Proofs of Retrievability with Public Verifiability from Lattices

Abstract:  Proof of Retrievability (POR) is an important cryptographic primitive that has attracted considerable attention in the research community for its ability to enable users to audit the integrity of outsourced files on cloud servers without retrieving them. A POR scheme with public verifiability further enhances usability by allowing users to delegate the auditing task to a third party, making it highly desirable for a wide range of applications. However, most existing publicly verifiable POR schemes derive their security from the computational hardness of discrete logarithm or factoring, making them vulnerable to quantum attacks. Although it is possible to construct quantum-resistant POR schemes with public verifiability upon hash trees or general lattices, the resulting schemes often exhibit performance limitations when compared to existing constructions, thereby limiting their deployment in real-world applications. In this work, we address this gap by constructing a publicly verifiable POR scheme on structured lattices. We show that our scheme is provably secure in the random oracle model under the Ring-LWE and Ring-SIS assumptions. We provide an implementation of our scheme and the experimental results show that its performance is comparable to certain well-known constructions based on traditional assumptions.
Keywords: Proof of Retrievability; Lattice; Implementation
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