Practical Schnorr Threshold Signatures Without the Algebraic Group Model
Chu TTH, Gerhart P, Ruffing T, Schröder D (2023)
Publication Type: Conference contribution
Publication year: 2023
Journal
Publisher: Springer Science and Business Media Deutschland GmbH
Book Volume: 14081 LNCS
Pages Range: 743-773
Conference Proceedings Title: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Event location: Santa Barbara, CA, USA
ISBN: 9783031385568
DOI: 10.1007/978-3-031-38557-5_24
Abstract
Threshold signatures are digital signature schemes in which a set of n signers specify a threshold t such that any subset of size t is authorized to produce signatures on behalf of the group. There has recently been a renewed interest in this primitive, largely driven by the need to secure highly valuable signing keys, e.g., DNSSEC keys or keys protecting digital wallets in the cryptocurrency ecosystem. Of special interest is FROST, a practical Schnorr threshold signature scheme, which is currently undergoing standardization in the IETF and whose security was recently analyzed at CRYPTO’22. We continue this line of research by focusing on FROST’s unforgeability combined with a practical distributed key generation (DKG) algorithm. Existing proofs of this setup either use non-standard heuristics, idealized group models like the AGM, or idealized key generation. Moreover, existing proofs do not consider all practical relevant optimizations that have been proposed. We close this gap between theory and practice by presenting the Schnorr threshold signature scheme Olaf, which combines the most efficient known FROST variant FROST3 with a variant of Pedersen’s DKG protocol (as commonly used for FROST), and prove its unforgeability. Our proof relies on the AOMDL assumption (a weaker and falsifiable variant of the OMDL assumption) and, like proofs of regular Schnorr signatures, on the random oracle model.
Authors with CRIS profile
Thi Thu Hien Chu
Lehrstuhl für Informatik 13 (Angewandte Kryptographie)
Paul Gerhart
Lehrstuhl für Informatik 13 (Angewandte Kryptographie)
Dominique Schröder
Fachbereich Wirtschaftswissenschaften
Involved external institutions
Canada (CA)How to cite
APA:
Chu, T.T.H., Gerhart, P., Ruffing, T., & Schröder, D. (2023). Practical Schnorr Threshold Signatures Without the Algebraic Group Model. In Helena Handschuh, Anna Lysyanskaya (Eds.), Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (pp. 743-773). Santa Barbara, CA, USA: Springer Science and Business Media Deutschland GmbH.
MLA:
Chu, Thi Thu Hien, et al. "Practical Schnorr Threshold Signatures Without the Algebraic Group Model." Proceedings of the Advances in Cryptology – CRYPTO 2023 - 43rd Annual International Cryptology Conference, CRYPTO 2023, Proceedings, Santa Barbara, CA, USA Ed. Helena Handschuh, Anna Lysyanskaya, Springer Science and Business Media Deutschland GmbH, 2023. 743-773.
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