An alternative approach to public cloud data auditing supporting data dynamics

Public cloud data auditing allows a user to delegate an auditing job to a third party who is responsible for verifying whether a cloud server has faithfully stored a file or not. Proof of retrievability (PoR) is a widely used protocol for this kind of job. To the best of our knowledge, in the publicly verifiable setting with supporting data dynamics, all known PoR schemes are either rely on the random oracles or are built in the standard model but require nonstandard assumptions. In this paper, we present a scheme which explores the linear homomorphic signature and the sequence Merkle hash tree to construct the homomorphic linear authenticator for the PoR. The security of our proposed scheme can be proved in the standard model, assuming the hash function is collision resilient and the computational Diffie–Hellman assumption holds. The scheme also supports data modification, data insertion and data deletion. Furthermore, our technique can also be regarded as a novel paradigm by combining the homomorphic signature and authenticated data structure (with certain properties) to construct the homomorphic linear authenticator for the PoR protocols.