Publication Type
Conference Proceeding Article
Version
publishedVersion
Publication Date
11-2021
Abstract
Two-party ECDSA signatures have received much attention due to their widespread deployment in cryptocurrencies. Depending on whether or not the message is required, we could divide two-party signing into two different phases, namely, offline and online. Ideally, the online phase should be made as lightweight as possible. At the same time, the cost of the offline phase should remain similar to that of a normal signature generation. However, the existing two-party protocols of ECDSA are not optimal: either their online phase requires decryption of a ciphertext, or their offline phase needs at least two executions of multiplicative-to-additive conversion which dominates the overall complexity. This paper proposes an online-friendly two-party ECDSA with a lightweight online phase and a single multiplicative-to-additive function in the offline phase. It is constructed by a novel design of a re-sharing of the secret key and a linear sharing of the nonce. Our scheme significantly improves previous protocols based on either oblivious transfer or homomorphic encryption. We implement our scheme and show that it outperforms prior online-friendly schemes (i.e., those have lightweight online cost) by a factor of roughly 2 to 9 in both communication and computation. Furthermore, our two-party scheme could be easily extended to the 2-out-of-n threshold ECDSA.
Keywords
ECDSA, threshold signature, two-party signature, blockchain, zero knowledge proof
Discipline
Information Security
Research Areas
Cybersecurity
Areas of Excellence
Digital transformation
Publication
CCS '21: Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security, Virtual Conference, November 15-19
First Page
558
Last Page
573
ISBN
9781450384544
Identifier
10.1145/3460120.3484803
Publisher
ACM
City or Country
New York
Citation
XUE, Haiyang; AU, Ho Man; XIE, Xiang; YUEN, Hon Tsz; and CUI, Handong.
Efficient online-friendly two-party ECDSA signature. (2021). CCS '21: Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security, Virtual Conference, November 15-19. 558-573.
Available at: https://ink.library.smu.edu.sg/sis_research/9188
Copyright Owner and License
Authors
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Additional URL
https://doi.org/10.1145/3460120.3484803