Privacy-preserving certificateless public auditing supporting different auditing frequencies

Public auditing enables a verifier, say a third party auditor (TPA), to verify whether the cloud correctly stores the user's cloud data. To date, a lot of public auditing schemes have been proposed. However, none of them consider the problem of auditing frequency. In practice, to reduce the cost of auditing service and avoid waste of resources, the users prefer to frequently verify the integrity of high-value data and check the integrity of low-value data with low frequency. In this paper, we propose a privacy-preserving certificateless public auditing scheme supporting different auditing frequencies. In this scheme, a novel auditing strategy is provided, in which the TPA is allowed to complete auditing tasks on high-value and low-value files with different auditing frequencies. The user's privacy can be achieved by utilizing permutation technology to confuse the real file index. Hence, the TPA cannot distinguish the files with high value. We also use the random masking technology to mask the auditing proof, which guarantees the privacy of user data. The proposed scheme avoids the complicated certificate management and key escrow since it is designed in the certificateless cryptography. We prove that the proposed scheme is secure. The experimental results are shown to validate the efficiency of the proposed scheme.(c) 2023 Elsevier Ltd. All rights reserved.