Identity-Based Public Auditing Scheme for Cloud Storage with Strong Key-Exposure Resilience

Abstract

Secured storage system is a critical component in cloud computing. Cloud clients use cloud auditing schemes to verify the integrity of data stored in the cloud. But with the exposure of the auditing secret key to the Cloud Service Provider, cloud auditing becomes unsuccessful, however strong the auditing schemes may be. Therefore, it is essential to prevent the exposure of auditing secret keys, and even if it happens, it is necessary to minimize the damage caused. The existing cloud auditing schemes that are strongly resilient to key exposure are based on Public Key Infrastructure and so have challenges of certificate management/verification. These schemes also incur high computation time during integrity verification of the data blocks. The Identity-based schemes eliminate the usage of certificates but limit the damage due to key exposure, only in time periods earlier to the time period of the exposed key. Some of the key exposure resilient schemes do not provide support for batch auditing. In this paper, an Identity-based Provable Data Possession scheme is proposed. It protects the security of Identity-based cloud storage auditing in time periods both earlier and later to the time period of the exposed key. It also provides support for batch auditing. Analysis shows that the proposed scheme is resistant to the replace attack of the Cloud Service Provider, preserves the data privacy against the Third Party Auditor, and can efficiently verify the correctness of data.