Fast Multiparty Threshold ECDSA with Fast Trustless Setup

A threshold signature scheme enables distributed signing among n players such that any subgroup of size t + 1 can sign, whereas any group with t or fewer players cannot. While there exist previous threshold schemes for the ECDSA signature scheme, we present the first protocol that supports multiparty signatures for any t ≤ n with efficient, dealerless key generation. Our protocol is faster than previous solutions and significantly reduces the communication complexity as well. We prove our scheme secure against malicious adversaries with a dishonest majority. We implemented our protocol, demonstrating its efficiency and suitability to be deployed in practice. This is a minor revision of our paper [16] that appeared at ACM CCS 2018. § Steven Goldfeder has since joined Cornell Tech/IC3