Paper 2021/113

Improvement of Secure Multi-Party Multiplication of (k,n) Threshold Secret Sharing Using Only N=k Servers (Revised Version)

Ahmad Akmal Aminuddin Mohd Kamal and Keiichi Iwamura

Abstract

Secure multi-party computation (MPC) allows a set of n servers to jointly compute an arbitrary function of their inputs, without revealing these inputs to each other. A (k,n) threshold secret sharing is a protocol in which a single secret is divided into n shares and the secret can be recovered from a threshold k shares. Typically, multiplication of (k,n) secret sharing will result in increase of polynomial degree from k-1 to 2k-2, thus increasing the number of shares required from k to 2k-1. Since each server typically hold only one share, the number of servers required in MPC will also increase from k to 2k-1. Therefore, a set of n servers can compute multiplication securely if the adversary corrupts at most k-1<n/2 of the servers. In this paper, we differentiate the number of servers N required and parameter n of (k,n) secret sharing scheme, and propose a method of computing (k-1) sharing of multiplication ab by using only N=k servers. By allowing each server to hold two shares, we realize MPC of multiplication with the setting of N=k,n&#8805;2k-1. We also show that our proposed method is information theoretic secure against a semi-honest adversary.

Note: **This is the revised version of the paper submitted in the Proceedings of the 7th International Conference on Information Systems Security and Privacy (ICISSP 2021). The revised version had corrected a few mistakes in the original publication.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Published elsewhere. Minor revision. 7th International Conference on Information Systems Security and Privacy (ICISSP 2021)
Keywords
Secure Multi-Party ComputationMPCSecure MultiplicationSecret Sharing
Contact author(s)
ahmad @ sec ee kagu tus ac jp
History
2021-02-01: received
Short URL
https://ia.cr/2021/113
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2021/113,
      author = {Ahmad Akmal Aminuddin Mohd Kamal and Keiichi Iwamura},
      title = {Improvement of Secure Multi-Party Multiplication of (k,n) Threshold Secret Sharing Using Only N=k Servers (Revised Version)},
      howpublished = {Cryptology ePrint Archive, Paper 2021/113},
      year = {2021},
      note = {\url{https://eprint.iacr.org/2021/113}},
      url = {https://eprint.iacr.org/2021/113}
}
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