Secure Storage and Retrieval of Data without Original Files in Cloud Architectures Subtitle as needed

When a client uses the service which is offered by cloud storage providers, he might worry about how to retrieve their original files securely. Relieving client’s storage burden and successfully retrieving data on demand are the ultimate purposes of cloud storage service. To achieve the above two aims, in this paper we propose a specific way to store and retrieve the out stored data in cloud storage. We utilize an efficient publicly verifiable secret sharing (PVSS) scheme to divide the file into multiple parts and store them among a group of servers, then using the recovery algorithm in PVSS, the users can retrieve their stored files successfully from any k qualified servers without the need of holding original file. Thus, the storage burden of the user is relieved much. And we show that the security of the protocol is closely related to the computational Diffie-Hellman problem.