IACR News item: 24 September 2023
Sermin Kocaman, Younes Talibi Alaoui
ePrint Report
Distributing the Elliptic Curve Digital Signature Algorithm
(ECDSA) has received increased attention in past years due to the wide
range of applications that can benefit from this, particularly after the
popularity that the blockchain technology has gained. Many schemes
have been proposed in the literature to improve the efficiency of multi-
party ECDSA. Most of these schemes either require heavy homomorphic
encryption computation or multiple executions of a functionality that
transforms Multiplicative shares to Additive shares (MtA). Xue et al.
(CCS 2021) proposed a 2-party ECDSA protocol secure against mali-
cious adversaries and only requires one execution of MtA, with an online
phase that consists of only one party sending one field element to the
other party with a computational overhead dominated by the verifica-
tion step of the signature scheme. We propose a novel protocol, based
on the assumption that the Computational Diffie-Hellman problem is
hard, that offers the same online phase performance as the protocol of
Xue et al., but improves the offline phase by reducing the computational
cost by one elliptic curve multiplication and the communication cost by
two field elements. To the best of our knowledge, our protocol offers the
most efficient offline phase for a two-party ECDSA protocol with such
an efficient online phase.
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