Revocable certificateless Provable Data Possession with identity privacy in cloud storage

Provable Data Possession (PDP) has gained widespread adoption for ensuring the integrity of data in remote cloud storage, where a data owner can delegate a third party auditor (TPA) to perform data auditing. To eliminate key escrow problem or complicated certificate management in classic solutions, numerous certificateless PDP schemes have been proposed while they failed to achieve efficient user revocation and protect user identity privacy. Therefore, we propose ReCIP, a revocable certificateless PDP scheme with identity privacy, where a TPA can perform public data integrity batch verification for a user while learning no useful knowledge about user identity privacy. Technically, we introduce a new user revocation strategy that directly revokes users’ secret keys, with no correlation to the number of data blocks in place for revocation time cost. To further boost the efficiency of ReCIP, we employ a semi-generic online–offline strategy to obtain an online–offline ReCIP (ReCIPoo) to reduce the time cost of tag generation. Moreover, we conduct a formal security proof of ReCIP, where the security is reduced to simple computational Diffie–Hellman problem and discrete logistic problem. Compared to state-of-the-art solutions, our ReCIPoo achieves comparable computation and communication cost while still achieving user revocation and protecting user identity privacy.