Welcome to the resource topic for 2025/2078
Title:
Broadcast for Dynamic Committees without Trusted Setup
Authors: Gabriel Dettling, Elisaweta Masserova, Chen-Da Liu-Zhang, Matthieu Rambaud, Antoine Urban
Abstract:A significant number of works have considered the problem of multi-party computation over dynamic committees in synchronous networks, including YOSO MPC [Crypto’21], Fluid MPC [Crypto’21], SCALES MPC [TCC’22] and Layered MPC [Crypto’23]. However, prior works assume that every party has access to an ideal synchronous broadcast channel towards the next committee.
While this assumption is partly justified due to the seminal work of Garay [WDAG'94] stating that deterministic broadcast with dynamic committees is impossible, it is open whether there are randomized solutions.
We answer this question in the affirmative, by providing a complete characterization of broadcast with dynamic committees. We use the formalization introduced in the Layered MPC setting and achieve the following results for layered broadcast: %first, a protocol for $t3$ with statistical security and no setup; second, a protocol for $t2$ assuming a plain PKI for signatures; third, an impossibility result stating that broadcast is impossible for $t\ge n/2$.
- A statistically secure protocol tolerating t3 corruptions with no setup.
- A computationally secure protocol tolerating t2 corruptions, assuming only a plain PKI for signatures.
- A matching impossibility result showing that broadcast is impossible for t \geq n/2 corruptions.
ePrint: https://eprint.iacr.org/2025/2078
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