Towards Scalable Threshold Cryptosystems
Name
scalable_thresh.pdf
Description
Accepted version
Size
1.16 MB
Format
Adobe PDF
Checksum (MD5)
68abf55ab63f0e0eb98286939d4160af
Author(s)
Tomescu, Alin
Chen, Robert
Zheng, Yiming
Abraham, Ittai
Pinkas, Benny
Gueta, Guy Golan
Devadas, Srinivas
Date Issued
July 2020
Journal
2020 IEEE Symposium on Security and Privacy
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Citation
Tomescu, Alin et al. "Towards Scalable Threshold Cryptosystems." 2020 IEEE Symposium on Security and Privacy, May 2020, San Francisco, California, Institute of Electrical and Electronics Engineers, July 2020. © 2020 IEEE
Version
Author's final manuscript
Abstract
The resurging interest in Byzantine fault tolerant systems will demand more scalable threshold cryptosystems. Unfortunately, current systems scale poorly, requiring time quadratic in the number of participants. In this paper, we present techniques that help scale threshold signature schemes (TSS), verifiable secret sharing (VSS) and distributed key generation (DKG) protocols to hundreds of thousands of participants and beyond. First, we use efficient algorithms for evaluating polynomials at multiple points to speed up computing Lagrange coefficients when aggregating threshold signatures. As a result, we can aggregate a 130,000 out of 260,000 BLS threshold signature in just 6 seconds (down from 30 minutes). Second, we show how "authenticating"such multipoint evaluations can speed up proving polynomial evaluations, a key step in communication-efficient VSS and DKG protocols. As a result, we reduce the asymptotic (and concrete) computational complexity of VSS and DKG protocols from quadratic time to quasilinear time, at a small increase in communication complexity. For example, using our DKG protocol, we can securely generate a key for the BLS scheme above in 2.3 hours (down from 8 days). Our techniques improve performance for thresholds as small as 255 and generalize to any Lagrange-based threshold scheme, not just threshold signatures. Our work has certain limitations: we require a trusted setup, we focus on synchronous VSS and DKG protocols and we do not address the worst-case complaint overhead in DKGs. Nonetheless, we hope it will spark new interest in designing large-scale distributed systems.
MIT Department
Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1109/sp40000.2020.00059
