Now-a-days, users no longer have physical presence of the outsourced data which makes the data security stronger. Moreover, users should be able to just use the cloud storage as if it is local, without worrying about the integrity. Therefore several critical security challenges are occur and motivate the researchers for further investigations. Because of these critical issues users can resort to a Third Party Auditor (TPA) to check the integrity of outsourced data. To securely introduce an effective TPA, the auditing process should bring in no new vulnerabilities towards user data privacy, and introduce no additional online burden to user.