OciorMVBA: Near-Optimal Error-Free Asynchronous MVBA
Jinyuan Chen
TL;DR
The paper addresses asynchronous MVBA with external validity in a cryptography-free setting by introducing OciorMVBA and two variants, OciorMVBArr and OciorMVBAh, each achieving IT-secure, error-free consensus under different resilience regimes. The main approach merges well-established building blocks (UA, HMDM/SHMDM, ABBBA, ABBA, ACID) into a recursive or parallel architecture, complemented by common coins and error-correction or hash-based vector commitments to deliver near-optimal communication, rounds, and reliability. Key contributions include formal protocol designs, rigorous performance analyses, and a comparative framework showing how different ECC and hashing strategies affect alphabet size, latency, and resilience. The work has practical impact for scalable, secure asynchronous consensus in distributed systems without relying on signatures or hash functions, while offering explicit trade-offs via OciorMVBA, OciorMVBArr, and OciorMVBAh.
Abstract
In this work, we propose an error-free, information-theoretically secure, asynchronous multi-valued validated Byzantine agreement (MVBA) protocol, called OciorMVBA. This protocol achieves MVBA consensus on a message $\boldsymbol{w}$ with expected $O(n |\boldsymbol{w}|\log n + n^2 \log q)$ communication bits, expected $O(n^2)$ messages, expected $O(\log n)$ rounds, and expected $O(\log n)$ common coins, under optimal resilience $n \geq 3t + 1$ in an $n$-node network, where up to $t$ nodes may be dishonest. Here, $q$ denotes the alphabet size of the error correction code used in the protocol. When error correction codes with a constant alphabet size (e.g., Expander Codes) are used, $q$ becomes a constant. An MVBA protocol that guarantees all required properties without relying on any cryptographic assumptions, such as signatures or hashing, except for the common coin assumption, is said to be information-theoretically secure (IT secure). Under the common coin assumption, an MVBA protocol that guarantees all required properties in all executions is said to be error-free. We also propose another error-free, IT-secure, asynchronous MVBA protocol, called OciorMVBArr. This protocol achieves MVBA consensus with expected $O(n |\boldsymbol{w}| + n^2 \log n)$ communication bits, expected $O(1)$ rounds, and expected $O(1)$ common coins, under a relaxed resilience (RR) of $n \geq 5t + 1$. Additionally, we propose a hash-based asynchronous MVBA protocol, called OciorMVBAh. This protocol achieves MVBA consensus with expected $O(n |\boldsymbol{w}| + n^3)$ bits, expected $O(1)$ rounds, and expected $O(1)$ common coins, under optimal resilience $n \geq 3t + 1$.