Paper 2026/1941 Original: eprint.iacr.org/2026/1941 ↗

DualMS 2.0: Practical Lattice-Based Two-Round Fiat-Shamir Multi-Signature with Better Efficiency

Abstract

We present a more practical lattice-based two-round Fiat–Shamir multi-signature scheme that achieves a substantial reduction in signature size compared with DualMS, the state-of-the-art two-round lattice-based Fiat-Shamir multi-signature. Our main technical contribution is a new simulation technique that enables individual signatures to be sampled from distributions with smaller parameters, yielding significant concrete efficiency gains. In addition, through applying the specific modulus-rounding optimization, we can further reduce the sizes of signature and aggregated public-key. Concretely, compared with DualMS, our scheme reduces the signature size by 62.4%, and the aggregated public-key size by 37.5%. For example, with 32 signers, our signature and aggregated public-key are approximately 8.86 KB and 4.38 KB (versus 19.72 KB and 6.94 KB in DualMS) respectively, and for 1024 signers, our signature and aggregated public-key are approximately 11.62 KB and 6.56 KB (versus 30.91 KB and 10.5 KB in DualMS). Moreover, in order to show the practicality of our scheme, we implement our scheme in Go language using the open-source library Lattigo, and then analyze its performance on computation and communication, through both local and WAN experiments. To the best of our knowledge, our scheme achieves the smallest concrete signature sizes among all existing two-round lattice-based multi-signature schemes following Fiat–Shamir with abort paradigm. These results suggest that our scheme is practical and well-suited for real-world deployment.