Abstract: Security for the data which is stored on the cloud by user is very important issue. User may expect some security for their data from the cloud service provider, there can be serious issues regarding data security between user and service provider. To solve this kind of issues, we can use third party as an auditor. Here we have analyzed different ways to ensure secure data storage in cloud. We are going to provide the security to the user’s data by using encryption technique. For this we are using the Advanced Encryption Standard algorithm for encryption and decryption. But when Cloud Service Provider has both encryption and decryption keys, there is threat to security and privacy of data. CSP may pass the user data without user’s knowledge. For auditing we are introducing Third Party Auditor. Here the data will be encrypted at user side and will be in encrypted form over network and to TPA. TPA will verify the data before storing it on the cloud. There are large numbers of users of cloud computing who are accessing and modifying the data and they need the reliable service provider who can provide complete security for their data. So the TPA will audit the data and check the data integrity of client’s data. No one else rather than user is able to view data. But if someone tries to access the data, and then there will be a file alert generated to the user. Hence user will have more elaborated view over his data privacy. In this paper we are providing solution for the user who needs security and privacy for their data.

Keywords: Third Party Auditor (TPA), Cloud Service Provider (CSP), Data Integrity, Encryption.