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OciorABA: Improved Error-Free Asynchronous Byzantine Agreement via Partial Vector Agreement

Abstract

In this work, we propose an error-free, information-theoretically secure multi-valued asynchronous Byzantine agreement (ABA) protocol, called OciorABA. This protocol achieves ABA consensus on an \ell-bit message with an expected communication complexity of O(n+n3logq)O(n\ell + n^3 \log q ) bits and an expected round complexity of O(1)O(1) rounds, under the optimal resilience condition n3t+1n \geq 3t + 1 in an nn-node network, where up to tt nodes may be dishonest. Here, qq denotes the alphabet size of the error correction code used in the protocol. In our protocol design, we introduce a new primitive: asynchronous partial vector agreement (APVA). In APVA, the distributed nodes input their vectors and aim to output a common vector, where some of the elements of those vectors may be missing or unknown. We propose an APVA protocol with an expected communication complexity of O(n3logq)O( n^3 \log q ) bits and an expected round complexity of O(1)O(1) rounds. This APVA protocol serves as a key building block for our OciorABA protocol.

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