It has been widely observed that the concept of cloud computing has become one of the major theory in the world of IT industry. Data owner decides to release their burden of storing and maintaining the data locally by storing it over the cloud. Cloud storage moves the owner's data to large data centers which are remotely located on which data owner does not have any control. However, this unique feature of the cloud poses many new security challenges. One of the important concerns that need to be addressed is access control of outsourced data in cloud.