Cloud computing provides on demand services to its purchasers. Knowledge storage is among one in every of the first services provided by cloud computing. Cloud service supplier hosts the information of knowledge owner on their server and user will access their data from these servers. As data, homeowners and servers are completely different identities, the paradigm of knowledge storage brings up several security challenges. Associate in Nursing freelance mechanism is needed to form certain that knowledge is properly hosted in to the cloud storage server. During this paper, we are going to discuss the various techniques that are used for secure knowledge storage on cloud.