Dynamic Proofs of Retrievability with improved worst case overhead

Proofs of Retrievability (POR) is a scheme to build a verifiable storage on a remote server that a client can access the data randomly, and periodically execute an efficient Audit protocol to ensure that the data is intact. In dynamic POR, the difficulties are to maintain the latest version of the data while achieving efficient Update and Audit. In this paper, we propose PDPOR that achieves the best worse-case overhead O(logN) for both Write and Audit protocols together with the best worse-case bandwidth. We also prove the security of DPOR using simpler techniques.