Asynchronous Byzantine fault-tolerant (BFT) protocols assuming no timing assumptions are inherently more robust than their partially synchronous counterparts, but typically have much weaker security guarantees.We design new and efficient asynchronous BFT protocols matching all security guarantees of partially synchronous protocols. To achieve the goal, we have developed the local coin based BFT approach–one long deemed as being inefficient–and designed more efficient asynchronous binary agreement (ABA) protocols and their reproposable ABA (RABA) versions from local coins. Notably, our techniques on ABA and RABA allow us to build more efficient ABA protocols from common coins.We implemented four BFT protocols in a new Golang library, including BEAT, two WaterBear protocols, and FlatWorm. The WaterBear protocols use the conventional BFT workflow, while FlatWorm leverages the framework separating message transmission from consensus and significantly improves the system throughput.Via extensive evaluation, we show that our WaterBear protocols and FlatWorm are efficient under both failure-free and failure scenarios. Notably, WaterBear-QS consistently outperforms BEAT across all metrics and FlatWorm significantly outpaces WaterBear-QS. For example, with 16 replicas, FlatWorm achieves a throughput of 213.04ktx/sec—5.63× that of BEAT and 3.43× that of WaterBear-QS.

Most practical synchronous Byzantine fault-tolerant (BFT) protocols, such as Sync HotStuff (S&P 2020), follow the paradigm of partially synchronous BFT and adopt a deterministic design. While these protocols achieve$\mathbf{O}(\mathbf{n})$time complexity, they exhibit impressive performance in failure-free scenarios. This paper challenges this conventional wisdom, showing that a randomized paradigm terminating in expected$O(1)$time may well outperform prior ones even in the failure-free scenarios. Our framework reduces synchronous BFT to a new primitive called multi-valued Byzantine agreement with strong external validity (MBA-SEV). Inspired by the external validity property of multi-valued validated Byzantine agreement (MVBA), the additional validity properties allow us to build a BFT protocol where replicas agree on the hashes of the blocks. Our instantiation of the paradigm, Sonic, achieves$O(n)$amortized message complexity per block proposal, expected$O(1)$time, and enables a fast path of only two communication step. Our evaluation results using up to 91 instances on Amazon EC2 show that the peak throughput of Sonic and P-Sonic (a pipelining variant of Sonic) is$2.24 x-14.52 x$and$3.08 x-24.25 x$that of Sync HotStuff, respectively.

The stock market is a vital component of the financial sector. Due to the inherent uncertainty and volatility of the stock market, stock price prediction has always been both intriguing and challenging. To improve the accuracy of stock predictions, we construct a model that integrates investor sentiment with Long Short-Term Memory (LSTM) networks. By extracting sentiment data from the “Financial Post” and quantifying it with the Vader sentiment lexicon, we add a sentiment index to improve stock price forecasting. We combine sentiment factors with traditional trading indicators, making predictions more accurate. Furthermore, we deploy our system on the blockchain to enhance data security, reduce the risk of malicious attacks, and improve system robustness. This integration of sentiment analysis and blockchain offers a novel approach to stock market predictions, providing secure and reliable decision support for investors and financial institutions. We deploy our system and demonstrate that our system is both efficient and practical. For 312 bytes of stock data, we achieve a latency of 434.42 ms with one node and 565.69 ms with five nodes. For 1700 bytes of sentiment data, we achieve a latency of 1405.25 ms with one node and 1750.25 ms with five nodes.

State-of-the-art Byzantine fault-tolerant (BFT) protocols assuming partial synchrony such as SBFT and HotStuff use regular certificates obtained from 2f + 1 (partial) signatures. We show that one can use weak certificates obtained from only f + 1 signatures to assist in designing more robust and more efficient BFT protocols. We design and implement two BFT systems: Dashing (a family of two HotStuff-style BFT protocols) and Star (a parallel BFT framework).