In this paper an efficient security mechanism has been adopted for the cloud computing environment. It also provides an extendibility of cloud computing environment with big data and Internet of Things. AES-256 and RC6 with two round key generation have been applied for data and application security. Three-way security mechanism has been adopted and implemented. It is user to user (U to U) for data sharing and inter cloud communication. Then user to cloud (U to C) for data security management for application level hierarchy of cloud. Finally, cloud to user (C to U) for the cloud data protection. The security analysis has been tested with different iterations and rounds and it is found to be satisfactory.