[论文解读] Towards High-Throughput Secure MPC over the Internet: Communication-Efficient Two-Party Protocols and Its Application

Satsuya Ohata, Koji Nuida|arXiv (Cornell University)|Jul 8, 2019

Cryptography and Data Security参考文献 28被引用 1

一句话总结

本文提出了一种基于秘密共享的通信高效、半诚实两方安全计算协议，利用Beaver三元组扩展技术减少通信轮数和带宽。其在线执行阶段的3轮小于比较协议比以往工作快56.1%，通信比特数减少38.4%，使得基于秘密共享的MPC在高吞吐量互联网部署中成为可行方案，尽管计算成本更高。

ABSTRACT

Secure multi-party computation (MPC) allows a set of parties to compute a function jointly while keeping their inputs private. Compared with the MPC based on garbled circuits, some recent research results show that MPC based on secret sharing (SS) works at a very high speed. Moreover, SS-based MPC can be easily vectorized and achieve higher throughput. In SS-based MPC, however, we need many communication rounds for computing concrete protocols like equality check, less-than comparison, etc. This property is not suited for large-latency environments like the Internet (or WAN). In this paper, we construct semi-honest secure communication-efficient two-party protocols. The core technique is Beaver triple extension, which is a new tool for treating multi-fan-in gates, and we also show how to use it efficiently. We mainly focus on reducing the number of communication rounds, and our protocols also succeed in reducing the number of communication bits (in most cases). As an example, we propose a less-than comparison protocol (under practical parameters) with three communication rounds. This is less than a half compared with the previous work. Moreover, the number of communication bits is also $38.4\%$ fewer. As a result, total online execution time is $56.1\%$ shorter than the previous work adopting the same settings. Although the computation costs of our protocols are more expensive than those of previous work, we confirm via experiments that such a disadvantage has small effects on the whole online performance in the typical WAN environments.

研究动机与目标

• 为解决基于秘密共享的MPC中通信轮数过高的问题，该问题在高延迟环境（如互联网）中严重影响性能。
• 在不损害安全性的情况下，同时减少两方安全计算协议中的通信轮数和通信比特数。
• 通过优化MPC协议的在线阶段，实现在广域网（WAN）上的高吞吐量安全计算。
• 评估在实际广域网环境中，计算成本增加与通信效率显著提升之间的权衡。

提出的方法

• 提出Beaver三元组扩展作为一种新技术，高效处理基于秘密共享MPC中的多输入门操作。
• 通过最小化相等性检查和小于比较等基本操作的通信轮数，设计通信优化协议。
• 优化协议结构以减少总通信带宽，尤其在高延迟网络环境中表现更优。
• 采用有限域上的高效算术秘密共享，支持向量化操作，实现高吞吐量。
• 采用半诚实安全模型，专注于通信效率，同时保证正确性和隐私性。
• 在实际参数下进行实验评估，与以往工作进行性能对比。

实验结果

研究问题

• RQ1 Beaver三元组扩展能否有效用于减少基于秘密共享的MPC协议中的通信轮数？
• RQ2 在互联网规模部署中，两方MPC的通信效率最多可提升多少？
• RQ3 减少通信轮数和带宽对广域网环境中整体在线执行时间有何影响？
• RQ4 在实际MPC部署中，计算成本增加与通信开销降低之间的权衡如何？

主要发现

• 所提出的小于比较协议仅需三轮通信，相比以往工作减少超过一半。
• 在实际参数下，通信比特数减少38.4%，显著降低带宽使用。
• 与相同配置下的先前工作相比，总在线执行时间减少56.1%。
• 尽管计算成本更高，但在典型广域网环境中，通信减少带来的性能提升占主导地位。
• 结果证实，通信效率是互联网MPC中的主要瓶颈，优化通信可带来显著的端到端性能提升。