Enabling Cloud Storage Auditing with KeyExposure Resilience under Continual KeyLeakage Abstract   Cloud storage auditing is a service that is usually provided to enable clients to verify the integrity of their data stored in the cloud. However, clients risk exposing their secret key. To address the problem of key exposure, researchers have provided xe2x80x9cForward Securityxe2x80x9d by dividing the entire lifetime of the secret key into several periods and updating the secret key within each of these periods. Forward security can ensure the validity of authenticators before the period in which the secret key is fully exposed. However, the security of these protocols can be broken by launching sidechannel attacks to leak the secret key partially rather than fully. In this study, we focus on implementing measures in cloud storage auditing to protect against sidechannel attacks in practice. We formalize the definition and security model of a cloud storage auditing protocol, which supports forward security under continual keyleakage, and construct the first protocol. Our protocol remains secure even if an adversary obtains partial leakage of the secret key during a period. In addition, if the secret key were to be fully disclosed in a certain period, our protocol would maintain forward security. Therefore, the proposed protocol provides stronger security compared with existing protocols.

IdentityBased Public Auditing Scheme for Cloud Storage with Strong KeyExposure Resilience 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 managementverification. These schemes also incur high computation time during integrity verification of the data blocks. The Identitybased 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 Identitybased Provable Data Possession scheme is proposed. It protects the security of Identitybased 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.