Cloud computing gives customers the illusion of infinite computing sources which are available from anywhere, anytime, on demand. However the capability of selectively sharing encrypted data with distinctive users thru public cloud storage can also greatly ease security concerns over inadvertent information leaks inside the cloud. The desired flexibility of sharing any group of particular selected documents with any group of users demands different keys for encryption to be used for any different documents. So many trapdoors are created in the cloud. In this paper review helps the research how to secure data in cloud environment.