INTRODUCTION
Cloud computing refers to the delivery of computing and storage capacity (Gruman ,2008) as a service to a heterogeneous community of end-recipients. The name comes from the use of clouds as an abstraction for the complex infrastructure it contains in system diagrams (Gruman, 2008). Cloud computing entrusts services with a user's data, software and computation over a network. Cloud computing can be public or private or hybrid. In public cloud, applications, storage, and other resources are made available to the general public by a service provider. These services are free or offered on a pay-per-use model. Generally, public cloud service providers like Amazon AWS, Microsoft and Google own and operate the infrastructure and offer access only via Internet (direct connectivity is not offered).Private cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third-party and hosted internally or externally (Ryan, 2011). Undertaking a private cloud project requires a significant level and degree of engagement to virtualize the business environment, and it will require the organization to reevaluate decisions about existing resources. When it is done right, it can have a positive impact on a business, but every one of the steps in the project raises security issues that must be addressed in order to avoid serious vulnerabilities. While Hybrid cloud is a composition of two or more clouds (private, community or public) that remain unique entities but are bound together, offering the benefits of multiple deployment models (Ryan, 2011). As cloud computing is achieving increased popularity, also is the security security issues increasing.
1.1 Background of study
In just a few years, cloud computing platforms and services have dramatically changed the landscape of software application development. (Voorsluys, etal 2011) The emergence of the Cloud system has simplified the deployment of large-scale