Cloud computing is one of the most significant milestones in recent times in the history of computers. In the last few years, cloud computing has grown from being a promising business concept to one of the fastest growing segments of the IT industry. The basic concept of cloud computing is to provide a platform for sharing of resources which includes software and infrastructure with the help of virtualization. In order to provide quality of service, this environment makes every effort to be dynamic and reliable. As in most other streams of computers, security is a major obstacle for cloud computing.