionable which impacts the cloud model adoption. The security problem becomes more complicated under the cloud model as new dimensions have entered into the problem scope related to the model architecture, multi-tenancy, elasticity, and layers dependency stack.
Cloud Computing is a jargon, in other words a new computing model, in which the public Internet is used to connect to provider’s hosted network, infrastructure, platform and/or applications to leverage reliable services. Cloud has left all other distributed computing structures/mechanisms far behind both in competition and in terms of popularity and success.
The primary reason is that, any service can be scaled up or down as and when required, based on customer’s needs. Cloud offers flexibility, quick to production model, and offers capital reduction by enabling organizations to port all their data, information and infrastructure to off-site provider hosted premises.
Cloud Computing is essentially a combination of existing technologies that are succeeding in make a paradigm shift in building and maintaining distributed computing systems making use of, multiprocessor, virtualization technology, network based distributed data storage and networking. The cloud providers have Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) and many more services to offer.
2. Cloud Computing Security Problems
The cloud system is running in the internet and the security problems in the internet also can be found in the cloud system. The cloud system is not different the traditional system in the PC and it can meet other special and new security problems.
The biggest concerns about cloud computing are security and privacy. The traditional security problems such as security vulnerabilities, virus and hack attack can also make threats to the cloud system and can lead more serious results because of property of cloud computing. Hackers and malicious intruder may hack into cloud accounts and steal sensitive data stored in cloud systems. The data and business application are stored in the cloud center and the cloud system must protect the resource carefully.
Cloud computing is a technology evolution of the widespread adoption of virtualization, service oriented architecture and utility computing. over the Internet and it includes the applications, platform and services. If the systems meet the failure, fast recovery of the resource also is a problem. The cloud systems hide the details of service implementation technology and the management. The user can’t control the progress of deal with the data and the user can’t make sure the data security by themselves. The data resource storage and operation and network transform also deals with the cloud system. The key data resource and privacy data are very import for the user.
The cloud must provide data control system for the user. The data security audit also can be deployed in the cloud system. Data moving to any authorized place you need it, in a form that any authorized application can use it, by any authorized user, on any authorized device. Data integrity requires that only authorized users can change the data and confidentiality means that only authorized users can read data. Cloud computing should provide strong user access control to strengthen the licensing, certification, quarantine and other aspects of data management.
In the cloud computing, the cloud provider system has many users in a dynamic response to changing service needs. The users do not know what position the data and do not know which servers are processing the data. The user do not know what network are transmitting the data because the flexibility and scalability of cloud system. The user can’t make sure data privacy operated by the cloud in a confidential way. The cloud system can deploy the cloud center in different area and the data can be stored in different cloud node. The different area has different law so the security management can meet the law risk. Cloud computing service must be improved in legal protection.
3. Cloud Computing Approaches
To achieve efficient utilization of resources, cloud providers need to increase their resource utilization while decreasing cost. At the same time consumers need to use resources as far as needed while being able to increase or decrease resources consumption based on actual demands. The cloud computing model meets such needs via a win-win solution by delivering two key characteristics: mulit-tenancy and elasticity. Both characteristics tum out to have serious implications on the cloud model security.
Multi-tenancy implies sharing of computational resources, storage, services, and applications with other tenants. This sharing of resources violates the confidentiality of tenants’ IT assets which leads to the need for secure multi- tenancy. To deliver secure multitenancy there should be isolation among tenants’ data and location transparency where tenants have no knowledge or control over the specific location of their resources, to avoid planned attacks that attempt to co-locate with the victim assets. In IaaS, isolation should consider VMs’ storage, processing, memory, cache memories, and networks. In PaaS, isolation should cover isolatation among running services and APIs’ calls. In SaaS isolation should isolate among transactions carried out on the same instance by different tenants and tenants’ data.
Elasticity implies being able to scale up or down resources assigned to services based on the current demand. Scaling up and down of tenant’s resources gives the opportunity to other tenants to use the tenant previously assigned resources. This may lead to confidentiality issues.
For example, tenant A scaled down so it releases resources, these resources are now assigned to tenant B who in turn use it to deduce the previous contents of tenant A. Moreover, Elasticity includes a service placement engine that maintains a list of the available resources from the provider’s offered resources pool. This list is used to allocate resources to services. Such placement engines should incorporate cloud consumers’ security and legal requirements such as avoid placing competitors services on the same server, data location should be within the tenants’ country boundaries Placement engines may include a migration strategy where services are migrated from physical host to another or from cloud to another in order to meet demands and efficient utilization of the resources. This migration strategy should take into account the same security constraints. Furthermore, security requirements defined by service consumers should be migrated with the service and initiates a process to enforce security requirements on the new environment, as defmed by cloud consumers, and updates the current cloud security model.
Cloud computing has a very fast pace of development and shows good prospects and great potential. The cloud computing is related to many areas of information management and services. The data security issue becomes more prominent than the traditional network because the data in the cloud computing environment is greatly dependent on the network and server.
 Akhil Behl, Emerging Security Challenges in Cloud Computing, 2011 World Congress on Information and Communication Technologies, 2011
 Anas BOUA Y AD, Asmae BLILA T, Nour el houda MEJHED, Mohammed EL GHAZI, Cloud computing : security challenges, IEEE, 2012
 Wentao Liu, Research on Cloud Computing Security Problem and Strategy, IEEE, 2012