Cloud is the cluster of geographically connected network bearing information. Cloud Computing make feasible for multiple users to, share common computing resources, and to access and store their personal and business information. In cloud computing We stored data on server side as well on client side. Application like Dropbox provide service in such a way that data on server and on client machine are synchronous. So implementing security become very necessary on client side. Traditional algorithm failed once key is compromised. User behavior profiling and decoy technology provide an alternate way to secure data on server which is more efficient and secure. There are many algorithm on user behavior profiling and decoy technology but no one address the problem of efficiently delivering the decoy file in such a way the intruder not able to recognize the difference between the genuine and decoy file, once the anonymous behavior of the user identified. We proposed a system in which we going to use the two technology together i.e user behavior profiling and decoy technology and we also proposed the mechanism by which we generate the decoy file in such a way it matches the content of the genuine file up to the accuracy of 98 percent.