Paper 2026/808 Original: eprint.iacr.org/2026/808 ↗
Efficient Two-Online-Round Secure Comparison in the Plain Model
Abstract
Secure comparison is a fundamental building block frequently employed in various applications of secure multiparty computation, such as secure machine learning. Such protocols based on secret sharing (SS) typically excel in throughput, but they historically suffer from higher (online) round complexity. To address this issue, Attrapadung et al. (AsiaCCS 2022) proposed a protocol with two online rounds in the client-aided model (i.e., assuming a trusted third party in the offline phase), and Lu et al. (USENIX Security 2025) proposed a protocol with three online rounds in the plain model. In this paper, we propose a plaintext comparison protocol with two online rounds in the plain model. While keeping the lowest online round complexity, our protocol also reduces the total bit complexity. For example, for the case of 64-bit integers, the total bit complexity of our protocol is 25.7% of Lu et al.'s protocol and 23.3% of Attrapadung et al.'s protocol adjusted to the plain model.
Metadata
- Available format(s)
PDF- Category
- Cryptographic protocols
- Publication info
- Preprint.
- History
- 2026-08-19: last updated
- 2026-04-24: published
- Short URL
- https://ia.cr/2026/808
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2026/808,
author = {Koji Nuida and Satsuya Ohata},
title = {Efficient Two-Online-Round Secure Comparison in the Plain Model},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/808},
year = {2026},
url = {https://eprint.iacr.org/2026/808}
}