MPC with Synchronous Security and Asynchronous Responsiveness

Liu-Zhang, Chen-Da; Loss, Julian; Maurer, Ueli; Moran, Tal; Tschudi, Daniel

doi:10.1007/978-3-030-64840-4_4

Cited by 6 publications

(2 citation statements)

References 40 publications

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“…They also defined a notion of optimistic responsiveness to capture a protocol achieving responsiveness in some optimistic condition. Liu-Zhang et al explored the relation of resiliences in the fast and slow pathes in the MPC setting [21], and showed that there is a tradeoff between the two resilience bounds. They also proposed a general compiler that compiles a synchronous protocol with a asynchronous protocol to enjoy the responsiveness that asynchronous protocols can provide.…”

Section: Related Workmentioning

confidence: 99%

An optimisation for a two‐round good‐case latency protocol

Zhang

Guo

et al. 2023

IET Information Security

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Byzantine broadcast is a fundamental primitive in distributed computing. A highly efficient Byzantine broadcast protocol, motivated by the real-world performance of practical state machine replication protocols, is increasingly needed. This article focuses on the state-of-the-art partially synchronous Byzantine broadcast protocol proposed by Abraham et al. (PODC'21), which achieves optimal good-case latency of two rounds and optimal resilience of n ≥ 5f − 1 in this setting. Each step of the protocol is analysed, and then improved by cutting down the number of messages required to be collected and transmitted in the heaviest step of the protocol by about half, without adding any extra cost. This benefits from a new property, named "spread", that we identify and extract from the original protocol. It helps us to eliminate non-essential work in its view-change procedure. The authors also show that no further reduction is possible without violating security. A prototype is implemented and the performances of improved and original protocols are evaluated in the same environment. The results show that our improvement can achieve about 50% lower communication cost and 40% shorter latency at a scale of 100 replicas. The latency gap becomes wider as the scale further increases.

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Section: Related Workmentioning

confidence: 99%

An optimisation for a two‐round good‐case latency protocol

Zhang

Guo

et al. 2023

IET Information Security

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“…A different line of work [39,40,35,34] has recently investigated protocols that achieve responsiveness. These protocols operate under a synchronous network, and provide the additional guarantee that parties obtain output as fast as the network delay allows.…”

Section: Related Workmentioning

confidence: 99%

Round-Efficient Byzantine Agreement and Multi-party Computation with Asynchronous Fallback

Deligios

Hirt

Liu-Zhang

2021

Lecture Notes in Computer Science

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Protocols for Byzantine agreement (BA) and secure multi-party computation (MPC) can be classified according to the underlying communication model. The two most commonly considered models are the synchronous one and the asynchronous one. Synchronous protocols typically lose their security guarantees as soon as the network violates the synchrony assumptions. Asynchronous protocols remain secure regardless of the network conditions, but achieve weaker security guarantees even when the network is synchronous. Recent works by Blum, Katz and Loss [TCC'19], and Blum, Liu-Zhang and Loss [CRYPTO'20] introduced BA and MPC protocols achieving security guarantees in both settings: security up to ts corruptions in a synchronous network, and up to ta corruptions in an asynchronous network, under the provably optimal threshold trade-offs ta ≤ ts and ta + 2ts < n. However, current solutions incur a high synchronous round complexity when compared to state-of-the-art purely synchronous protocols. When the network is synchronous, the round complexity of BA protocols is linear in the number of parties, and the round complexity of MPC protocols also depends linearly on the depth of the circuit to evaluate. In this work, we provide round-efficient constructions for both primitives with optimal resilience: fixed-round and expected constant-round BA protocols, and an MPC protocol whose round complexity is independent of the circuit depth.

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