Aleph: Efficient Atomic Broadcast in Asynchronous Networks with Byzantine Nodes

TL;DR

Aleph introduces an efficient asynchronous Byzantine broadcast protocol that improves latency and removes the need for a trusted dealer, enhancing blockchain transaction ordering with formal correctness and security guarantees.

Contribution

The paper presents Aleph, a novel ABFT protocol that reduces latency and eliminates trusted setup, advancing asynchronous Byzantine fault-tolerant systems for blockchain applications.

Findings

Reduces asymptotic latency compared to HoneyBadgerBFT

Matches optimal communication complexity

Does not require a trusted dealer due to a trustless randomness beacon

Abstract

The spectacular success of Bitcoin and Blockchain Technology in recent years has provided enough evidence that a widespread adoption of a common cryptocurrency system is not merely a distant vision, but a scenario that might come true in the near future. However, the presence of Bitcoin's obvious shortcomings such as excessive electricity consumption, unsatisfying transaction throughput, and large validation time (latency) makes it clear that a new, more efficient system is needed. We propose a protocol in which a set of nodes maintains and updates a linear ordering of transactions that are being submitted by users. Virtually every cryptocurrency system has such a protocol at its core, and it is the efficiency of this protocol that determines the overall throughput and latency of the system. We develop our protocol on the grounds of the well-established field of Asynchronous Byzantine Fault Tolerant (ABFT) systems. This allows us to formally reason about correctness, efficiency, and security in the strictest possible model, and thus convincingly prove the overall robustness of our solution. Our protocol improves upon the state-of-the-art HoneyBadgerBFT by Miller et al. by reducing the asymptotic latency while matching the optimal communication complexity. Furthermore, in contrast to the above, our protocol does not require a trusted dealer thanks to a novel implementation of a trustless ABFT Randomness Beacon.