The consensus protocol is a critical component of distributed ledgers and blockchains. Achieving consensus over a decentralized network poses challenges to transaction finality and performance. Currently, the highest-performing consensus algorithms are speculative BFT algorithms, which, however, compromise on the transaction finality guarantees offered by their non-speculative counterparts. In this paper, we introduce Albatross, a Proof-of-Stake (PoS) blockchain consensus algorithm that aims to combine the best of both worlds. At its heart, Albatross is a high-performing, speculative BFT algorithm that offers strong probabilistic finality. We complement this by periodically guaranteeing finality through the Tendermint protocol. We prove our protocol to be secure under standard BFT assumptions and analyze its performance both on a theoretical and practical level. For that, we provide an open-source Rust implementation of Albatross. Our real-world measurements support that our protocol has a performance close to the theoretical maximum for single-chain Proof-of-Stake consensus algorithms.

翻译：共识协议是分布式账本和区块链中的关键组成部分。在去中心化网络上达成共识对交易最终性和性能构成挑战。目前，性能最高的共识算法是推测性拜占庭容错（speculative BFT）算法，然而这类算法在交易最终性保障方面相比非推测性算法有所妥协。本文提出Albatross，这是一种权益证明（PoS）区块链共识算法，旨在融合两类算法的优势。其核心在于，Albatross是一种高性能的推测性BFT算法，提供强概率最终性，并通过定期运行Tendermint协议来确保最终性。我们证明该协议在标准BFT假设下是安全的，并从理论和实践层面分析其性能。为此，我们提供了Albatross的开源Rust实现。实际测量结果表明，该协议的性能接近单链权益证明共识算法的理论最大值。