A practical third-party auditor prototype for cloud storage service

Abstract

Cloud storage service is a prominent application for recent years. Several famous cloud service providers (CSPs) offer some free volume to users and provide the file synchronization as a convenient function. However, whether the files stored at a CSP are secure or not is a main concern for users. However, it is reported that some famous CSPs lack sound security protection, like no password verification or the missing of stored files. Therefore, how to ensure the security strength of CSPs is an important issue. Nevertheless, most of current CSPs did not provide convictive security mechanism to beef up their security. For example, most of CSPs only claim that they will encrypt the stored files in their storage servers, but the encryption key are picked by the CSPs themselves. In this paper, a practical third-party auditor (TPA) prototype for cloud storage service is proposed to strengthen the properties of confidentiality, integrity, and availability. Moreover, the TPA cannot realize the content of the stored file during verification. Our scheme also provides a useful function to measure the failure time of the CSP.