Proof of retrievability with efficient verification

Abstract

The computationally sound proof (CS proof) is a proof system which reduces the verifier's computation to a level polylogarithmic in that of accepting. If used in cloud computing, CS proof will significantly reduce computation of the client whose computation resources are much more limited than that of the cloud server. We are the first to introduce CS proof belonging to complexity theory into cloud computing, where a protocol for data integrity verification is proposed to reduce the customer's computation. Concretely, the customer's computation is only poly-logarithmic in that of the traditional protocols. However, in our opinion, the significance of this study is not the improved efficiency, but that we introduce a new way to achieve integrity verification. The proposed protocol supports public verification even without the customer's public key and satisfies the security against semi-honest adversaries. The customer's privacy holds against both the cloud and the third-party verifier. The proposed protocol can be considered as a proper application of CS proof to integrity verification in cloud computing.