Paper 2025/2290

Towards Practical Multi-Party Hash Chains using Arithmetization-Oriented Primitives - With Applications to Threshold Hash-Based Signatures

Abstract

Despite their simplicity and quantum-resistant security properties, the deployment of hash chains in distributed settings through secure multi-party computation (MPC) has been demonstrated to be impractical when employing traditional hash functions (i.e., SHA2/SHA3) due to their high number of non-linear gates which lead to heavy computational costs. In this work, we present a comprehensive evaluation of hash chain computations over MPC using arithmetization-oriented (AO) primitives, specifically focusing on the Poseidon2 family of hash functions. We systematically analyze the MPC-friendliness of various Poseidon2 instantiations across different prime fields and parameter choices to minimize both multiplicative depth and preprocessing requirements. We conduct extensive benchmarks using the MP-SPDZ framework across three state-of-the-art MPC protocols under varying network conditions and adversarial models. We further explore practical applications to threshold cryptography, presenting optimized implementations of threshold hash-based signatures that achieve signing times less than 1 second in a 3-party setting for practical parameter sets. Specifically, we demonstrate how structural parallelism in hash-based signatures can be exploited to batch independent hash chains within a single MPC execution, and introduce a time-memory trade-off that enables non-interactive online signature generation through systematic precomputation of all chain intermediates. Our work suggests the practical viability of moderate length AO-based hash chains for MPC applications.