ROAST: Robust Asynchronous Schnorr Threshold Signatures

Ruffing T, Ronge V, Jin E, Schneider-Bensch J, Schröder D (2022)

Publication Language: English

Publication Type: Conference contribution, Original article

Publication year: 2022

Publisher: Association for Computing Machinery

Series: CCS '22: Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security

City/Town: New York, NY, United States

Pages Range: 2551–2564

Conference Proceedings Title: CCS '22

Event location: Los Angeles US

ISBN: 978-1-4503-9450-5


DOI: 10.1145/3548606.3560583

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Bitcoin and other cryptocurrencies have recently introduced support for Schnorr signatures whose cleaner algebraic structure, as compared to ECDSA, allows for simpler and more practical constructions of highly demanded ''t-of-n'' threshold signatures. However, existing Schnorr threshold signature schemes still fall short of the needs of real-world applications due to their assumption that the network is synchronous and due to their lack of robustness, i.e., the guarantee that t honest signers are able to obtain a valid signature even in the presence of other malicious signers who try to disrupt the protocol. This hinders the adoption of threshold signatures in the cryptocurrency ecosystem, e.g., in second-layer protocols built on top of cryptocurrencies.

In this work, we propose ROAST, a simple wrapper that turns a given threshold signature scheme into a scheme with a robust and asynchronous signing protocol, as long as the underlying signing protocol is semi-interactive (i.e., has one preprocessing round and one actual signing round), provides identifiable aborts, and is unforgeable under concurrent signing sessions. When applied to the state-of-the-art Schnorr threshold signature scheme FROST, which fulfills these requirements, we obtain a simple, efficient, and highly practical Schnorr threshold signature scheme.

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Ruffing, T., Ronge, V., Jin, E., Schneider-Bensch, J., & Schröder, D. (2022). ROAST: Robust Asynchronous Schnorr Threshold Signatures. In Heng Yin, Angelos Stavrou (Eds.), CCS '22 (pp. 2551–2564). Los Angeles, US: New York, NY, United States: Association for Computing Machinery.


Ruffing, Tim, et al. "ROAST: Robust Asynchronous Schnorr Threshold Signatures." Proceedings of the ACM CCS 2022, Los Angeles Ed. Heng Yin, Angelos Stavrou, New York, NY, United States: Association for Computing Machinery, 2022. 2551–2564.

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