An Improved Lattice-Based Ring Signature with Unclaimable Anonymity in the Standard Model

TL;DR

This paper introduces an improved lattice-based ring signature scheme that ensures unclaimable anonymity, is secure against adversarial key attacks, and has linear signature size growth, enhancing previous work in security and efficiency.

Contribution

It presents a novel lattice-based ring signature scheme with unclaimable anonymity, unforgeability under adversarial key attacks, and linear signature size, improving upon prior schemes.

Findings

Achieves unforgeability against adversarial key attacks.

Signature size grows linearly with ring size.

Provides unclaimable anonymity in the standard model.

Abstract

Ring signatures enable a user to sign messages on behalf of an arbitrary set of users, called the ring, without revealing exactly which member of that ring actually generated the signature. The signer-anonymity property makes ring signatures have been an active research topic. Recently, Park and Sealfon (CRYPTO 19) presented an important anonymity notion named signer-unclaimability and constructed a lattice-based ring signature scheme with unclaimable anonymity in the standard model, however, it did not consider the unforgeable w.r.t. adversarially-chosen-key attack (the public key ring of a signature may contain keys created by an adversary) and the signature size grows quadratically in the size of ring and message. In this work, we propose a new lattice-based ring signature scheme with unclaimable anonymity in the standard model. In particular, our work improves the security and efficiency of Park and Sealfons work, which is unforgeable w.r.t. adversarially-chosen-key attack, and the ring signature size grows linearly in the ring size.