Cryptology ePrint Archive: Report 2019/1271

Round-optimal Verifiable Oblivious Pseudorandom Functions From Ideal Lattices

Martin R. Albrecht and Alex Davidson and Amit Deo and Nigel P. Smart

Abstract: Verifiable Oblivious Pseudorandom Functions (VOPRFs) are protocols that allow a client to learn verifiable pseudorandom function (PRF) evaluations on inputs of their choice. The PRF evaluations are computed by a server using their own secret key. The security of the protocol prevents both the server from learning anything about the client's input, and likewise the client from learning anything about the server's key. VOPRFs have many applications including password-based authentication, secret-sharing, anonymous authentication and efficient private set intersection. In this work, we construct the first round-optimal (online) VOPRF protocol that retains security from well-known subexponential lattice hardness assumptions. Our protocol requires constructions of non-interactive zero-knowledge arguments of knowledge (NIZKAoK). Using recent developments in the area of post-quantum zero-knowledge arguments of knowledge, we show that our VOPRF may be securely instantiated in the quantum random oracle model. We construct such arguments as extensions of prior work in the area of lattice-based zero-knowledge proof systems.

Category / Keywords: cryptographic protocols / oblivious pseudorandom function, lattices, post-quantum

Original Publication (with major differences): IACR-PKC-2021

Date: received 1 Nov 2019, last revised 1 Mar 2021

Contact author: martin albrecht at royalholloway ac uk, adavidson at lip pt, amit deo at ens-lyon fr, nigel smart at kuleuven be

Available format(s): PDF | BibTeX Citation

Note: Full version following PKC 2021 acceptance

Version: 20210301:100738 (All versions of this report)

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