Today life can’t begin internet and all the general purpose applications are available from website, out of these applications mostly applications are uses cloud computing technology. So cloud computing technology will become one of the new prototypes for the internet based application. It has huge environment and open distributed system. Cloud computing based applications has many benefits but it has several security problems like authentication and access control, trust, legal issues, confidentiality, data encryption, early approaches, querying encrypted data, denial of services, malicious insiders, data breach, vulnerability in virtualization, etc.