This work discusses the security of data in cloud computing. It is a study of data in the cloud and aspects related to it concerning security. The work will go in to details of data protection methods and approaches used throughout the world to ensure maximum data protection by reducing risks and threats. Availability of data in the cloud is beneficial for many applications but it poses risks by exposing data to applications which might already have security loopholes in them. Similarly, use of virtualization for cloud computing might risk data when a guest OS is run over a hypervisor without knowing the reliability of the guest OS which might have a security loophole in it. This task will also provide an insight on data security aspects for Data-in-Transit and Data-at-Rest. The study is based on all the levels of SaaS (Software as a Service), PaaS (Platform as a Service) and IaaS (Infrastructure as a Service). Growth of cloud computing is mainly hampered due to these security concerns and challenges. Proper security arrangements are need to be placed before selecting the service provider for any cloud computing service and customers need to be very careful about understanding the risks of security breaches and challenges of using this new computing environment. The methodology implements on Cloud Sim 3.0.1 toolbox, which is configure in Net Beans 8.1. The outcome demonstrates that it gives improved execution contrasted with supplementary predictable security algorithm. Crypto operation time, key operation time and total execution are reduced by 2.72%, 7.91% and 4.63% significantly.