Proofs of retrievability from linearly homomorphic structure-preserving signatures

Abstract

Proofs of retrievability (PoR) enables clients to outsource huge amount of data to cloud servers, and provides an efficient audit protocol, which can be employed to check that all the data is being maintained properly and can be retrieved from the server. In this paper, we present a generic construction of PoR from linearly homomorphic structure-preserving signature (LHSPS), which makes public verification possible. Authenticity and retrievability of our PoR scheme are guaranteed by the unforgeability of LHSPS. We further extend our result to dynamic PoR, which supports dynamic update of outsourced data. Our construction is free of complicated data structures like Merkle hash tree. With an instantiation of a recent LHSPS scheme proposed by Kiltz and Wee (EuroCrypt15), we derive a publicly verifiable (dynamic) PoR scheme. The security is based on standard assumptions and proved in the standard model.