In past few years, cloud computing is one of the popular paradigm to host and deliver services over Internet. It is having popularity by offering multiple computing services as cloud storage, cloud hosting and cloud servers etc., for various types of businesses as well as in academics. Though there are several benefits of cloud computing, it suffers from security and privacy challenges. Privacy of cloud system is a serious concern for the customers. Considering the privacy within the cloud there are numerous threats to the user's sensitive data on cloud storage.